Question

我正在尝试使用txdb在隔离的事务中迁移数据库，以测试与数据库交互的代码以及进行迁移本身的测试。但是每次我运行代码时，都会返回一个错误，并且Gorm会大喊一些警告：

$ 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

这是正在运行的提供数据库的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)

我不知道我在做什么错，但是我提供了一个最小的功能示例，该示例重现了我遇到的问题，here is the repository with the code，并且提供了Go代码的入门知识：

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: %s\n", 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

问题似乎是，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），而不是将其用作database/sql驱动程序名称。

因此，您需要使用一个已知的方言名称gorm作为第一个参数，在这种情况下，您需要"postgres"，因为您将使用postgresql作为基础数据库，因此您需要gorm使用相应的sql方言。

然后，您告诉gorm使用"txdb"驱动程序和"tx_1"作为连接URL。

这似乎可行：

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: %s\n", 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，您可以直接将gorm.Open传递给*sql.Db，相关部分将是：

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

那也行。

不能在Gormigrate中使用txdb

1 个答案: