当`gorm.Model`未嵌入时GORM恐慌

Question

这是我的模型。请注意，我不想将gorm.Model嵌入到结构中。

type Order struct {
    OrderID   uint64     `gorm:"column:order_id" gorm:"primaryKey" gorm:"unique"`
    Cart      Cart       `gorm:"foreignKey:UserID"`
    CreatedBy UserID     `gorm:"index"`
    CreatedAt *time.Time `gorm:"autoCreateTime:nano"`
    UpdatedAt *time.Time `gorm:"autoUpdateTime:nano"`
    DeletedAt *time.Time
}

type Category struct {
    ID        uint64     `gorm:"column:category_id" gorm:"primaryKey" gorm:"unique"`
    Name      string     `gorm:"index"`
    Image     string     
    Products  []Product  `gorm:"foreignKey:product_id" gorm:"constraint:OnUpdate:CASCADE,OnDelete:CASCADE;"`
    CreatedBy UserID     `gorm:"index" gorm:"type:bytea"`
    CreatedAt *time.Time `gorm:"autoCreateTime:nano"`
    UpdatedAt *time.Time `gorm:"autoUpdateTime:nano"`
    DeletedAt *time.Time 
}

type Cart struct {
    UserID    UserID     `gorm:"column:user_id" gorm:"primaryKey"`
    Products  []Product  `gorm:"foreignKey:ID"`
    Price     float64   
    CreatedAt *time.Time `gorm:"autoCreateTime:nano"`
    UpdatedAt *time.Time `gorm:"autoUpdateTime:nano"`
    DeletedAt *time.Time 
}

type Product struct {
    ID        uint64     `gorm:"column:product_id" gorm:"primaryKey" gorm:"unique"`
    Name      string     `gorm:"index"`
    Price     float64    `gorm:"index"`
    Rating    uint       `gorm:"index"`
    Image     string     
    CreatedBy UserID     `gorm:"index" gorm:"type:bytea"`
    CreatedAt *time.Time `gorm:"autoCreateTime:nano"`
    UpdatedAt *time.Time `gorm:"autoUpdateTime:nano"`
    DeletedAt *time.Time 
}

当我使用AutoMigrate时，我会得到以下错误：

[error] invalid field found for struct moonspace/model.Cart's field Products: define a valid foreign key for relations or implement the Valuer/Scanner interface

我尝试过将foreignKey:UserID更改为foreignKey:user_id，但是错误仍然是一样的。

这是我的自动迁移：

func createPostgresCLI(cfg types.Config, config ...any) *gorm.DB {
    db, err := gorm.Open(postgres.Open(cfg.Url))
    if err != nil {
        panic(err)
    }

    err = db.AutoMigrate(&model.Order{}, &model.Cart{}, &model.Category{}, &model.Product{})
    if err != nil {
        panic(fmt.Errorf("Error creating database: %w", err))
    }

    return db
}

我做错了什么？另外，当我使用gorm.Model时，当我试图将一个Product插入到一个Category中时，我会得到一个外键约束错误。我正试图通过联想来添加它。

Answer 1

类别<==>产品：产品中需要包含外键列，该列将引用类别ID。在工作时，CUrrent配置将使用类别ID更新产品ID，这将是错误的

type Category struct {
    ID       uint64 `gorm:"column:category_id;primaryKey"`
    Products  []Product  `gorm:"foreignKey:CategoryID" gorm:"constraint:OnUpdate:CASCADE,OnDelete:CASCADE;"`
    ....
}

type Product struct {
    ID        uint64     `gorm:"column:product_id" gorm:"primaryKey" gorm:"unique"`
    CategoryID uint64 // New field to hold category ID.
    ....
}

Cart <===> products关系可以建模为带有连接表的many2many，以存储产品和手推车的ID，这里可能不需要外键。

type Cart struct {
    CartID   uint64 `gorm:"primaryKey"`
    Products []Product `gorm:"many2many:cart_products"`
    ....
}

还可以使用将所有gorm标记合并为一个，不需要重复。