go - 无法将 txdb 与 Gormigrate 一起使用

Question

我正在尝试使用 txdb用于在隔离事务内迁移我的数据库，用于测试与数据库交互的代码以及测试迁移本身。但每次我运行代码时都会返回错误，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/<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="680f071a05010f1a091c0d461e59281e59465e4658" rel="noreferrer noopener nofollow">[email protected]</a>/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，here is the repository with the code还有 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: %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，您需要使用已知的方言名称作为第一个参数，在本例中您需要“postgres”，因为您将使用 postgresql 作为底层数据库因此你需要 gorm 使用相应的 sql 方言。

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: %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，您可以直接传递gorm.Open *sql.Db，相关部分如下:

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

那也行。