不能将 txdb 与 Gormigrate 一起使用

Question

我正在尝试使用 txdb 在隔离事务中迁移我的数据库，以测试与数据库交互的代码以及与迁移本身的测试。但是每次我运行代码时都会返回一个错误，并且 Gorm 会发出一些警告：

$ DATABASE_URL="postgres://postgres@localhost:5432/postgres?sslmode=disable" ./txdb_ejemplo
`txdb_postgres` is not officially supported, running under compatibility mode.
(/home/jorge/go/pkg/mod/gopkg.in/gormigrate.v1@v1.6.0/gormigrate.go:381)
[2019-08-12 19:46:28]  pq: current transaction is aborted, commands ignored until end of transaction block
panic: migration failed: pq: current transaction is aborted, commands ignored until end of transaction block
goroutine 1 [running]:
main.main()
/home/jorge/proyectos/kue/fero/txdb_ejemplo/main.go:76 +0x3a1

这是运行提供数据库的 docker 服务的输出：

db_1  | 2019-08-13 01:46:08.788 UTC [1] LOG:  database system is ready to accept connections
db_1  | 2019-08-13 01:46:28.564 UTC [48] ERROR:  function database() does not exist at character 8
db_1  | 2019-08-13 01:46:28.564 UTC [48] HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
db_1  | 2019-08-13 01:46:28.564 UTC [48] STATEMENT:  SELECT DATABASE()
db_1  | 2019-08-13 01:46:28.564 UTC [48] ERROR:  syntax error at or near "AND" at character 71
db_1  | 2019-08-13 01:46:28.564 UTC [48] STATEMENT:  SELECT count(*) FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = ? AND table_name = ?
db_1  | 2019-08-13 01:46:28.564 UTC [48] ERROR:  current transaction is aborted, commands ignored until end of transaction block
db_1  | 2019-08-13 01:46:28.564 UTC [48] STATEMENT:  CREATE TABLE migrations (id VARCHAR(255) PRIMARY KEY)

我不明白我做错了什么，但我提供了一个最小的功能示例来重现我遇到的问题，这是带有代码的存储库，还有一个 Go 代码的入门：

package main
import (
"fmt"
"os"
"time"
"github.com/DATA-DOG/go-txdb"
"github.com/jinzhu/gorm"
_ "github.com/lib/pq"
gormigrate "gopkg.in/gormigrate.v1"
)
var (
migration_1 = func(tx *gorm.DB) error {
type Person struct {
gorm.Model
Name string
}
return tx.CreateTable(&Person{}).Error
}
migration_2 = func(tx *gorm.DB) error {
type Person struct {
Age int
}
return tx.AutoMigrate(&Person{}).Error
}
return_nil = func(tx *gorm.DB) error {
return nil
}
)
type Person struct {
gorm.Model
Name string
Age  int
}
func MigrateAll(gdb *gorm.DB) error {
m := gormigrate.New(gdb, gormigrate.DefaultOptions, []*gormigrate.Migration{
{
ID:       "first",
Migrate:  migration_1,
Rollback: return_nil,
},
{
ID:       "second",
Migrate:  migration_2,
Rollback: return_nil,
},
})
return m.Migrate()
}
func main() {
url := os.Getenv("DATABASE_URL")
txdb.Register("txdb_postgres", "postgres", url)
var db *gorm.DB
var err error
for i := 0; i < 3; i++ {
db, err = gorm.Open("txdb_postgres", "tx_1")
if err == nil {
break
}
fmt.Printf("connection failed, retrying in 10 seconds. Reason: %sn", err)
time.Sleep(10 * time.Second)
}
if err != nil {
panic(fmt.Sprintf("connection failed: %s", err))
}
defer db.Close()
err = MigrateAll(db)
if err != nil {
panic(fmt.Sprintf("migration failed: %s", err))
}
}

Answer 1

问题在于gorm使用第一个gorm.Open参数作为方言名称(它具有一组预定义的方言)，而不是作为database/sql驱动程序名称。

因此，您需要使用gorm已知的方言名称作为第一个参数，在这种情况下，您需要"postgres"，因为您将使用 postgresql 作为底层数据库，因此您需要使用相应的 sql 方言gorm。

然后告诉gorm使用"txdb"驱动程序和"tx_1"作为连接 URL。

这似乎有效：

package main
import (
"fmt"
"os"
"time"
"github.com/DATA-DOG/go-txdb"
"github.com/jinzhu/gorm"
_ "github.com/lib/pq"
gormigrate "gopkg.in/gormigrate.v1"
)
var (
migration_1 = func(tx *gorm.DB) error {
type Person struct {
gorm.Model
Name string
}
return tx.CreateTable(&Person{}).Error
}
migration_2 = func(tx *gorm.DB) error {
type Person struct {
Age int
}
return tx.AutoMigrate(&Person{}).Error
}
return_nil = func(tx *gorm.DB) error {
return nil
}
)
type Person struct {
gorm.Model
Name string
Age  int
}
func MigrateAll(gdb *gorm.DB) error {
m := gormigrate.New(gdb, gormigrate.DefaultOptions, []*gormigrate.Migration{
{
ID:       "first",
Migrate:  migration_1,
Rollback: return_nil,
},
{
ID:       "second",
Migrate:  migration_2,
Rollback: return_nil,
},
})
return m.Migrate()
}
func main() {
url := os.Getenv("DATABASE_URL")
txdb.Register("txdb", "postgres", url)
var db *gorm.DB
var err error
for i := 0; i < 3; i++ {
db, err = gorm.Open("postgres", "txdb", "tx_1")
if err == nil {
break
}
fmt.Printf("connection failed, retrying in 10 seconds. Reason: %sn", err)
time.Sleep(10 * time.Second)
}
if err != nil {
panic(fmt.Sprintf("connection failed: %s", err))
}
defer db.Close()
err = MigrateAll(db)
if err != nil {
panic(fmt.Sprintf("migration failed: %s", err))
}
}

或者，您可以直接gorm.Open传递*sql.Db，相关部分如下所示：

s, err := sql.Open("txdb", "tx_1")
// handle err
db, err := gorm.Open("postgres", s)
// handle err

那也行得通。