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go - Gorm 关联 BeforeCreate 回调未按预期工作

问题描述

我有Customer结构

type Customer struct {
    Model
    Email                 string     `json:"email,omitempty"`
    Addresses             []Address
}

func (c *Customer) BeforeCreate() (err error) {
    if err := c.GenerateID(); err != nil {
        return err
    }
    return c.Marshal()
}

和Address结构

type Address struct {
    Model
    CustomerID         string
    Address1           string
}

func (a *Address) BeforeCreate() error {
// The ID is still generated, but the insert query has no `id` in it
    if err := a.GenerateID(); err != nil {
        return err
    }
    return nil
}

Model结构

type Model struct {
    ID        string `gorm:"primary_key;type:varchar(100)"`
    CreatedAt time.Time
    UpdatedAt time.Time
    DeletedAt *time.Time `sql:"index"`
}

func (model *Model) GenerateID() error {
    uv4, err := uuid.NewV4()
    if err != nil {
        return err
    }
    model.ID = uv4.String()
    return nil
}

一个客户：

customer := &model.Customer{
    Email:     "a",
    Addresses: []model.Address{
        {
            Address1: "abc street",
        },
    },
}


if err := gormDb.Create(customer).Error; err != nil {
    return nil, err
}

I got an error: Error 1364: Field 'id' doesn't have a default value对于地址对象

但是，如果我删除这些Address关联，一切都会奏效。并Id生成客户。

    customer := & model.Customer{
    Email:     "a",
    //Addresses: []model.Address{
        //{
            //Address1: "abc street",
        //},
    //},
}

如何保持Address关联并成功插入，并且仍然使用这种 ID 生成机制？

标签： gogo-gorm

解决方案

您可以使用scope.SetColumn在BeforeCreate钩子中设置字段的值

func (a *Address) BeforeCreate(scope *gorm.Scope) error {
  scope.SetColumn("ID", uuid.New())
  return nil
}

参考：https ://v1.gorm.io/docs/create.html#Setting-Field-Values-In-Hooks

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