如何使用Gorm从数据库中返回新创建的记录

Question

我有一个创建新用户的函数，但是获取用户值的推定方法不包括数据库创建的自动化值（ID，create_at）

type User struct {
    Id         string `json:"id" gorm:"primaryKey"`
    Email      string `json:"email"`
    Password   string `json:"password"`
    Created_At string `json:"created_at"`
    Updated_At string `json:"updated_at"`
    Deleted_At string `json:"deleted_at"`
}

type UserRequest struct {
    Email    string `json:"email"`
    Password string `json:"password"`
}

func CreateUserRepo(newUser UserRequest) (*User, error) {

    user := User{Email: newUser.Email, Password: newUser.Password}
    fmt.Println(user)
    result := services.PostgresSQLDB.Select("Email", "Password").Create(&user)
    fmt.Println(result.RowsAffected)

    if result.Error != nil {
        modules.Logger.Error(result.Error)
        return nil, result.Error
    }

    return &user, nil

}

您可以看到我在ID和Create_at中获得一个空字符串，尽管这些值已由我的数据库自动生成。

{
    "id": "",
    "email": "[email protected]",
    "password": "password",
    "created_at": "",
    "updated_at": "",
    "deleted_at": ""
}

对某些扩展的测试

我认为这取决于编写Gorm期望的“适当”类型。

1. 如果我将gorm.model添加到我的struct中，ID似乎会返回UUID，但是它还返回了一堆我不想要的重复的字段（ID，ID，create creats created，UpdateTat，deleteTedat，deletedat，deletedat ）。删除gorm.model，id不再让我退还由Postgres

    type User struct {
        gorm.Model
        Id        uuid.UUID      `json:"id"`
        Email     string         `json:"email"`
        Password  string         `json:"password"`
        CreatedAt time.Time      `json:"created_at"`
        UpdatedAt time.Time      `json:"updated_at"`
        DeletedAt gorm.DeletedAt `json:"deleted_at"`
    }

{
    "ID": 0,
    "CreatedAt": "0001-01-01T00:00:00Z",
    "UpdatedAt": "0001-01-01T00:00:00Z",
    "DeletedAt": null,
    "id": "b4dea226-3be2-4ee7-8548-67ccbbbcbcca",
    "email": "[email protected]",
    "password": "password",
    "created_at": "2022-06-25T20:59:27.872198797+01:00",
    "updated_at": "2022-06-25T20:59:27.872198797+01:00",
    "deleted_at": null
}

数据库postgres

-- CreateTable
CREATE TABLE "users" (
    "id" UUID NOT NULL DEFAULT gen_random_uuid(),
    "email" TEXT NOT NULL,
    "password" TEXT,
    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
    "updated_at" TIMESTAMP(3) NOT NULL,
    "deleted_at" TIMESTAMP(3),

    CONSTRAINT "users_pkey" PRIMARY KEY ("id")
);

Answer 1

我终于在不包含的情况下找到了答案。

添加默认返回子句，返回所有新创建的值。
https://gorm.io/docs/update.html#returnurning -data-from-modified行

Clauses.(clause.Returning{})

model.go

type User struct {
    ID        uuid.UUID      `json:"id" gorm:"primaryKey:type:uuid"`
    Email     string         `json:"email"`
    Password  string         `json:"password"`
    CreatedAt time.Time      `json:"created_at"`
    UpdatedAt time.Time      `json:"updated_at"`
    DeletedAt gorm.DeletedAt `json:"deleted_at"`
}

repository.go

func CreateUserRepo(newUser UserRequest) (*User, error) {

    hash, errHash := modules.HashPassword(newUser.Password)

    if errHash != nil {
        return nil, errHash
    }

    user := User{Email: newUser.Email, Password: *hash}
    result := services.PostgresSQLDB.Clauses(clause.Returning{}).Select("Email", "Password").Create(&user)
    fmt.Println(result.RowsAffected)
    fmt.Println(&user)

    if result.Error != nil {
        modules.Logger.Error(result.Error)
        return nil, result.Error
    }

    return &user, nil

}

感谢@thefool评论此发现。

Answer 2

据我所知，GORM不支持其他任何对主密钥的自动增量的东西。因此，要么您将其保留在PostgreSQL侧（就像您一样），要么在创建对象之前（使用beforecreate hook）在GO中生成自己的UUID。

另外，gorm.model定义如下：

type Model struct {
  ID        uint           `gorm:"primaryKey"`
  CreatedAt time.Time
  UpdatedAt time.Time
  DeletedAt gorm.DeletedAt `gorm:"index"`
}

您不必使用它，但是如果不使用，请添加gorm：“ primarykey”关键字段。默认情况下，主字段具有自动增量，就您的情况而言，我建议使用自动启动：false将其禁用。

type User struct {
    Id        uuid.UUID      `gorm:"primaryKey;autoIncrement:false" json:"id"`
    Email     string         `json:"email"`
    Password  string         `json:"password"`
}

当您让PostgreSQL处理默认值（而不是GORM）时，您必须再次查询对象，以访问您的ID UUID和create_at_at timestamp。

另请注意，您可以使用gormvaluerinterface在创建时使用SQL Expr。但是您仍然需要再次查询您的记录。 （ https://gorm.io/data_io/data_types.htata_types.htmll#gormvalumvaluervalueririnterface ）

in您有兴趣处理所有问题的情况，这里有一个带有和没有gorm.model的示例。

package main

import (
    "fmt"
    "time"

    "github.com/google/uuid"
    "gorm.io/driver/sqlite"
    "gorm.io/gorm"
)

var DB *gorm.DB

type User struct {
    UUID      uuid.UUID `gorm:"primaryKey;autoIncrement:false"`
    Name      string
    CreatedAt time.Time
}

type UserWithGormModel struct {
    gorm.Model
    UUID uuid.UUID `gorm:"primaryKey;autoIncrement:false"`
    Name string
}

func (u *User) BeforeCreate(tx *gorm.DB) (err error) {

    // This is an example, refer to https://pkg.go.dev/github.com/google/UUID for good usage
    u.UUID = uuid.New()

    u.CreatedAt = time.Now()

    return
}

func (u *UserWithGormModel) BeforeCreate(tx *gorm.DB) (err error) {

    // This is an example, refer to https://pkg.go.dev/github.com/google/UUID for good usage
    u.UUID = uuid.New()

    return
}

func ConnectDatabase() {

    database, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{})
    if err != nil {
        panic("failed to connect database")
    }

    if err != nil {
        panic("Failed to connect to database!")
    }

    database.AutoMigrate(&User{}, &UserWithGormModel{})

    DB = database
}

func main() {
    ConnectDatabase()

    user := User{Name: "Bob"}
    DB.Create(&user)
    fmt.Printf("User{UUID: %s, User.Name: %s, CreatedAt: %s}\n", user.UUID, user.Name, user.CreatedAt)

    user2 := UserWithGormModel{Name: "John"}
    DB.Create(&user2)
    fmt.Printf("UserWithGormModel{UUID: %s, Name: %s, CreatedAt: %s}\n", user2.UUID, user2.Name, user2.CreatedAt)
}

输出：

User{UUID: 8551636a-540f-4733-8179-3f0cc45daf4f, User.Name: Bob, CreatedAt: 2022-06-28 11:40:10.9225724 +0200 CEST}
UserWithGormModel{UUID: 2a6f94bd-a42b-4316-90be-0e93ea5091a6, Name: John, CreatedAt: 2022-06-28 11:40:10.9318004 +0200 CEST}

Answer 3

我希望它能有所帮助

var data map[string]interface{}
err := DB.Model(models.User{}).Clauses(clause.Returning{}).Create(data).Error
if err != nil {
    return models.User{}, err
}

id := fmt.Sprint(data["id"])
var user models.User
DB.First(&user, id)
return user, nil