26 files changed, 2591 insertions, 0 deletions

diff --git a/models/db/collation.go b/models/db/collation.go
new file mode 100644
index 0000000..39d28fa
--- /dev/null
+++ b/models/db/collation.go
@@ -0,0 +1,159 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"code.gitea.io/gitea/modules/container"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
+)
+
+type CheckCollationsResult struct {
+	ExpectedCollation        string
+	AvailableCollation       container.Set[string]
+	DatabaseCollation        string
+	IsCollationCaseSensitive func(s string) bool
+	CollationEquals          func(a, b string) bool
+	ExistingTableNumber      int
+
+	InconsistentCollationColumns []string
+}
+
+func findAvailableCollationsMySQL(x *xorm.Engine) (ret container.Set[string], err error) {
+	var res []struct {
+		Collation string
+	}
+	if err = x.SQL("SHOW COLLATION WHERE (Collation = 'utf8mb4_bin') OR (Collation LIKE '%\\_as\\_cs%')").Find(&res); err != nil {
+		return nil, err
+	}
+	ret = make(container.Set[string], len(res))
+	for _, r := range res {
+		ret.Add(r.Collation)
+	}
+	return ret, nil
+}
+
+func CheckCollations(x *xorm.Engine) (*CheckCollationsResult, error) {
+	dbTables, err := x.DBMetas()
+	if err != nil {
+		return nil, err
+	}
+
+	res := &CheckCollationsResult{
+		ExistingTableNumber: len(dbTables),
+		CollationEquals:     func(a, b string) bool { return a == b },
+	}
+
+	var candidateCollations []string
+	if x.Dialect().URI().DBType == schemas.MYSQL {
+		if _, err = x.SQL("SELECT @@collation_database").Get(&res.DatabaseCollation); err != nil {
+			return nil, err
+		}
+		res.IsCollationCaseSensitive = func(s string) bool {
+			return s == "utf8mb4_bin" || strings.HasSuffix(s, "_as_cs")
+		}
+		candidateCollations = []string{"utf8mb4_0900_as_cs", "uca1400_as_cs", "utf8mb4_bin"}
+		res.AvailableCollation, err = findAvailableCollationsMySQL(x)
+		if err != nil {
+			return nil, err
+		}
+		res.CollationEquals = func(a, b string) bool {
+			// MariaDB adds the "utf8mb4_" prefix, eg: "utf8mb4_uca1400_as_cs", but not the name "uca1400_as_cs" in "SHOW COLLATION"
+			// At the moment, it's safe to ignore the database difference, just trim the prefix and compare. It could be fixed easily if there is any problem in the future.
+			return a == b || strings.TrimPrefix(a, "utf8mb4_") == strings.TrimPrefix(b, "utf8mb4_")
+		}
+	} else {
+		return nil, nil
+	}
+
+	if res.DatabaseCollation == "" {
+		return nil, errors.New("unable to get collation for current database")
+	}
+
+	res.ExpectedCollation = setting.Database.CharsetCollation
+	if res.ExpectedCollation == "" {
+		for _, collation := range candidateCollations {
+			if res.AvailableCollation.Contains(collation) {
+				res.ExpectedCollation = collation
+				break
+			}
+		}
+	}
+
+	if res.ExpectedCollation == "" {
+		return nil, errors.New("unable to find a suitable collation for current database")
+	}
+
+	allColumnsMatchExpected := true
+	allColumnsMatchDatabase := true
+	for _, table := range dbTables {
+		for _, col := range table.Columns() {
+			if col.Collation != "" {
+				allColumnsMatchExpected = allColumnsMatchExpected && res.CollationEquals(col.Collation, res.ExpectedCollation)
+				allColumnsMatchDatabase = allColumnsMatchDatabase && res.CollationEquals(col.Collation, res.DatabaseCollation)
+				if !res.IsCollationCaseSensitive(col.Collation) || !res.CollationEquals(col.Collation, res.DatabaseCollation) {
+					res.InconsistentCollationColumns = append(res.InconsistentCollationColumns, fmt.Sprintf("%s.%s", table.Name, col.Name))
+				}
+			}
+		}
+	}
+	// if all columns match expected collation or all match database collation, then it could also be considered as "consistent"
+	if allColumnsMatchExpected || allColumnsMatchDatabase {
+		res.InconsistentCollationColumns = nil
+	}
+	return res, nil
+}
+
+func CheckCollationsDefaultEngine() (*CheckCollationsResult, error) {
+	return CheckCollations(x)
+}
+
+func alterDatabaseCollation(x *xorm.Engine, collation string) error {
+	if x.Dialect().URI().DBType == schemas.MYSQL {
+		_, err := x.Exec("ALTER DATABASE CHARACTER SET utf8mb4 COLLATE " + collation)
+		return err
+	}
+	return errors.New("unsupported database type")
+}
+
+// preprocessDatabaseCollation checks database & table column collation, and alter the database collation if needed
+func preprocessDatabaseCollation(x *xorm.Engine) {
+	r, err := CheckCollations(x)
+	if err != nil {
+		log.Error("Failed to check database collation: %v", err)
+	}
+	if r == nil {
+		return // no check result means the database doesn't need to do such check/process (at the moment ....)
+	}
+
+	// try to alter database collation to expected if the database is empty, it might fail in some cases (and it isn't necessary to succeed)
+	// at the moment.
+	if !r.CollationEquals(r.DatabaseCollation, r.ExpectedCollation) && r.ExistingTableNumber == 0 {
+		if err = alterDatabaseCollation(x, r.ExpectedCollation); err != nil {
+			log.Error("Failed to change database collation to %q: %v", r.ExpectedCollation, err)
+		} else {
+			if r, err = CheckCollations(x); err != nil {
+				log.Error("Failed to check database collation again after altering: %v", err) // impossible case
+				return
+			}
+			log.Warn("Current database has been altered to use collation %q", r.DatabaseCollation)
+		}
+	}
+
+	// check column collation, and show warning/error to end users -- no need to fatal, do not block the startup
+	if !r.IsCollationCaseSensitive(r.DatabaseCollation) {
+		log.Warn("Current database is using a case-insensitive collation %q, although Forgejo could work with it, there might be some rare cases which don't work as expected.", r.DatabaseCollation)
+	}
+
+	if len(r.InconsistentCollationColumns) > 0 {
+		log.Error("There are %d table columns using inconsistent collation, they should use %q. Please go to admin panel Self Check page", len(r.InconsistentCollationColumns), r.DatabaseCollation)
+	}
+}
diff --git a/models/db/common.go b/models/db/common.go
new file mode 100644
index 0000000..f3fd3e7
--- /dev/null
+++ b/models/db/common.go
@@ -0,0 +1,53 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"strings"
+
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
+
+	"xorm.io/builder"
+)
+
+// BuildCaseInsensitiveLike returns a condition to check if the given value is like the given key case-insensitively.
+// Handles especially SQLite correctly as UPPER there only transforms ASCII letters.
+func BuildCaseInsensitiveLike(key, value string) builder.Cond {
+	if setting.Database.Type.IsSQLite3() {
+		return builder.Like{"UPPER(" + key + ")", util.ToUpperASCII(value)}
+	}
+	return builder.Like{"UPPER(" + key + ")", strings.ToUpper(value)}
+}
+
+// BuildCaseInsensitiveIn returns a condition to check if the given value is in the given values case-insensitively.
+// Handles especially SQLite correctly as UPPER there only transforms ASCII letters.
+func BuildCaseInsensitiveIn(key string, values []string) builder.Cond {
+	uppers := make([]string, 0, len(values))
+	if setting.Database.Type.IsSQLite3() {
+		for _, value := range values {
+			uppers = append(uppers, util.ToUpperASCII(value))
+		}
+	} else {
+		for _, value := range values {
+			uppers = append(uppers, strings.ToUpper(value))
+		}
+	}
+
+	return builder.In("UPPER("+key+")", uppers)
+}
+
+// BuilderDialect returns the xorm.Builder dialect of the engine
+func BuilderDialect() string {
+	switch {
+	case setting.Database.Type.IsMySQL():
+		return builder.MYSQL
+	case setting.Database.Type.IsSQLite3():
+		return builder.SQLITE
+	case setting.Database.Type.IsPostgreSQL():
+		return builder.POSTGRES
+	default:
+		return ""
+	}
+}
diff --git a/models/db/consistency.go b/models/db/consistency.go
new file mode 100644
index 0000000..d19732c
--- /dev/null
+++ b/models/db/consistency.go
@@ -0,0 +1,31 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"context"
+
+	"xorm.io/builder"
+)
+
+// CountOrphanedObjects count subjects with have no existing refobject anymore
+func CountOrphanedObjects(ctx context.Context, subject, refobject, joinCond string) (int64, error) {
+	return GetEngine(ctx).
+		Table("`"+subject+"`").
+		Join("LEFT", "`"+refobject+"`", joinCond).
+		Where(builder.IsNull{"`" + refobject + "`.id"}).
+		Select("COUNT(`" + subject + "`.`id`)").
+		Count()
+}
+
+// DeleteOrphanedObjects delete subjects with have no existing refobject anymore
+func DeleteOrphanedObjects(ctx context.Context, subject, refobject, joinCond string) error {
+	subQuery := builder.Select("`"+subject+"`.id").
+		From("`"+subject+"`").
+		Join("LEFT", "`"+refobject+"`", joinCond).
+		Where(builder.IsNull{"`" + refobject + "`.id"})
+	b := builder.Delete(builder.In("id", subQuery)).From("`" + subject + "`")
+	_, err := GetEngine(ctx).Exec(b)
+	return err
+}
diff --git a/models/db/context.go b/models/db/context.go
new file mode 100644
index 0000000..43f6125
--- /dev/null
+++ b/models/db/context.go
@@ -0,0 +1,331 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"context"
+	"database/sql"
+
+	"xorm.io/builder"
+	"xorm.io/xorm"
+)
+
+// DefaultContext is the default context to run xorm queries in
+// will be overwritten by Init with HammerContext
+var DefaultContext context.Context
+
+// contextKey is a value for use with context.WithValue.
+type contextKey struct {
+	name string
+}
+
+// enginedContextKey is a context key. It is used with context.Value() to get the current Engined for the context
+var (
+	enginedContextKey         = &contextKey{"engined"}
+	_                 Engined = &Context{}
+)
+
+// Context represents a db context
+type Context struct {
+	context.Context
+	e           Engine
+	transaction bool
+}
+
+func newContext(ctx context.Context, e Engine, transaction bool) *Context {
+	return &Context{
+		Context:     ctx,
+		e:           e,
+		transaction: transaction,
+	}
+}
+
+// InTransaction if context is in a transaction
+func (ctx *Context) InTransaction() bool {
+	return ctx.transaction
+}
+
+// Engine returns db engine
+func (ctx *Context) Engine() Engine {
+	return ctx.e
+}
+
+// Value shadows Value for context.Context but allows us to get ourselves and an Engined object
+func (ctx *Context) Value(key any) any {
+	if key == enginedContextKey {
+		return ctx
+	}
+	return ctx.Context.Value(key)
+}
+
+// WithContext returns this engine tied to this context
+func (ctx *Context) WithContext(other context.Context) *Context {
+	return newContext(ctx, ctx.e.Context(other), ctx.transaction)
+}
+
+// Engined structs provide an Engine
+type Engined interface {
+	Engine() Engine
+}
+
+// GetEngine will get a db Engine from this context or return an Engine restricted to this context
+func GetEngine(ctx context.Context) Engine {
+	if e := getEngine(ctx); e != nil {
+		return e
+	}
+	return x.Context(ctx)
+}
+
+// getEngine will get a db Engine from this context or return nil
+func getEngine(ctx context.Context) Engine {
+	if engined, ok := ctx.(Engined); ok {
+		return engined.Engine()
+	}
+	enginedInterface := ctx.Value(enginedContextKey)
+	if enginedInterface != nil {
+		return enginedInterface.(Engined).Engine()
+	}
+	return nil
+}
+
+// Committer represents an interface to Commit or Close the Context
+type Committer interface {
+	Commit() error
+	Close() error
+}
+
+// halfCommitter is a wrapper of Committer.
+// It can be closed early, but can't be committed early, it is useful for reusing a transaction.
+type halfCommitter struct {
+	committer Committer
+	committed bool
+}
+
+func (c *halfCommitter) Commit() error {
+	c.committed = true
+	// should do nothing, and the parent committer will commit later
+	return nil
+}
+
+func (c *halfCommitter) Close() error {
+	if c.committed {
+		// it's "commit and close", should do nothing, and the parent committer will commit later
+		return nil
+	}
+
+	// it's "rollback and close", let the parent committer rollback right now
+	return c.committer.Close()
+}
+
+// TxContext represents a transaction Context,
+// it will reuse the existing transaction in the parent context or create a new one.
+// Some tips to use:
+//
+//	1 It's always recommended to use `WithTx` in new code instead of `TxContext`, since `WithTx` will handle the transaction automatically.
+//	2. To maintain the old code which uses `TxContext`:
+//	  a. Always call `Close()` before returning regardless of whether `Commit()` has been called.
+//	  b. Always call `Commit()` before returning if there are no errors, even if the code did not change any data.
+//	  c. Remember the `Committer` will be a halfCommitter when a transaction is being reused.
+//	     So calling `Commit()` will do nothing, but calling `Close()` without calling `Commit()` will rollback the transaction.
+//	     And all operations submitted by the caller stack will be rollbacked as well, not only the operations in the current function.
+//	  d. It doesn't mean rollback is forbidden, but always do it only when there is an error, and you do want to rollback.
+func TxContext(parentCtx context.Context) (*Context, Committer, error) {
+	if sess, ok := inTransaction(parentCtx); ok {
+		return newContext(parentCtx, sess, true), &halfCommitter{committer: sess}, nil
+	}
+
+	sess := x.NewSession()
+	if err := sess.Begin(); err != nil {
+		sess.Close()
+		return nil, nil, err
+	}
+
+	return newContext(DefaultContext, sess, true), sess, nil
+}
+
+// WithTx represents executing database operations on a transaction, if the transaction exist,
+// this function will reuse it otherwise will create a new one and close it when finished.
+func WithTx(parentCtx context.Context, f func(ctx context.Context) error) error {
+	if sess, ok := inTransaction(parentCtx); ok {
+		err := f(newContext(parentCtx, sess, true))
+		if err != nil {
+			// rollback immediately, in case the caller ignores returned error and tries to commit the transaction.
+			_ = sess.Close()
+		}
+		return err
+	}
+	return txWithNoCheck(parentCtx, f)
+}
+
+func txWithNoCheck(parentCtx context.Context, f func(ctx context.Context) error) error {
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	if err := f(newContext(parentCtx, sess, true)); err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}
+
+// Insert inserts records into database
+func Insert(ctx context.Context, beans ...any) error {
+	_, err := GetEngine(ctx).Insert(beans...)
+	return err
+}
+
+// Exec executes a sql with args
+func Exec(ctx context.Context, sqlAndArgs ...any) (sql.Result, error) {
+	return GetEngine(ctx).Exec(sqlAndArgs...)
+}
+
+func Get[T any](ctx context.Context, cond builder.Cond) (object *T, exist bool, err error) {
+	if !cond.IsValid() {
+		panic("cond is invalid in db.Get(ctx, cond). This should not be possible.")
+	}
+
+	var bean T
+	has, err := GetEngine(ctx).Where(cond).NoAutoCondition().Get(&bean)
+	if err != nil {
+		return nil, false, err
+	} else if !has {
+		return nil, false, nil
+	}
+	return &bean, true, nil
+}
+
+func GetByID[T any](ctx context.Context, id int64) (object *T, exist bool, err error) {
+	var bean T
+	has, err := GetEngine(ctx).ID(id).NoAutoCondition().Get(&bean)
+	if err != nil {
+		return nil, false, err
+	} else if !has {
+		return nil, false, nil
+	}
+	return &bean, true, nil
+}
+
+func Exist[T any](ctx context.Context, cond builder.Cond) (bool, error) {
+	if !cond.IsValid() {
+		panic("cond is invalid in db.Exist(ctx, cond). This should not be possible.")
+	}
+
+	var bean T
+	return GetEngine(ctx).Where(cond).NoAutoCondition().Exist(&bean)
+}
+
+func ExistByID[T any](ctx context.Context, id int64) (bool, error) {
+	var bean T
+	return GetEngine(ctx).ID(id).NoAutoCondition().Exist(&bean)
+}
+
+// DeleteByID deletes the given bean with the given ID
+func DeleteByID[T any](ctx context.Context, id int64) (int64, error) {
+	var bean T
+	return GetEngine(ctx).ID(id).NoAutoCondition().NoAutoTime().Delete(&bean)
+}
+
+func DeleteByIDs[T any](ctx context.Context, ids ...int64) error {
+	if len(ids) == 0 {
+		return nil
+	}
+
+	var bean T
+	_, err := GetEngine(ctx).In("id", ids).NoAutoCondition().NoAutoTime().Delete(&bean)
+	return err
+}
+
+func Delete[T any](ctx context.Context, opts FindOptions) (int64, error) {
+	if opts == nil || !opts.ToConds().IsValid() {
+		panic("opts are empty or invalid in db.Delete(ctx, opts). This should not be possible.")
+	}
+
+	var bean T
+	return GetEngine(ctx).Where(opts.ToConds()).NoAutoCondition().NoAutoTime().Delete(&bean)
+}
+
+// DeleteByBean deletes all records according non-empty fields of the bean as conditions.
+func DeleteByBean(ctx context.Context, bean any) (int64, error) {
+	return GetEngine(ctx).Delete(bean)
+}
+
+// FindIDs finds the IDs for the given table name satisfying the given condition
+// By passing a different value than "id" for "idCol", you can query for foreign IDs, i.e. the repo IDs which satisfy the condition
+func FindIDs(ctx context.Context, tableName, idCol string, cond builder.Cond) ([]int64, error) {
+	ids := make([]int64, 0, 10)
+	if err := GetEngine(ctx).Table(tableName).
+		Cols(idCol).
+		Where(cond).
+		Find(&ids); err != nil {
+		return nil, err
+	}
+	return ids, nil
+}
+
+// DecrByIDs decreases the given column for entities of the "bean" type with one of the given ids by one
+// Timestamps of the entities won't be updated
+func DecrByIDs(ctx context.Context, ids []int64, decrCol string, bean any) error {
+	_, err := GetEngine(ctx).Decr(decrCol).In("id", ids).NoAutoCondition().NoAutoTime().Update(bean)
+	return err
+}
+
+// DeleteBeans deletes all given beans, beans must contain delete conditions.
+func DeleteBeans(ctx context.Context, beans ...any) (err error) {
+	e := GetEngine(ctx)
+	for i := range beans {
+		if _, err = e.Delete(beans[i]); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// TruncateBeans deletes all given beans, beans may contain delete conditions.
+func TruncateBeans(ctx context.Context, beans ...any) (err error) {
+	e := GetEngine(ctx)
+	for i := range beans {
+		if _, err = e.Truncate(beans[i]); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// CountByBean counts the number of database records according non-empty fields of the bean as conditions.
+func CountByBean(ctx context.Context, bean any) (int64, error) {
+	return GetEngine(ctx).Count(bean)
+}
+
+// TableName returns the table name according a bean object
+func TableName(bean any) string {
+	return x.TableName(bean)
+}
+
+// InTransaction returns true if the engine is in a transaction otherwise return false
+func InTransaction(ctx context.Context) bool {
+	_, ok := inTransaction(ctx)
+	return ok
+}
+
+func inTransaction(ctx context.Context) (*xorm.Session, bool) {
+	e := getEngine(ctx)
+	if e == nil {
+		return nil, false
+	}
+
+	switch t := e.(type) {
+	case *xorm.Engine:
+		return nil, false
+	case *xorm.Session:
+		if t.IsInTx() {
+			return t, true
+		}
+		return nil, false
+	default:
+		return nil, false
+	}
+}
diff --git a/models/db/context_committer_test.go b/models/db/context_committer_test.go
new file mode 100644
index 0000000..38e91f2
--- /dev/null
+++ b/models/db/context_committer_test.go
@@ -0,0 +1,102 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db // it's not db_test, because this file is for testing the private type halfCommitter
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type MockCommitter struct {
+	wants []string
+	gots  []string
+}
+
+func NewMockCommitter(wants ...string) *MockCommitter {
+	return &MockCommitter{
+		wants: wants,
+	}
+}
+
+func (c *MockCommitter) Commit() error {
+	c.gots = append(c.gots, "commit")
+	return nil
+}
+
+func (c *MockCommitter) Close() error {
+	c.gots = append(c.gots, "close")
+	return nil
+}
+
+func (c *MockCommitter) Assert(t *testing.T) {
+	assert.Equal(t, c.wants, c.gots, "want operations %v, but got %v", c.wants, c.gots)
+}
+
+func Test_halfCommitter(t *testing.T) {
+	/*
+		Do something like:
+
+		ctx, committer, err := db.TxContext(db.DefaultContext)
+		if err != nil {
+			return nil
+		}
+		defer committer.Close()
+
+		// ...
+
+		if err != nil {
+			return nil
+		}
+
+		// ...
+
+		return committer.Commit()
+	*/
+
+	testWithCommitter := func(committer Committer, f func(committer Committer) error) {
+		if err := f(&halfCommitter{committer: committer}); err == nil {
+			committer.Commit()
+		}
+		committer.Close()
+	}
+
+	t.Run("commit and close", func(t *testing.T) {
+		mockCommitter := NewMockCommitter("commit", "close")
+
+		testWithCommitter(mockCommitter, func(committer Committer) error {
+			defer committer.Close()
+			return committer.Commit()
+		})
+
+		mockCommitter.Assert(t)
+	})
+
+	t.Run("rollback and close", func(t *testing.T) {
+		mockCommitter := NewMockCommitter("close", "close")
+
+		testWithCommitter(mockCommitter, func(committer Committer) error {
+			defer committer.Close()
+			if true {
+				return fmt.Errorf("error")
+			}
+			return committer.Commit()
+		})
+
+		mockCommitter.Assert(t)
+	})
+
+	t.Run("close and commit", func(t *testing.T) {
+		mockCommitter := NewMockCommitter("close", "close")
+
+		testWithCommitter(mockCommitter, func(committer Committer) error {
+			committer.Close()
+			committer.Commit()
+			return fmt.Errorf("error")
+		})
+
+		mockCommitter.Assert(t)
+	})
+}
diff --git a/models/db/context_test.go b/models/db/context_test.go
new file mode 100644
index 0000000..855f360
--- /dev/null
+++ b/models/db/context_test.go
@@ -0,0 +1,87 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db_test
+
+import (
+	"context"
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestInTransaction(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	assert.False(t, db.InTransaction(db.DefaultContext))
+	require.NoError(t, db.WithTx(db.DefaultContext, func(ctx context.Context) error {
+		assert.True(t, db.InTransaction(ctx))
+		return nil
+	}))
+
+	ctx, committer, err := db.TxContext(db.DefaultContext)
+	require.NoError(t, err)
+	defer committer.Close()
+	assert.True(t, db.InTransaction(ctx))
+	require.NoError(t, db.WithTx(ctx, func(ctx context.Context) error {
+		assert.True(t, db.InTransaction(ctx))
+		return nil
+	}))
+}
+
+func TestTxContext(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+
+	{ // create new transaction
+		ctx, committer, err := db.TxContext(db.DefaultContext)
+		require.NoError(t, err)
+		assert.True(t, db.InTransaction(ctx))
+		require.NoError(t, committer.Commit())
+	}
+
+	{ // reuse the transaction created by TxContext and commit it
+		ctx, committer, err := db.TxContext(db.DefaultContext)
+		engine := db.GetEngine(ctx)
+		require.NoError(t, err)
+		assert.True(t, db.InTransaction(ctx))
+		{
+			ctx, committer, err := db.TxContext(ctx)
+			require.NoError(t, err)
+			assert.True(t, db.InTransaction(ctx))
+			assert.Equal(t, engine, db.GetEngine(ctx))
+			require.NoError(t, committer.Commit())
+		}
+		require.NoError(t, committer.Commit())
+	}
+
+	{ // reuse the transaction created by TxContext and close it
+		ctx, committer, err := db.TxContext(db.DefaultContext)
+		engine := db.GetEngine(ctx)
+		require.NoError(t, err)
+		assert.True(t, db.InTransaction(ctx))
+		{
+			ctx, committer, err := db.TxContext(ctx)
+			require.NoError(t, err)
+			assert.True(t, db.InTransaction(ctx))
+			assert.Equal(t, engine, db.GetEngine(ctx))
+			require.NoError(t, committer.Close())
+		}
+		require.NoError(t, committer.Close())
+	}
+
+	{ // reuse the transaction created by WithTx
+		require.NoError(t, db.WithTx(db.DefaultContext, func(ctx context.Context) error {
+			assert.True(t, db.InTransaction(ctx))
+			{
+				ctx, committer, err := db.TxContext(ctx)
+				require.NoError(t, err)
+				assert.True(t, db.InTransaction(ctx))
+				require.NoError(t, committer.Commit())
+			}
+			return nil
+		}))
+	}
+}
diff --git a/models/db/convert.go b/models/db/convert.go
new file mode 100644
index 0000000..956e17d
--- /dev/null
+++ b/models/db/convert.go
@@ -0,0 +1,64 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
+)
+
+// ConvertDatabaseTable converts database and tables from utf8 to utf8mb4 if it's mysql and set ROW_FORMAT=dynamic
+func ConvertDatabaseTable() error {
+	if x.Dialect().URI().DBType != schemas.MYSQL {
+		return nil
+	}
+
+	r, err := CheckCollations(x)
+	if err != nil {
+		return err
+	}
+
+	databaseName := strings.SplitN(setting.Database.Name, "?", 2)[0]
+	_, err = x.Exec(fmt.Sprintf("ALTER DATABASE `%s` CHARACTER SET utf8mb4 COLLATE %s", databaseName, r.ExpectedCollation))
+	if err != nil {
+		return err
+	}
+
+	tables, err := x.DBMetas()
+	if err != nil {
+		return err
+	}
+	for _, table := range tables {
+		if _, err := x.Exec(fmt.Sprintf("ALTER TABLE `%s` ROW_FORMAT=dynamic", table.Name)); err != nil {
+			return err
+		}
+
+		if _, err := x.Exec(fmt.Sprintf("ALTER TABLE `%s` CONVERT TO CHARACTER SET utf8mb4 COLLATE %s", table.Name, r.ExpectedCollation)); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Cell2Int64 converts a xorm.Cell type to int64,
+// and handles possible irregular cases.
+func Cell2Int64(val xorm.Cell) int64 {
+	switch (*val).(type) {
+	case []uint8:
+		log.Trace("Cell2Int64 ([]uint8): %v", *val)
+
+		v, _ := strconv.ParseInt(string((*val).([]uint8)), 10, 64)
+		return v
+	default:
+		return (*val).(int64)
+	}
+}
diff --git a/models/db/engine.go b/models/db/engine.go
new file mode 100755
index 0000000..6164959
--- /dev/null
+++ b/models/db/engine.go
@@ -0,0 +1,354 @@
+// Copyright 2014 The Gogs Authors. All rights reserved.
+// Copyright 2018 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	"io"
+	"reflect"
+	"strings"
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/xorm"
+	"xorm.io/xorm/contexts"
+	"xorm.io/xorm/names"
+	"xorm.io/xorm/schemas"
+
+	_ "github.com/go-sql-driver/mysql" // Needed for the MySQL driver
+	_ "github.com/lib/pq"              // Needed for the Postgresql driver
+)
+
+var (
+	x         *xorm.Engine
+	tables    []any
+	initFuncs []func() error
+)
+
+// Engine represents a xorm engine or session.
+type Engine interface {
+	Table(tableNameOrBean any) *xorm.Session
+	Count(...any) (int64, error)
+	Decr(column string, arg ...any) *xorm.Session
+	Delete(...any) (int64, error)
+	Truncate(...any) (int64, error)
+	Exec(...any) (sql.Result, error)
+	Find(any, ...any) error
+	Get(beans ...any) (bool, error)
+	ID(any) *xorm.Session
+	In(string, ...any) *xorm.Session
+	Incr(column string, arg ...any) *xorm.Session
+	Insert(...any) (int64, error)
+	Iterate(any, xorm.IterFunc) error
+	IsTableExist(any) (bool, error)
+	Join(joinOperator string, tablename, condition any, args ...any) *xorm.Session
+	SQL(any, ...any) *xorm.Session
+	Where(any, ...any) *xorm.Session
+	Asc(colNames ...string) *xorm.Session
+	Desc(colNames ...string) *xorm.Session
+	Limit(limit int, start ...int) *xorm.Session
+	NoAutoTime() *xorm.Session
+	SumInt(bean any, columnName string) (res int64, err error)
+	Sync(...any) error
+	Select(string) *xorm.Session
+	SetExpr(string, any) *xorm.Session
+	NotIn(string, ...any) *xorm.Session
+	OrderBy(any, ...any) *xorm.Session
+	Exist(...any) (bool, error)
+	Distinct(...string) *xorm.Session
+	Query(...any) ([]map[string][]byte, error)
+	Cols(...string) *xorm.Session
+	Context(ctx context.Context) *xorm.Session
+	Ping() error
+}
+
+// TableInfo returns table's information via an object
+func TableInfo(v any) (*schemas.Table, error) {
+	return x.TableInfo(v)
+}
+
+// DumpTables dump tables information
+func DumpTables(tables []*schemas.Table, w io.Writer, tp ...schemas.DBType) error {
+	return x.DumpTables(tables, w, tp...)
+}
+
+// RegisterModel registers model, if initfunc provided, it will be invoked after data model sync
+func RegisterModel(bean any, initFunc ...func() error) {
+	tables = append(tables, bean)
+	if len(initFuncs) > 0 && initFunc[0] != nil {
+		initFuncs = append(initFuncs, initFunc[0])
+	}
+}
+
+func init() {
+	gonicNames := []string{"SSL", "UID"}
+	for _, name := range gonicNames {
+		names.LintGonicMapper[name] = true
+	}
+}
+
+// newXORMEngine returns a new XORM engine from the configuration
+func newXORMEngine() (*xorm.Engine, error) {
+	connStr, err := setting.DBConnStr()
+	if err != nil {
+		return nil, err
+	}
+
+	var engine *xorm.Engine
+
+	if setting.Database.Type.IsPostgreSQL() && len(setting.Database.Schema) > 0 {
+		// OK whilst we sort out our schema issues - create a schema aware postgres
+		registerPostgresSchemaDriver()
+		engine, err = xorm.NewEngine("postgresschema", connStr)
+	} else {
+		engine, err = xorm.NewEngine(setting.Database.Type.String(), connStr)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+	if setting.Database.Type.IsMySQL() {
+		engine.Dialect().SetParams(map[string]string{"rowFormat": "DYNAMIC"})
+	}
+	engine.SetSchema(setting.Database.Schema)
+	return engine, nil
+}
+
+// SyncAllTables sync the schemas of all tables, is required by unit test code
+func SyncAllTables() error {
+	_, err := x.StoreEngine("InnoDB").SyncWithOptions(xorm.SyncOptions{
+		WarnIfDatabaseColumnMissed: true,
+	}, tables...)
+	return err
+}
+
+// InitEngine initializes the xorm.Engine and sets it as db.DefaultContext
+func InitEngine(ctx context.Context) error {
+	xormEngine, err := newXORMEngine()
+	if err != nil {
+		return fmt.Errorf("failed to connect to database: %w", err)
+	}
+
+	xormEngine.SetMapper(names.GonicMapper{})
+	// WARNING: for serv command, MUST remove the output to os.stdout,
+	// so use log file to instead print to stdout.
+	xormEngine.SetLogger(NewXORMLogger(setting.Database.LogSQL))
+	xormEngine.ShowSQL(setting.Database.LogSQL)
+	xormEngine.SetMaxOpenConns(setting.Database.MaxOpenConns)
+	xormEngine.SetMaxIdleConns(setting.Database.MaxIdleConns)
+	xormEngine.SetConnMaxLifetime(setting.Database.ConnMaxLifetime)
+	xormEngine.SetConnMaxIdleTime(setting.Database.ConnMaxIdleTime)
+	xormEngine.SetDefaultContext(ctx)
+
+	if setting.Database.SlowQueryThreshold > 0 {
+		xormEngine.AddHook(&SlowQueryHook{
+			Treshold: setting.Database.SlowQueryThreshold,
+			Logger:   log.GetLogger("xorm"),
+		})
+	}
+
+	errorLogger := log.GetLogger("xorm")
+	if setting.IsInTesting {
+		errorLogger = log.GetLogger(log.DEFAULT)
+	}
+
+	xormEngine.AddHook(&ErrorQueryHook{
+		Logger: errorLogger,
+	})
+
+	SetDefaultEngine(ctx, xormEngine)
+	return nil
+}
+
+// SetDefaultEngine sets the default engine for db
+func SetDefaultEngine(ctx context.Context, eng *xorm.Engine) {
+	x = eng
+	DefaultContext = &Context{
+		Context: ctx,
+		e:       x,
+	}
+}
+
+// UnsetDefaultEngine closes and unsets the default engine
+// We hope the SetDefaultEngine and UnsetDefaultEngine can be paired, but it's impossible now,
+// there are many calls to InitEngine -> SetDefaultEngine directly to overwrite the `x` and DefaultContext without close
+// Global database engine related functions are all racy and there is no graceful close right now.
+func UnsetDefaultEngine() {
+	if x != nil {
+		_ = x.Close()
+		x = nil
+	}
+	DefaultContext = nil
+}
+
+// InitEngineWithMigration initializes a new xorm.Engine and sets it as the db.DefaultContext
+// This function must never call .Sync() if the provided migration function fails.
+// When called from the "doctor" command, the migration function is a version check
+// that prevents the doctor from fixing anything in the database if the migration level
+// is different from the expected value.
+func InitEngineWithMigration(ctx context.Context, migrateFunc func(*xorm.Engine) error) (err error) {
+	if err = InitEngine(ctx); err != nil {
+		return err
+	}
+
+	if err = x.Ping(); err != nil {
+		return err
+	}
+
+	preprocessDatabaseCollation(x)
+
+	// We have to run migrateFunc here in case the user is re-running installation on a previously created DB.
+	// If we do not then table schemas will be changed and there will be conflicts when the migrations run properly.
+	//
+	// Installation should only be being re-run if users want to recover an old database.
+	// However, we should think carefully about should we support re-install on an installed instance,
+	// as there may be other problems due to secret reinitialization.
+	if err = migrateFunc(x); err != nil {
+		return fmt.Errorf("migrate: %w", err)
+	}
+
+	if err = SyncAllTables(); err != nil {
+		return fmt.Errorf("sync database struct error: %w", err)
+	}
+
+	for _, initFunc := range initFuncs {
+		if err := initFunc(); err != nil {
+			return fmt.Errorf("initFunc failed: %w", err)
+		}
+	}
+
+	return nil
+}
+
+// NamesToBean return a list of beans or an error
+func NamesToBean(names ...string) ([]any, error) {
+	beans := []any{}
+	if len(names) == 0 {
+		beans = append(beans, tables...)
+		return beans, nil
+	}
+	// Need to map provided names to beans...
+	beanMap := make(map[string]any)
+	for _, bean := range tables {
+		beanMap[strings.ToLower(reflect.Indirect(reflect.ValueOf(bean)).Type().Name())] = bean
+		beanMap[strings.ToLower(x.TableName(bean))] = bean
+		beanMap[strings.ToLower(x.TableName(bean, true))] = bean
+	}
+
+	gotBean := make(map[any]bool)
+	for _, name := range names {
+		bean, ok := beanMap[strings.ToLower(strings.TrimSpace(name))]
+		if !ok {
+			return nil, fmt.Errorf("no table found that matches: %s", name)
+		}
+		if !gotBean[bean] {
+			beans = append(beans, bean)
+			gotBean[bean] = true
+		}
+	}
+	return beans, nil
+}
+
+// DumpDatabase dumps all data from database according the special database SQL syntax to file system.
+func DumpDatabase(filePath, dbType string) error {
+	var tbs []*schemas.Table
+	for _, t := range tables {
+		t, err := x.TableInfo(t)
+		if err != nil {
+			return err
+		}
+		tbs = append(tbs, t)
+	}
+
+	type Version struct {
+		ID      int64 `xorm:"pk autoincr"`
+		Version int64
+	}
+	t, err := x.TableInfo(&Version{})
+	if err != nil {
+		return err
+	}
+	tbs = append(tbs, t)
+
+	if len(dbType) > 0 {
+		return x.DumpTablesToFile(tbs, filePath, schemas.DBType(dbType))
+	}
+	return x.DumpTablesToFile(tbs, filePath)
+}
+
+// MaxBatchInsertSize returns the table's max batch insert size
+func MaxBatchInsertSize(bean any) int {
+	t, err := x.TableInfo(bean)
+	if err != nil {
+		return 50
+	}
+	return 999 / len(t.ColumnsSeq())
+}
+
+// IsTableNotEmpty returns true if table has at least one record
+func IsTableNotEmpty(beanOrTableName any) (bool, error) {
+	return x.Table(beanOrTableName).Exist()
+}
+
+// DeleteAllRecords will delete all the records of this table
+func DeleteAllRecords(tableName string) error {
+	_, err := x.Exec(fmt.Sprintf("DELETE FROM %s", tableName))
+	return err
+}
+
+// GetMaxID will return max id of the table
+func GetMaxID(beanOrTableName any) (maxID int64, err error) {
+	_, err = x.Select("MAX(id)").Table(beanOrTableName).Get(&maxID)
+	return maxID, err
+}
+
+func SetLogSQL(ctx context.Context, on bool) {
+	e := GetEngine(ctx)
+	if x, ok := e.(*xorm.Engine); ok {
+		x.ShowSQL(on)
+	} else if sess, ok := e.(*xorm.Session); ok {
+		sess.Engine().ShowSQL(on)
+	}
+}
+
+type SlowQueryHook struct {
+	Treshold time.Duration
+	Logger   log.Logger
+}
+
+var _ contexts.Hook = &SlowQueryHook{}
+
+func (SlowQueryHook) BeforeProcess(c *contexts.ContextHook) (context.Context, error) {
+	return c.Ctx, nil
+}
+
+func (h *SlowQueryHook) AfterProcess(c *contexts.ContextHook) error {
+	if c.ExecuteTime >= h.Treshold {
+		h.Logger.Log(8, log.WARN, "[Slow SQL Query] %s %v - %v", c.SQL, c.Args, c.ExecuteTime)
+	}
+	return nil
+}
+
+type ErrorQueryHook struct {
+	Logger log.Logger
+}
+
+var _ contexts.Hook = &ErrorQueryHook{}
+
+func (ErrorQueryHook) BeforeProcess(c *contexts.ContextHook) (context.Context, error) {
+	return c.Ctx, nil
+}
+
+func (h *ErrorQueryHook) AfterProcess(c *contexts.ContextHook) error {
+	if c.Err != nil && !errors.Is(c.Err, context.Canceled) {
+		h.Logger.Log(8, log.ERROR, "[Error SQL Query] %s %v - %v", c.SQL, c.Args, c.Err)
+	}
+	return nil
+}
diff --git a/models/db/engine_test.go b/models/db/engine_test.go
new file mode 100644
index 0000000..230ee3f
--- /dev/null
+++ b/models/db/engine_test.go
@@ -0,0 +1,154 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db_test
+
+import (
+	"path/filepath"
+	"testing"
+	"time"
+
+	"code.gitea.io/gitea/models/db"
+	issues_model "code.gitea.io/gitea/models/issues"
+	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
+
+	_ "code.gitea.io/gitea/cmd" // for TestPrimaryKeys
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"xorm.io/xorm"
+)
+
+func TestDumpDatabase(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+
+	dir := t.TempDir()
+
+	type Version struct {
+		ID      int64 `xorm:"pk autoincr"`
+		Version int64
+	}
+	require.NoError(t, db.GetEngine(db.DefaultContext).Sync(new(Version)))
+
+	for _, dbType := range setting.SupportedDatabaseTypes {
+		require.NoError(t, db.DumpDatabase(filepath.Join(dir, dbType+".sql"), dbType))
+	}
+}
+
+func TestDeleteOrphanedObjects(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+
+	countBefore, err := db.GetEngine(db.DefaultContext).Count(&issues_model.PullRequest{})
+	require.NoError(t, err)
+
+	_, err = db.GetEngine(db.DefaultContext).Insert(&issues_model.PullRequest{IssueID: 1000}, &issues_model.PullRequest{IssueID: 1001}, &issues_model.PullRequest{IssueID: 1003})
+	require.NoError(t, err)
+
+	orphaned, err := db.CountOrphanedObjects(db.DefaultContext, "pull_request", "issue", "pull_request.issue_id=issue.id")
+	require.NoError(t, err)
+	assert.EqualValues(t, 3, orphaned)
+
+	err = db.DeleteOrphanedObjects(db.DefaultContext, "pull_request", "issue", "pull_request.issue_id=issue.id")
+	require.NoError(t, err)
+
+	countAfter, err := db.GetEngine(db.DefaultContext).Count(&issues_model.PullRequest{})
+	require.NoError(t, err)
+	assert.EqualValues(t, countBefore, countAfter)
+}
+
+func TestPrimaryKeys(t *testing.T) {
+	// Some dbs require that all tables have primary keys, see
+	//   https://github.com/go-gitea/gitea/issues/21086
+	//   https://github.com/go-gitea/gitea/issues/16802
+	// To avoid creating tables without primary key again, this test will check them.
+	// Import "code.gitea.io/gitea/cmd" to make sure each db.RegisterModel in init functions has been called.
+
+	beans, err := db.NamesToBean()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	whitelist := map[string]string{
+		"the_table_name_to_skip_checking": "Write a note here to explain why",
+		"forgejo_sem_ver":                 "seriously dude",
+	}
+
+	for _, bean := range beans {
+		table, err := db.TableInfo(bean)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if why, ok := whitelist[table.Name]; ok {
+			t.Logf("ignore %q because %q", table.Name, why)
+			continue
+		}
+		if len(table.PrimaryKeys) == 0 {
+			t.Errorf("table %q has no primary key", table.Name)
+		}
+	}
+}
+
+func TestSlowQuery(t *testing.T) {
+	lc, cleanup := test.NewLogChecker("slow-query", log.INFO)
+	lc.StopMark("[Slow SQL Query]")
+	defer cleanup()
+
+	e := db.GetEngine(db.DefaultContext)
+	engine, ok := e.(*xorm.Engine)
+	assert.True(t, ok)
+
+	// It's not possible to clean this up with XORM, but it's luckily not harmful
+	// to leave around.
+	engine.AddHook(&db.SlowQueryHook{
+		Treshold: time.Second * 10,
+		Logger:   log.GetLogger("slow-query"),
+	})
+
+	// NOOP query.
+	e.Exec("SELECT 1 WHERE false;")
+
+	_, stopped := lc.Check(100 * time.Millisecond)
+	assert.False(t, stopped)
+
+	engine.AddHook(&db.SlowQueryHook{
+		Treshold: 0, // Every query should be logged.
+		Logger:   log.GetLogger("slow-query"),
+	})
+
+	// NOOP query.
+	e.Exec("SELECT 1 WHERE false;")
+
+	_, stopped = lc.Check(100 * time.Millisecond)
+	assert.True(t, stopped)
+}
+
+func TestErrorQuery(t *testing.T) {
+	lc, cleanup := test.NewLogChecker("error-query", log.INFO)
+	lc.StopMark("[Error SQL Query]")
+	defer cleanup()
+
+	e := db.GetEngine(db.DefaultContext)
+	engine, ok := e.(*xorm.Engine)
+	assert.True(t, ok)
+
+	// It's not possible to clean this up with XORM, but it's luckily not harmful
+	// to leave around.
+	engine.AddHook(&db.ErrorQueryHook{
+		Logger: log.GetLogger("error-query"),
+	})
+
+	// Valid query.
+	e.Exec("SELECT 1 WHERE false;")
+
+	_, stopped := lc.Check(100 * time.Millisecond)
+	assert.False(t, stopped)
+
+	// Table doesn't exist.
+	e.Exec("SELECT column FROM table;")
+
+	_, stopped = lc.Check(100 * time.Millisecond)
+	assert.True(t, stopped)
+}
diff --git a/models/db/error.go b/models/db/error.go
new file mode 100644
index 0000000..665e970
--- /dev/null
+++ b/models/db/error.go
@@ -0,0 +1,74 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"fmt"
+
+	"code.gitea.io/gitea/modules/util"
+)
+
+// ErrCancelled represents an error due to context cancellation
+type ErrCancelled struct {
+	Message string
+}
+
+// IsErrCancelled checks if an error is a ErrCancelled.
+func IsErrCancelled(err error) bool {
+	_, ok := err.(ErrCancelled)
+	return ok
+}
+
+func (err ErrCancelled) Error() string {
+	return "Cancelled: " + err.Message
+}
+
+// ErrCancelledf returns an ErrCancelled for the provided format and args
+func ErrCancelledf(format string, args ...any) error {
+	return ErrCancelled{
+		fmt.Sprintf(format, args...),
+	}
+}
+
+// ErrSSHDisabled represents an "SSH disabled" error.
+type ErrSSHDisabled struct{}
+
+// IsErrSSHDisabled checks if an error is a ErrSSHDisabled.
+func IsErrSSHDisabled(err error) bool {
+	_, ok := err.(ErrSSHDisabled)
+	return ok
+}
+
+func (err ErrSSHDisabled) Error() string {
+	return "SSH is disabled"
+}
+
+// ErrNotExist represents a non-exist error.
+type ErrNotExist struct {
+	Resource string
+	ID       int64
+}
+
+// IsErrNotExist checks if an error is an ErrNotExist
+func IsErrNotExist(err error) bool {
+	_, ok := err.(ErrNotExist)
+	return ok
+}
+
+func (err ErrNotExist) Error() string {
+	name := "record"
+	if err.Resource != "" {
+		name = err.Resource
+	}
+
+	if err.ID != 0 {
+		return fmt.Sprintf("%s does not exist [id: %d]", name, err.ID)
+	}
+	return fmt.Sprintf("%s does not exist", name)
+}
+
+// Unwrap unwraps this as a ErrNotExist err
+func (err ErrNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
diff --git a/models/db/index.go b/models/db/index.go
new file mode 100644
index 0000000..259ddd6
--- /dev/null
+++ b/models/db/index.go
@@ -0,0 +1,148 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strconv"
+
+	"code.gitea.io/gitea/modules/setting"
+)
+
+// ResourceIndex represents a resource index which could be used as issue/release and others
+// We can create different tables i.e. issue_index, release_index, etc.
+type ResourceIndex struct {
+	GroupID  int64 `xorm:"pk"`
+	MaxIndex int64 `xorm:"index"`
+}
+
+var (
+	// ErrResouceOutdated represents an error when request resource outdated
+	ErrResouceOutdated = errors.New("resource outdated")
+	// ErrGetResourceIndexFailed represents an error when resource index retries 3 times
+	ErrGetResourceIndexFailed = errors.New("get resource index failed")
+)
+
+// SyncMaxResourceIndex sync the max index with the resource
+func SyncMaxResourceIndex(ctx context.Context, tableName string, groupID, maxIndex int64) (err error) {
+	e := GetEngine(ctx)
+
+	// try to update the max_index and acquire the write-lock for the record
+	res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=? WHERE group_id=? AND max_index<?", tableName), maxIndex, groupID, maxIndex)
+	if err != nil {
+		return err
+	}
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return err
+	}
+	if affected == 0 {
+		// if nothing is updated, the record might not exist or might be larger, it's safe to try to insert it again and then check whether the record exists
+		_, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, ?)", tableName), groupID, maxIndex)
+		var savedIdx int64
+		has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&savedIdx)
+		if err != nil {
+			return err
+		}
+		// if the record still doesn't exist, there must be some errors (insert error)
+		if !has {
+			if errIns == nil {
+				return errors.New("impossible error when SyncMaxResourceIndex, insert succeeded but no record is saved")
+			}
+			return errIns
+		}
+	}
+	return nil
+}
+
+func postgresGetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
+	res, err := GetEngine(ctx).Query(fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
+		"VALUES (?,1) ON CONFLICT (group_id) DO UPDATE SET max_index = %s.max_index+1 RETURNING max_index",
+		tableName, tableName), groupID)
+	if err != nil {
+		return 0, err
+	}
+	if len(res) == 0 {
+		return 0, ErrGetResourceIndexFailed
+	}
+	return strconv.ParseInt(string(res[0]["max_index"]), 10, 64)
+}
+
+func mysqlGetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
+	if _, err := GetEngine(ctx).Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
+		"VALUES (?,1) ON DUPLICATE KEY UPDATE max_index = max_index+1",
+		tableName), groupID); err != nil {
+		return 0, err
+	}
+
+	var idx int64
+	_, err := GetEngine(ctx).SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ?", tableName), groupID).Get(&idx)
+	if err != nil {
+		return 0, err
+	}
+	if idx == 0 {
+		return 0, errors.New("cannot get the correct index")
+	}
+	return idx, nil
+}
+
+// GetNextResourceIndex generates a resource index, it must run in the same transaction where the resource is created
+func GetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
+	switch {
+	case setting.Database.Type.IsPostgreSQL():
+		return postgresGetNextResourceIndex(ctx, tableName, groupID)
+	case setting.Database.Type.IsMySQL():
+		return mysqlGetNextResourceIndex(ctx, tableName, groupID)
+	}
+
+	e := GetEngine(ctx)
+
+	// try to update the max_index to next value, and acquire the write-lock for the record
+	res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
+	if err != nil {
+		return 0, err
+	}
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return 0, err
+	}
+	if affected == 0 {
+		// this slow path is only for the first time of creating a resource index
+		_, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, 0)", tableName), groupID)
+		res, err = e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
+		if err != nil {
+			return 0, err
+		}
+		affected, err = res.RowsAffected()
+		if err != nil {
+			return 0, err
+		}
+		// if the update still can not update any records, the record must not exist and there must be some errors (insert error)
+		if affected == 0 {
+			if errIns == nil {
+				return 0, errors.New("impossible error when GetNextResourceIndex, insert and update both succeeded but no record is updated")
+			}
+			return 0, errIns
+		}
+	}
+
+	// now, the new index is in database (protected by the transaction and write-lock)
+	var newIdx int64
+	has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&newIdx)
+	if err != nil {
+		return 0, err
+	}
+	if !has {
+		return 0, errors.New("impossible error when GetNextResourceIndex, upsert succeeded but no record can be selected")
+	}
+	return newIdx, nil
+}
+
+// DeleteResourceIndex delete resource index
+func DeleteResourceIndex(ctx context.Context, tableName string, groupID int64) error {
+	_, err := Exec(ctx, fmt.Sprintf("DELETE FROM %s WHERE group_id=?", tableName), groupID)
+	return err
+}
diff --git a/models/db/index_test.go b/models/db/index_test.go
new file mode 100644
index 0000000..11fbc70
--- /dev/null
+++ b/models/db/index_test.go
@@ -0,0 +1,127 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db_test
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type TestIndex db.ResourceIndex
+
+func getCurrentResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
+	e := db.GetEngine(ctx)
+	var idx int64
+	has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&idx)
+	if err != nil {
+		return 0, err
+	}
+	if !has {
+		return 0, errors.New("no record")
+	}
+	return idx, nil
+}
+
+func TestSyncMaxResourceIndex(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	xe := unittest.GetXORMEngine()
+	require.NoError(t, xe.Sync(&TestIndex{}))
+
+	err := db.SyncMaxResourceIndex(db.DefaultContext, "test_index", 10, 51)
+	require.NoError(t, err)
+
+	// sync new max index
+	maxIndex, err := getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
+	require.NoError(t, err)
+	assert.EqualValues(t, 51, maxIndex)
+
+	// smaller index doesn't change
+	err = db.SyncMaxResourceIndex(db.DefaultContext, "test_index", 10, 30)
+	require.NoError(t, err)
+	maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
+	require.NoError(t, err)
+	assert.EqualValues(t, 51, maxIndex)
+
+	// larger index changes
+	err = db.SyncMaxResourceIndex(db.DefaultContext, "test_index", 10, 62)
+	require.NoError(t, err)
+	maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
+	require.NoError(t, err)
+	assert.EqualValues(t, 62, maxIndex)
+
+	// commit transaction
+	err = db.WithTx(db.DefaultContext, func(ctx context.Context) error {
+		err = db.SyncMaxResourceIndex(ctx, "test_index", 10, 73)
+		require.NoError(t, err)
+		maxIndex, err = getCurrentResourceIndex(ctx, "test_index", 10)
+		require.NoError(t, err)
+		assert.EqualValues(t, 73, maxIndex)
+		return nil
+	})
+	require.NoError(t, err)
+	maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
+	require.NoError(t, err)
+	assert.EqualValues(t, 73, maxIndex)
+
+	// rollback transaction
+	err = db.WithTx(db.DefaultContext, func(ctx context.Context) error {
+		err = db.SyncMaxResourceIndex(ctx, "test_index", 10, 84)
+		maxIndex, err = getCurrentResourceIndex(ctx, "test_index", 10)
+		require.NoError(t, err)
+		assert.EqualValues(t, 84, maxIndex)
+		return errors.New("test rollback")
+	})
+	require.Error(t, err)
+	maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
+	require.NoError(t, err)
+	assert.EqualValues(t, 73, maxIndex) // the max index doesn't change because the transaction was rolled back
+}
+
+func TestGetNextResourceIndex(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	xe := unittest.GetXORMEngine()
+	require.NoError(t, xe.Sync(&TestIndex{}))
+
+	// create a new record
+	maxIndex, err := db.GetNextResourceIndex(db.DefaultContext, "test_index", 20)
+	require.NoError(t, err)
+	assert.EqualValues(t, 1, maxIndex)
+
+	// increase the existing record
+	maxIndex, err = db.GetNextResourceIndex(db.DefaultContext, "test_index", 20)
+	require.NoError(t, err)
+	assert.EqualValues(t, 2, maxIndex)
+
+	// commit transaction
+	err = db.WithTx(db.DefaultContext, func(ctx context.Context) error {
+		maxIndex, err = db.GetNextResourceIndex(ctx, "test_index", 20)
+		require.NoError(t, err)
+		assert.EqualValues(t, 3, maxIndex)
+		return nil
+	})
+	require.NoError(t, err)
+	maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 20)
+	require.NoError(t, err)
+	assert.EqualValues(t, 3, maxIndex)
+
+	// rollback transaction
+	err = db.WithTx(db.DefaultContext, func(ctx context.Context) error {
+		maxIndex, err = db.GetNextResourceIndex(ctx, "test_index", 20)
+		require.NoError(t, err)
+		assert.EqualValues(t, 4, maxIndex)
+		return errors.New("test rollback")
+	})
+	require.Error(t, err)
+	maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 20)
+	require.NoError(t, err)
+	assert.EqualValues(t, 3, maxIndex) // the max index doesn't change because the transaction was rolled back
+}
diff --git a/models/db/install/db.go b/models/db/install/db.go
new file mode 100644
index 0000000..d4c1139
--- /dev/null
+++ b/models/db/install/db.go
@@ -0,0 +1,64 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package install
+
+import (
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/xorm"
+)
+
+func getXORMEngine() *xorm.Engine {
+	return db.DefaultContext.(*db.Context).Engine().(*xorm.Engine)
+}
+
+// CheckDatabaseConnection checks the database connection
+func CheckDatabaseConnection() error {
+	e := db.GetEngine(db.DefaultContext)
+	_, err := e.Exec("SELECT 1")
+	return err
+}
+
+// GetMigrationVersion gets the database migration version
+func GetMigrationVersion() (int64, error) {
+	var installedDbVersion int64
+	x := getXORMEngine()
+	exist, err := x.IsTableExist("version")
+	if err != nil {
+		return 0, err
+	}
+	if !exist {
+		return 0, nil
+	}
+	_, err = x.Table("version").Cols("version").Get(&installedDbVersion)
+	if err != nil {
+		return 0, err
+	}
+	return installedDbVersion, nil
+}
+
+// HasPostInstallationUsers checks whether there are users after installation
+func HasPostInstallationUsers() (bool, error) {
+	x := getXORMEngine()
+	exist, err := x.IsTableExist("user")
+	if err != nil {
+		return false, err
+	}
+	if !exist {
+		return false, nil
+	}
+
+	// if there are 2 or more users in database, we consider there are users created after installation
+	threshold := 2
+	if !setting.IsProd {
+		// to debug easily, with non-prod RUN_MODE, we only check the count to 1
+		threshold = 1
+	}
+	res, err := x.Table("user").Cols("id").Limit(threshold).Query()
+	if err != nil {
+		return false, err
+	}
+	return len(res) >= threshold, nil
+}
diff --git a/models/db/iterate.go b/models/db/iterate.go
new file mode 100644
index 0000000..e1caefa
--- /dev/null
+++ b/models/db/iterate.go
@@ -0,0 +1,43 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/builder"
+)
+
+// Iterate iterate all the Bean object
+func Iterate[Bean any](ctx context.Context, cond builder.Cond, f func(ctx context.Context, bean *Bean) error) error {
+	var start int
+	batchSize := setting.Database.IterateBufferSize
+	sess := GetEngine(ctx)
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+			beans := make([]*Bean, 0, batchSize)
+			if cond != nil {
+				sess = sess.Where(cond)
+			}
+			if err := sess.Limit(batchSize, start).Find(&beans); err != nil {
+				return err
+			}
+			if len(beans) == 0 {
+				return nil
+			}
+			start += len(beans)
+
+			for _, bean := range beans {
+				if err := f(ctx, bean); err != nil {
+					return err
+				}
+			}
+		}
+	}
+}
diff --git a/models/db/iterate_test.go b/models/db/iterate_test.go
new file mode 100644
index 0000000..7535d01
--- /dev/null
+++ b/models/db/iterate_test.go
@@ -0,0 +1,45 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db_test
+
+import (
+	"context"
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIterate(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	xe := unittest.GetXORMEngine()
+	require.NoError(t, xe.Sync(&repo_model.RepoUnit{}))
+
+	cnt, err := db.GetEngine(db.DefaultContext).Count(&repo_model.RepoUnit{})
+	require.NoError(t, err)
+
+	var repoUnitCnt int
+	err = db.Iterate(db.DefaultContext, nil, func(ctx context.Context, repo *repo_model.RepoUnit) error {
+		repoUnitCnt++
+		return nil
+	})
+	require.NoError(t, err)
+	assert.EqualValues(t, cnt, repoUnitCnt)
+
+	err = db.Iterate(db.DefaultContext, nil, func(ctx context.Context, repoUnit *repo_model.RepoUnit) error {
+		has, err := db.ExistByID[repo_model.RepoUnit](ctx, repoUnit.ID)
+		if err != nil {
+			return err
+		}
+		if !has {
+			return db.ErrNotExist{Resource: "repo_unit", ID: repoUnit.ID}
+		}
+		return nil
+	})
+	require.NoError(t, err)
+}
diff --git a/models/db/list.go b/models/db/list.go
new file mode 100644
index 0000000..5c005a0
--- /dev/null
+++ b/models/db/list.go
@@ -0,0 +1,215 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/builder"
+	"xorm.io/xorm"
+)
+
+const (
+	// DefaultMaxInSize represents default variables number on IN () in SQL
+	DefaultMaxInSize     = 50
+	defaultFindSliceSize = 10
+)
+
+// Paginator is the base for different ListOptions types
+type Paginator interface {
+	GetSkipTake() (skip, take int)
+	IsListAll() bool
+}
+
+// SetSessionPagination sets pagination for a database session
+func SetSessionPagination(sess Engine, p Paginator) *xorm.Session {
+	skip, take := p.GetSkipTake()
+
+	return sess.Limit(take, skip)
+}
+
+// ListOptions options to paginate results
+type ListOptions struct {
+	PageSize int
+	Page     int  // start from 1
+	ListAll  bool // if true, then PageSize and Page will not be taken
+}
+
+var ListOptionsAll = ListOptions{ListAll: true}
+
+var (
+	_ Paginator   = &ListOptions{}
+	_ FindOptions = ListOptions{}
+)
+
+// GetSkipTake returns the skip and take values
+func (opts *ListOptions) GetSkipTake() (skip, take int) {
+	opts.SetDefaultValues()
+	return (opts.Page - 1) * opts.PageSize, opts.PageSize
+}
+
+func (opts ListOptions) GetPage() int {
+	return opts.Page
+}
+
+func (opts ListOptions) GetPageSize() int {
+	return opts.PageSize
+}
+
+// IsListAll indicates PageSize and Page will be ignored
+func (opts ListOptions) IsListAll() bool {
+	return opts.ListAll
+}
+
+// SetDefaultValues sets default values
+func (opts *ListOptions) SetDefaultValues() {
+	if opts.PageSize <= 0 {
+		opts.PageSize = setting.API.DefaultPagingNum
+	}
+	if opts.PageSize > setting.API.MaxResponseItems {
+		opts.PageSize = setting.API.MaxResponseItems
+	}
+	if opts.Page <= 0 {
+		opts.Page = 1
+	}
+}
+
+func (opts ListOptions) ToConds() builder.Cond {
+	return builder.NewCond()
+}
+
+// AbsoluteListOptions absolute options to paginate results
+type AbsoluteListOptions struct {
+	skip int
+	take int
+}
+
+var _ Paginator = &AbsoluteListOptions{}
+
+// NewAbsoluteListOptions creates a list option with applied limits
+func NewAbsoluteListOptions(skip, take int) *AbsoluteListOptions {
+	if skip < 0 {
+		skip = 0
+	}
+	if take <= 0 {
+		take = setting.API.DefaultPagingNum
+	}
+	if take > setting.API.MaxResponseItems {
+		take = setting.API.MaxResponseItems
+	}
+	return &AbsoluteListOptions{skip, take}
+}
+
+// IsListAll will always return false
+func (opts *AbsoluteListOptions) IsListAll() bool {
+	return false
+}
+
+// GetSkipTake returns the skip and take values
+func (opts *AbsoluteListOptions) GetSkipTake() (skip, take int) {
+	return opts.skip, opts.take
+}
+
+// FindOptions represents a find options
+type FindOptions interface {
+	GetPage() int
+	GetPageSize() int
+	IsListAll() bool
+	ToConds() builder.Cond
+}
+
+type JoinFunc func(sess Engine) error
+
+type FindOptionsJoin interface {
+	ToJoins() []JoinFunc
+}
+
+type FindOptionsOrder interface {
+	ToOrders() string
+}
+
+// Find represents a common find function which accept an options interface
+func Find[T any](ctx context.Context, opts FindOptions) ([]*T, error) {
+	sess := GetEngine(ctx).Where(opts.ToConds())
+
+	if joinOpt, ok := opts.(FindOptionsJoin); ok {
+		for _, joinFunc := range joinOpt.ToJoins() {
+			if err := joinFunc(sess); err != nil {
+				return nil, err
+			}
+		}
+	}
+	if orderOpt, ok := opts.(FindOptionsOrder); ok {
+		if order := orderOpt.ToOrders(); order != "" {
+			sess.OrderBy(order)
+		}
+	}
+
+	page, pageSize := opts.GetPage(), opts.GetPageSize()
+	if !opts.IsListAll() && pageSize > 0 {
+		if page == 0 {
+			page = 1
+		}
+		sess.Limit(pageSize, (page-1)*pageSize)
+	}
+
+	findPageSize := defaultFindSliceSize
+	if pageSize > 0 {
+		findPageSize = pageSize
+	}
+	objects := make([]*T, 0, findPageSize)
+	if err := sess.Find(&objects); err != nil {
+		return nil, err
+	}
+	return objects, nil
+}
+
+// Count represents a common count function which accept an options interface
+func Count[T any](ctx context.Context, opts FindOptions) (int64, error) {
+	sess := GetEngine(ctx).Where(opts.ToConds())
+	if joinOpt, ok := opts.(FindOptionsJoin); ok {
+		for _, joinFunc := range joinOpt.ToJoins() {
+			if err := joinFunc(sess); err != nil {
+				return 0, err
+			}
+		}
+	}
+
+	var object T
+	return sess.Count(&object)
+}
+
+// FindAndCount represents a common findandcount function which accept an options interface
+func FindAndCount[T any](ctx context.Context, opts FindOptions) ([]*T, int64, error) {
+	sess := GetEngine(ctx).Where(opts.ToConds())
+	page, pageSize := opts.GetPage(), opts.GetPageSize()
+	if !opts.IsListAll() && pageSize > 0 && page >= 1 {
+		sess.Limit(pageSize, (page-1)*pageSize)
+	}
+	if joinOpt, ok := opts.(FindOptionsJoin); ok {
+		for _, joinFunc := range joinOpt.ToJoins() {
+			if err := joinFunc(sess); err != nil {
+				return nil, 0, err
+			}
+		}
+	}
+	if orderOpt, ok := opts.(FindOptionsOrder); ok {
+		if order := orderOpt.ToOrders(); order != "" {
+			sess.OrderBy(order)
+		}
+	}
+
+	findPageSize := defaultFindSliceSize
+	if pageSize > 0 {
+		findPageSize = pageSize
+	}
+	objects := make([]*T, 0, findPageSize)
+	cnt, err := sess.FindAndCount(&objects)
+	if err != nil {
+		return nil, 0, err
+	}
+	return objects, cnt, nil
+}
diff --git a/models/db/list_test.go b/models/db/list_test.go
new file mode 100644
index 0000000..82240d2
--- /dev/null
+++ b/models/db/list_test.go
@@ -0,0 +1,53 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db_test
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"xorm.io/builder"
+)
+
+type mockListOptions struct {
+	db.ListOptions
+}
+
+func (opts mockListOptions) IsListAll() bool {
+	return true
+}
+
+func (opts mockListOptions) ToConds() builder.Cond {
+	return builder.NewCond()
+}
+
+func TestFind(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	xe := unittest.GetXORMEngine()
+	require.NoError(t, xe.Sync(&repo_model.RepoUnit{}))
+
+	var repoUnitCount int
+	_, err := db.GetEngine(db.DefaultContext).SQL("SELECT COUNT(*) FROM repo_unit").Get(&repoUnitCount)
+	require.NoError(t, err)
+	assert.NotEmpty(t, repoUnitCount)
+
+	opts := mockListOptions{}
+	repoUnits, err := db.Find[repo_model.RepoUnit](db.DefaultContext, opts)
+	require.NoError(t, err)
+	assert.Len(t, repoUnits, repoUnitCount)
+
+	cnt, err := db.Count[repo_model.RepoUnit](db.DefaultContext, opts)
+	require.NoError(t, err)
+	assert.EqualValues(t, repoUnitCount, cnt)
+
+	repoUnits, newCnt, err := db.FindAndCount[repo_model.RepoUnit](db.DefaultContext, opts)
+	require.NoError(t, err)
+	assert.EqualValues(t, cnt, newCnt)
+	assert.Len(t, repoUnits, repoUnitCount)
+}
diff --git a/models/db/log.go b/models/db/log.go
new file mode 100644
index 0000000..457ee80
--- /dev/null
+++ b/models/db/log.go
@@ -0,0 +1,107 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"fmt"
+	"sync/atomic"
+
+	"code.gitea.io/gitea/modules/log"
+
+	xormlog "xorm.io/xorm/log"
+)
+
+// XORMLogBridge a logger bridge from Logger to xorm
+type XORMLogBridge struct {
+	showSQL atomic.Bool
+	logger  log.Logger
+}
+
+// NewXORMLogger inits a log bridge for xorm
+func NewXORMLogger(showSQL bool) xormlog.Logger {
+	l := &XORMLogBridge{logger: log.GetLogger("xorm")}
+	l.showSQL.Store(showSQL)
+	return l
+}
+
+const stackLevel = 8
+
+// Log a message with defined skip and at logging level
+func (l *XORMLogBridge) Log(skip int, level log.Level, format string, v ...any) {
+	l.logger.Log(skip+1, level, format, v...)
+}
+
+// Debug show debug log
+func (l *XORMLogBridge) Debug(v ...any) {
+	l.Log(stackLevel, log.DEBUG, "%s", fmt.Sprint(v...))
+}
+
+// Debugf show debug log
+func (l *XORMLogBridge) Debugf(format string, v ...any) {
+	l.Log(stackLevel, log.DEBUG, format, v...)
+}
+
+// Error show error log
+func (l *XORMLogBridge) Error(v ...any) {
+	l.Log(stackLevel, log.ERROR, "%s", fmt.Sprint(v...))
+}
+
+// Errorf show error log
+func (l *XORMLogBridge) Errorf(format string, v ...any) {
+	l.Log(stackLevel, log.ERROR, format, v...)
+}
+
+// Info show information level log
+func (l *XORMLogBridge) Info(v ...any) {
+	l.Log(stackLevel, log.INFO, "%s", fmt.Sprint(v...))
+}
+
+// Infof show information level log
+func (l *XORMLogBridge) Infof(format string, v ...any) {
+	l.Log(stackLevel, log.INFO, format, v...)
+}
+
+// Warn show warning log
+func (l *XORMLogBridge) Warn(v ...any) {
+	l.Log(stackLevel, log.WARN, "%s", fmt.Sprint(v...))
+}
+
+// Warnf show warning log
+func (l *XORMLogBridge) Warnf(format string, v ...any) {
+	l.Log(stackLevel, log.WARN, format, v...)
+}
+
+// Level get logger level
+func (l *XORMLogBridge) Level() xormlog.LogLevel {
+	switch l.logger.GetLevel() {
+	case log.TRACE, log.DEBUG:
+		return xormlog.LOG_DEBUG
+	case log.INFO:
+		return xormlog.LOG_INFO
+	case log.WARN:
+		return xormlog.LOG_WARNING
+	case log.ERROR:
+		return xormlog.LOG_ERR
+	case log.NONE:
+		return xormlog.LOG_OFF
+	}
+	return xormlog.LOG_UNKNOWN
+}
+
+// SetLevel set the logger level
+func (l *XORMLogBridge) SetLevel(lvl xormlog.LogLevel) {
+}
+
+// ShowSQL set if record SQL
+func (l *XORMLogBridge) ShowSQL(show ...bool) {
+	if len(show) == 0 {
+		show = []bool{true}
+	}
+	l.showSQL.Store(show[0])
+}
+
+// IsShowSQL if record SQL
+func (l *XORMLogBridge) IsShowSQL() bool {
+	return l.showSQL.Load()
+}
diff --git a/models/db/main_test.go b/models/db/main_test.go
new file mode 100644
index 0000000..7d80b40
--- /dev/null
+++ b/models/db/main_test.go
@@ -0,0 +1,17 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db_test
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+
+	_ "code.gitea.io/gitea/models"
+	_ "code.gitea.io/gitea/models/repo"
+)
+
+func TestMain(m *testing.M) {
+	unittest.MainTest(m)
+}
diff --git a/models/db/name.go b/models/db/name.go
new file mode 100644
index 0000000..51be33a
--- /dev/null
+++ b/models/db/name.go
@@ -0,0 +1,106 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+	"unicode/utf8"
+
+	"code.gitea.io/gitea/modules/util"
+)
+
+var (
+	// ErrNameEmpty name is empty error
+	ErrNameEmpty = util.SilentWrap{Message: "name is empty", Err: util.ErrInvalidArgument}
+
+	// AlphaDashDotPattern characters prohibited in a user name (anything except A-Za-z0-9_.-)
+	AlphaDashDotPattern = regexp.MustCompile(`[^\w-\.]`)
+)
+
+// ErrNameReserved represents a "reserved name" error.
+type ErrNameReserved struct {
+	Name string
+}
+
+// IsErrNameReserved checks if an error is a ErrNameReserved.
+func IsErrNameReserved(err error) bool {
+	_, ok := err.(ErrNameReserved)
+	return ok
+}
+
+func (err ErrNameReserved) Error() string {
+	return fmt.Sprintf("name is reserved [name: %s]", err.Name)
+}
+
+// Unwrap unwraps this as a ErrInvalid err
+func (err ErrNameReserved) Unwrap() error {
+	return util.ErrInvalidArgument
+}
+
+// ErrNamePatternNotAllowed represents a "pattern not allowed" error.
+type ErrNamePatternNotAllowed struct {
+	Pattern string
+}
+
+// IsErrNamePatternNotAllowed checks if an error is an ErrNamePatternNotAllowed.
+func IsErrNamePatternNotAllowed(err error) bool {
+	_, ok := err.(ErrNamePatternNotAllowed)
+	return ok
+}
+
+func (err ErrNamePatternNotAllowed) Error() string {
+	return fmt.Sprintf("name pattern is not allowed [pattern: %s]", err.Pattern)
+}
+
+// Unwrap unwraps this as a ErrInvalid err
+func (err ErrNamePatternNotAllowed) Unwrap() error {
+	return util.ErrInvalidArgument
+}
+
+// ErrNameCharsNotAllowed represents a "character not allowed in name" error.
+type ErrNameCharsNotAllowed struct {
+	Name string
+}
+
+// IsErrNameCharsNotAllowed checks if an error is an ErrNameCharsNotAllowed.
+func IsErrNameCharsNotAllowed(err error) bool {
+	_, ok := err.(ErrNameCharsNotAllowed)
+	return ok
+}
+
+func (err ErrNameCharsNotAllowed) Error() string {
+	return fmt.Sprintf("name is invalid [%s]: must be valid alpha or numeric or dash(-_) or dot characters", err.Name)
+}
+
+// Unwrap unwraps this as a ErrInvalid err
+func (err ErrNameCharsNotAllowed) Unwrap() error {
+	return util.ErrInvalidArgument
+}
+
+// IsUsableName checks if name is reserved or pattern of name is not allowed
+// based on given reserved names and patterns.
+// Names are exact match, patterns can be prefix or suffix match with placeholder '*'.
+func IsUsableName(names, patterns []string, name string) error {
+	name = strings.TrimSpace(strings.ToLower(name))
+	if utf8.RuneCountInString(name) == 0 {
+		return ErrNameEmpty
+	}
+
+	for i := range names {
+		if name == names[i] {
+			return ErrNameReserved{name}
+		}
+	}
+
+	for _, pat := range patterns {
+		if pat[0] == '*' && strings.HasSuffix(name, pat[1:]) ||
+			(pat[len(pat)-1] == '*' && strings.HasPrefix(name, pat[:len(pat)-1])) {
+			return ErrNamePatternNotAllowed{pat}
+		}
+	}
+
+	return nil
+}
diff --git a/models/db/paginator/main_test.go b/models/db/paginator/main_test.go
new file mode 100644
index 0000000..47993ae
--- /dev/null
+++ b/models/db/paginator/main_test.go
@@ -0,0 +1,14 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package paginator
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+)
+
+func TestMain(m *testing.M) {
+	unittest.MainTest(m)
+}
diff --git a/models/db/paginator/paginator.go b/models/db/paginator/paginator.go
new file mode 100644
index 0000000..bcda47d
--- /dev/null
+++ b/models/db/paginator/paginator.go
@@ -0,0 +1,7 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package paginator
+
+// dummy only. in the future, the models/db/list_options.go should be moved here to decouple from db package
+// otherwise the unit test will cause cycle import
diff --git a/models/db/paginator/paginator_test.go b/models/db/paginator/paginator_test.go
new file mode 100644
index 0000000..2060221
--- /dev/null
+++ b/models/db/paginator/paginator_test.go
@@ -0,0 +1,59 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package paginator
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPaginator(t *testing.T) {
+	cases := []struct {
+		db.Paginator
+		Skip  int
+		Take  int
+		Start int
+		End   int
+	}{
+		{
+			Paginator: &db.ListOptions{Page: -1, PageSize: -1},
+			Skip:      0,
+			Take:      setting.API.DefaultPagingNum,
+			Start:     0,
+			End:       setting.API.DefaultPagingNum,
+		},
+		{
+			Paginator: &db.ListOptions{Page: 2, PageSize: 10},
+			Skip:      10,
+			Take:      10,
+			Start:     10,
+			End:       20,
+		},
+		{
+			Paginator: db.NewAbsoluteListOptions(-1, -1),
+			Skip:      0,
+			Take:      setting.API.DefaultPagingNum,
+			Start:     0,
+			End:       setting.API.DefaultPagingNum,
+		},
+		{
+			Paginator: db.NewAbsoluteListOptions(2, 10),
+			Skip:      2,
+			Take:      10,
+			Start:     2,
+			End:       12,
+		},
+	}
+
+	for _, c := range cases {
+		skip, take := c.Paginator.GetSkipTake()
+
+		assert.Equal(t, c.Skip, skip)
+		assert.Equal(t, c.Take, take)
+	}
+}
diff --git a/models/db/search.go b/models/db/search.go
new file mode 100644
index 0000000..37565f4
--- /dev/null
+++ b/models/db/search.go
@@ -0,0 +1,33 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+// SearchOrderBy is used to sort the result
+type SearchOrderBy string
+
+func (s SearchOrderBy) String() string {
+	return string(s)
+}
+
+// Strings for sorting result
+const (
+	SearchOrderByAlphabetically        SearchOrderBy = "name ASC"
+	SearchOrderByAlphabeticallyReverse SearchOrderBy = "name DESC"
+	SearchOrderByLeastUpdated          SearchOrderBy = "updated_unix ASC"
+	SearchOrderByRecentUpdated         SearchOrderBy = "updated_unix DESC"
+	SearchOrderByOldest                SearchOrderBy = "created_unix ASC"
+	SearchOrderByNewest                SearchOrderBy = "created_unix DESC"
+	SearchOrderByID                    SearchOrderBy = "id ASC"
+	SearchOrderByIDReverse             SearchOrderBy = "id DESC"
+	SearchOrderByStars                 SearchOrderBy = "num_stars ASC"
+	SearchOrderByStarsReverse          SearchOrderBy = "num_stars DESC"
+	SearchOrderByForks                 SearchOrderBy = "num_forks ASC"
+	SearchOrderByForksReverse          SearchOrderBy = "num_forks DESC"
+)
+
+const (
+	// Which means a condition to filter the records which don't match any id.
+	// It's different from zero which means the condition could be ignored.
+	NoConditionID = -1
+)
diff --git a/models/db/sequence.go b/models/db/sequence.go
new file mode 100644
index 0000000..f49ad93
--- /dev/null
+++ b/models/db/sequence.go
@@ -0,0 +1,70 @@
+// Copyright 2018 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"context"
+	"fmt"
+	"regexp"
+
+	"code.gitea.io/gitea/modules/setting"
+)
+
+// CountBadSequences looks for broken sequences from recreate-table mistakes
+func CountBadSequences(_ context.Context) (int64, error) {
+	if !setting.Database.Type.IsPostgreSQL() {
+		return 0, nil
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+
+	var sequences []string
+	schema := x.Dialect().URI().Schema
+
+	sess.Engine().SetSchema("")
+	if err := sess.Table("information_schema.sequences").Cols("sequence_name").Where("sequence_name LIKE 'tmp_recreate__%_id_seq%' AND sequence_catalog = ?", setting.Database.Name).Find(&sequences); err != nil {
+		return 0, err
+	}
+	sess.Engine().SetSchema(schema)
+
+	return int64(len(sequences)), nil
+}
+
+// FixBadSequences fixes for broken sequences from recreate-table mistakes
+func FixBadSequences(_ context.Context) error {
+	if !setting.Database.Type.IsPostgreSQL() {
+		return nil
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	var sequences []string
+	schema := sess.Engine().Dialect().URI().Schema
+
+	sess.Engine().SetSchema("")
+	if err := sess.Table("information_schema.sequences").Cols("sequence_name").Where("sequence_name LIKE 'tmp_recreate__%_id_seq%' AND sequence_catalog = ?", setting.Database.Name).Find(&sequences); err != nil {
+		return err
+	}
+	sess.Engine().SetSchema(schema)
+
+	sequenceRegexp := regexp.MustCompile(`tmp_recreate__(\w+)_id_seq.*`)
+
+	for _, sequence := range sequences {
+		tableName := sequenceRegexp.FindStringSubmatch(sequence)[1]
+		newSequenceName := tableName + "_id_seq"
+		if _, err := sess.Exec(fmt.Sprintf("ALTER SEQUENCE `%s` RENAME TO `%s`", sequence, newSequenceName)); err != nil {
+			return err
+		}
+		if _, err := sess.Exec(fmt.Sprintf("SELECT setval('%s', COALESCE((SELECT MAX(id)+1 FROM `%s`), 1), false)", newSequenceName, tableName)); err != nil {
+			return err
+		}
+	}
+
+	return sess.Commit()
+}
diff --git a/models/db/sql_postgres_with_schema.go b/models/db/sql_postgres_with_schema.go
new file mode 100644
index 0000000..ec63447
--- /dev/null
+++ b/models/db/sql_postgres_with_schema.go
@@ -0,0 +1,74 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"sync"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/lib/pq"
+	"xorm.io/xorm/dialects"
+)
+
+var registerOnce sync.Once
+
+func registerPostgresSchemaDriver() {
+	registerOnce.Do(func() {
+		sql.Register("postgresschema", &postgresSchemaDriver{})
+		dialects.RegisterDriver("postgresschema", dialects.QueryDriver("postgres"))
+	})
+}
+
+type postgresSchemaDriver struct {
+	pq.Driver
+}
+
+// Open opens a new connection to the database. name is a connection string.
+// This function opens the postgres connection in the default manner but immediately
+// runs set_config to set the search_path appropriately
+func (d *postgresSchemaDriver) Open(name string) (driver.Conn, error) {
+	conn, err := d.Driver.Open(name)
+	if err != nil {
+		return conn, err
+	}
+	schemaValue, _ := driver.String.ConvertValue(setting.Database.Schema)
+
+	// golangci lint is incorrect here - there is no benefit to using driver.ExecerContext here
+	// and in any case pq does not implement it
+	if execer, ok := conn.(driver.Execer); ok { //nolint
+		_, err := execer.Exec(`SELECT set_config(
+			'search_path',
+			$1 || ',' || current_setting('search_path'),
+			false)`, []driver.Value{schemaValue})
+		if err != nil {
+			_ = conn.Close()
+			return nil, err
+		}
+		return conn, nil
+	}
+
+	stmt, err := conn.Prepare(`SELECT set_config(
+		'search_path',
+		$1 || ',' || current_setting('search_path'),
+		false)`)
+	if err != nil {
+		_ = conn.Close()
+		return nil, err
+	}
+	defer stmt.Close()
+
+	// driver.String.ConvertValue will never return err for string
+
+	// golangci lint is incorrect here - there is no benefit to using stmt.ExecWithContext here
+	_, err = stmt.Exec([]driver.Value{schemaValue}) //nolint
+	if err != nil {
+		_ = conn.Close()
+		return nil, err
+	}
+
+	return conn, nil
+}