Go 是数据一种年轻而强大的语言，专为编写小型、库事简单的数据服务而创建。但随着时间推移，库事越来越多复杂应用和系统也在采用 Go 进行开发，数据这就出现了一些问题：如何处理事务？库事

为了深入探讨这个问题，我们假设一个简单的数据业务场景：用户注册。

作为一个系统，库事我希望在注册时创建用户和个人资料。数据

RDBMS/DBMS 的库事现代 Go 库不像 C# 和 Java 的 Hibernate、Entity Framework 那样强大，数据因此我们必须自己处理。库事为了实现用户注册业务场景，数据我们将创建并评估几种处理事务的站群服务器库事方法。

由于每种事务处理方法都必须与 sql.DB 和 sql.Tx 配合使用，数据因此需要引入接口来封装对数据库的访问。

生成的应用有两个域实体和一个用于访问数据库的 DB 低级接口。

复制package model type User struct { Email string } type Profile struct { Name string }1.2.3.4.5.6.7.8.9. 复制package transaction type DB interface { QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error) ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error) PrepareContext(ctx context.Context, query string) (*sql.Stmt, error) }1.2.3.4.5.6.7.8.

准备工作完成后，就可以采用如下两种方法。

1. 事务感知上下文

工作原理：transaction.Manager启动事务并将其放入上下文。当存储库执行查询时，助手会检查上下文中是否有事务，并使用创建的事务来执行查询，或者如果上下文为空，则不使用事务来执行查询。

为了启动事务，我们需要实体：Manager

复制package transaction type Manager interface { Run( ctx context.Context, callback func(ctx context.Context) error, ) error }1.2.3.4.5.6.7.8.

transaction.Manager 实现：

复制package transaction import ( "context" "database/sql" "github.com/pkg/errors" "go.uber.org/multierr" ) type txKey string var ctxWithTx = txKey("tx") type SQLTransactionManager struct { db *sql.DB } func NewManager(db *sql.DB) *SQLTransactionManager { return &SQLTransactionManager{db: db} } func (m *SQLTransactionManager) Run( ctx context.Context, callback func(ctx context.Context) error, ) (rErr error) { tx, err := m.db.BeginTx(ctx, &sql.TxOptions{}) if err != nil { return errors.WithStack(err) } defer func() { if rErr != nil { rErr = multierr.Combine(rErr, errors.WithStack(tx.Rollback())) } }() defer func() { if rec := recover(); rec != nil { if e, ok := rec.(error); ok { rErr = e } else { rErr = errors.Errorf("%s", rec) } } }() if err = callback(putTxToContext(ctx, tx)); err != nil { return err } return errors.WithStack(tx.Commit()) } func ExtractTxFromContext(ctx context.Context) (*sql.Tx, bool) { tx := ctx.Value(ctxWithTx) if t, ok := tx.(*sql.Tx); ok { return t, true } return nil, false } func putTxToContext(ctx context.Context, tx *sql.Tx) context.Context { return context.WithValue(ctx, ctxWithTx, tx) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39.40.41.42.43.44.45.46.47.48.49.50.51.52.53.54.55.56.57.58.59.60.61.62.63.64.65.66.

DB实现：

复制package storage import ( "brand/transaction/example1/transaction" "context" "database/sql" ) type DB struct { db *sql.DB } func NewDB(db *sql.DB) *DB { return &DB{db: db} } func (d *DB) QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row { tx, ok := transaction.ExtractTxFromContext(ctx) if !ok { return d.db.QueryRowContext(ctx, query, args...) } return tx.QueryRowContext(ctx, query, args...) } func (d *DB) QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error) { tx, ok := transaction.ExtractTxFromContext(ctx) if !ok { return d.db.QueryContext(ctx, query, args...) } return tx.QueryContext(ctx, query, args...) } func (d *DB) ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error) { tx, ok := transaction.ExtractTxFromContext(ctx) if !ok { return d.db.ExecContext(ctx, query, args...) } return tx.ExecContext(ctx, query, args...) } func (d *DB) PrepareContext(ctx context.Context, query string) (*sql.Stmt, error) { tx, ok := transaction.ExtractTxFromContext(ctx) if !ok { return d.db.PrepareContext(ctx, query) } return tx.PrepareContext(ctx, query) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39.40.41.42.43.44.45.46.47.48.49.50.51.

RegistrationService 负责用户注册业务场景

复制package service import ( "brand/transaction/example1/model" "brand/transaction/example1/transaction" "context" ) type UserRepository interface { Create(ctx context.Context, user *model.User) error } type ProfileRepository interface { Create(ctx context.Context, user *model.Profile) error } type RegistrationData struct { Email string Name string } type RegistrationService struct { transactionManager transaction.Manager userRepository UserRepository profileRepository ProfileRepository } func NewRegistrationService( transactionManager transaction.Manager, userRepository UserRepository, profileRepository ProfileRepository, ) *RegistrationService { return &RegistrationService{ transactionManager: transactionManager, userRepository: userRepository, profileRepository: profileRepository, } } func (s *RegistrationService) Register(ctx context.Context, data RegistrationData) error { return s.transactionManager.Run(ctx, func(ctx context.Context) error { if err := s.userRepository.Create(ctx, &model.User{ Email: data.Email, }); err != nil { return err } if err := s.profileRepository.Create(ctx, &model.Profile{ Name: data.Name, }); err != nil { return err } return nil }) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39.40.41.42.43.44.45.46.47.48.49.50.51.52.53.54.55.56.

User和ProfileRepository的亿华云实现：

复制package storage import ( "brand/transaction" "brand/transaction/example1/model" "context" ) type ProfileRepository struct { db transaction.DB } func NewProfileRepository(db transaction.DB) *ProfileRepository { return &ProfileRepository{db: db} } func (r *ProfileRepository) Create(ctx context.Context, profile *model.Profile) error { _, err := r.db.ExecContext(ctx, "INSERT ...", profile.Name) return err }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21. 复制package storage import ( "brand/transaction" "brand/transaction/example1/model" "context" ) type UserRepository struct { db transaction.DB } func NewUserRepository(db transaction.DB) *UserRepository { return &UserRepository{db: db} } func (r *UserRepository) Create(ctx context.Context, user *model.User) error { _, err := r.db.ExecContext(ctx, "INSERT ...", user.Email) return err }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.

优点：

简单：存储库会自动使用由 TransactionManager 启动的事务与存储无关：客户端代码对存储类型一无所知

缺点

不符合Go的使用习惯控制较少：无法防止在事务中启动事务，可能会产生意想不到的副作用，代码审查时必须考虑到这一点2. 事务感知存储库

工作原理：事务管理器启动事务并将事务放入回调，存储库工厂方法使用事务创建自己。

为了启动事务，我们需要实体：Manager

复制type Manager interface { Run( ctx context.Context, callback func(ctx context.Context, tx *sql.Tx) error, ) error }1.2.3.4.5.6.

transaction.Manager 实现：

复制package transaction import ( "context" "database/sql" "github.com/pkg/errors" "go.uber.org/multierr" ) type txKey string var ctxWithTx = txKey("tx") type SQLTransactionManager struct { db *sql.DB } func NewManager(db *sql.DB) *SQLTransactionManager { return &SQLTransactionManager{db: db} } func (m *SQLTransactionManager) Run( ctx context.Context, callback func(ctx context.Context, tx *sql.Tx) error, ) (rErr error) { tx, err := m.db.BeginTx(ctx, &sql.TxOptions{}) if err != nil { return errors.WithStack(err) } defer func() { if rErr != nil { rErr = multierr.Combine(rErr, errors.WithStack(tx.Rollback())) } }() defer func() { if rec := recover(); rec != nil { if e, ok := rec.(error); ok { rErr = e } else { rErr = errors.Errorf("%s", rec) } } }() if err = callback(ctx, tx); err != nil { return err } return errors.WithStack(tx.Commit()) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39.40.41.42.43.44.45.46.47.48.49.50.51.52.

DB实现：

复制package storage import ( "context" "database/sql" ) type DB struct { db *sql.DB } func NewDB(db *sql.DB) *DB { return &DB{db: db} } func (d *DB) QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row { return d.db.QueryRowContext(ctx, query, args...) } func (d *DB) QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error) { return d.db.QueryContext(ctx, query, args...) } func (d *DB) ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error) { return d.db.ExecContext(ctx, query, args...) } func (d *DB) PrepareContext(ctx context.Context, query string) (*sql.Stmt, error) { return d.db.PrepareContext(ctx, query) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.

RegistrationService 负责用户注册业务场景

有两种方法可以创建带有事务的存储库：

存储库带有结构方法 WithTransaction（示例中使用了该方法）存储库工厂 userRepositoryFactory.CreateFromTransaction(tx) 复制package service import ( "brand/transaction/example2/model" "brand/transaction/example2/transaction" "context" "database/sql" ) type UserRepository interface { Create(ctx context.Context, user *model.User) error WithTransaction(tx *sql.Tx) UserRepository } type ProfileRepository interface { Create(ctx context.Context, user *model.Profile) error WithTransaction(tx *sql.Tx) ProfileRepository } type RegistrationData struct { Email string Name string } type RegistrationService struct { transactionManager transaction.Manager userRepository UserRepository profileRepository ProfileRepository } func NewRegistrationService( transactionManager transaction.Manager, userRepository UserRepository, profileRepository ProfileRepository, ) *RegistrationService { return &RegistrationService{ transactionManager: transactionManager, userRepository: userRepository, profileRepository: profileRepository, } } func (s *RegistrationService) Register(ctx context.Context, data RegistrationData) error { return s.transactionManager.Run(ctx, func(ctx context.Context, tx *sql.Tx) error { userRepository := s.userRepository.WithTransaction(tx) profileRepository := s.profileRepository.WithTransaction(tx) if err := userRepository.Create(ctx, &model.User{ Email: data.Email, }); err != nil { return err } if err := profileRepository.Create(ctx, &model.Profile{ Name: data.Name, }); err != nil { return err } return nil }) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39.40.41.42.43.44.45.46.47.48.49.50.51.52.53.54.55.56.57.58.59.60.61.62.

User和ProfileRepository的实现：

复制package storage import ( "brand/transaction" "brand/transaction/example2/model" "brand/transaction/example2/service" "context" "database/sql" ) type ProfileRepository struct { db transaction.DB } func NewProfileRepository(db transaction.DB) *ProfileRepository { return &ProfileRepository{db: db} } func (r *ProfileRepository) Create(ctx context.Context, profile *model.Profile) error { _, err := r.db.ExecContext(ctx, "INSERT ...", profile.Name) return err } func (r *ProfileRepository) WithTransaction(tx *sql.Tx) service.ProfileRepository { return NewProfileRepository(tx) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27. 复制package storage import ( "brand/transaction" "brand/transaction/example2/model" "brand/transaction/example2/service" "context" "database/sql" ) type UserRepository struct { db transaction.DB } func NewUserRepository(db transaction.DB) *UserRepository { return &UserRepository{db: db} } func (r *UserRepository) Create(ctx context.Context, user *model.User) error { _, err := r.db.ExecContext(ctx, "INSERT ...", user.Email) return err } func (r *UserRepository) WithTransaction(tx *sql.Tx) service.UserRepository { return NewUserRepository(tx) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.

优点：

更明确：在注册服务内部创建事务，可避免副作用

缺点：

客户端代码知道存储类型客户端代码负责创建新的存储库

我相信任何一种方法都能使代码更易读、更简单，但建议使用第一种方法，从而可以隐藏存储细节，使我们能够在一个项目中使用多个存储，而无需考虑实现和存储细节。

复制package storage import ( "brand/transaction" "brand/transaction/example2/model" "brand/transaction/example2/service" "context" "database/sql" ) type UserRepository struct { db transaction.DB } func NewUserRepository(db transaction.DB) *UserRepository { return &UserRepository{db: db} } func (r *UserRepository) Create(ctx context.Context, user *model.User) error { _, err := r.db.ExecContext(ctx, "INSERT ...", user.Email) return err } func (r *UserRepository) WithTransaction(tx *sql.Tx) service.UserRepository { return NewUserRepository(tx) }1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.云南idc服务商