ent 生成的代码中client 提供了比较全的事务处理
启动单个事务进行处理
// GenTx generates group of entities in a transaction.
func GenTx(ctx context.Context, client *ent.Client) error {
tx, err := client.Tx(ctx)
if err != nil {
return fmt.Errorf("starting a transaction: %v", err)
}
hub, err := tx.Group.
Create().
SetName("Github").
Save(ctx)
if err != nil {
return rollback(tx, fmt.Errorf("failed creating the group: %v", err))
}
// Create the admin of the group.
dan, err := tx.User.
Create().
SetAge(29).
SetName("Dan").
AddManage(hub).
Save(ctx)
if err != nil {
return rollback(tx, err)
}
// Create user "Ariel".
a8m, err := tx.User.
Create().
SetAge(30).
SetName("Ariel").
AddGroups(hub).
AddFriends(dan).
Save(ctx)
if err != nil {
return rollback(tx, err)
}
fmt.Println(a8m)
// Output:
// User(id=2, age=30, name=Ariel)
// Commit the transaction.
return tx.Commit()
}
// rollback calls to tx.Rollback and wraps the given error
// with the rollback error if occurred.
func rollback(tx *ent.Tx, err error) error {
if rerr := tx.Rollback(); rerr != nil {
err = fmt.Errorf("%v: %v", err, rerr)
}
return err
}
事务client 封装
有时已经使用了 *ent.Client 但是我们需要支持事务，就可以使用次方法
// WrapGen wraps the existing "Gen" function in a transaction.
func WrapGen(ctx context.Context, client *ent.Client) error {
tx, err := client.Tx(ctx)
if err != nil {
return err
}
txClient := tx.Client()
// Use the "Gen" below, but give it the transactional client; no code changes to "Gen".
if err := Gen(ctx, txClient); err != nil {
return rollback(tx, err)
}
return tx.Commit()
}
// Gen generates a group of entities.
func Gen(ctx context.Context, client *ent.Client) error {
// ...
return nil
}
最佳实践
- 一个可重用的事务帮助方法
func WithTx(ctx context.Context, client *ent.Client, fn func(tx *ent.Tx) error) error {
tx, err := client.Tx(ctx)
if err != nil {
return err
}
defer func() {
if v := recover(); v != nil {
tx.Rollback()
panic(v)
}
}()
if err := fn(tx); err != nil {
if rerr := tx.Rollback(); rerr != nil {
err = errors.Wrapf(err, "rolling back transaction: %v", rerr)
}
return err
}
if err := tx.Commit(); err != nil {
return errors.Wrapf(err, "committing transaction: %v", err)
}
return nil
}
- 使用
func Do(ctx context.Context, client *ent.Client) {
// WithTx helper.
if err := WithTx(ctx, client, func(tx *ent.Tx) error {
return Gen(ctx, tx.Client())
}); err != nil {
log.Fatal(err)
}
}