如何删除关联（many2many）？

Question

删除关联的奇怪行为发生了。 该查询生成了一个我没有添加的额外条件。

type Client struct {
    gorm.Model
    Name        string      `gorm:"unique;not null" validate:"required,min=1,max=30"`
    Kyc_status  string      `gorm:"not null" validate:"required,min=1,max=30"`
    Kyc_remarks string      `gorm:"default:null" validate:"omitempty,min=0,max=200"`
    Operators   []*Operator `gorm:"many2many:client_operators;"`
    Op_ids      []string    `gorm:"-:all" validate:"omitempty,dive,numeric"` // placeholder field, wont be part of table
}
type Operator struct {
    gorm.Model
    Title       string    `gorm:"unique;not null" validate:"required,min=1,max=100"`
    Email       string    `gorm:"not null" validate:"required,email"`
    Mobile      string    `gorm:"not null" validate:"required,min=7,max=15,numeric"`
    Last_online time.Time `gorm:"default:null" validate:"omitempty"`
    Last_ip     string    `gorm:"default:null" validate:"omitempty,ip"`
    Clients     []*Client `gorm:"many2many:client_operators;"`
    Cli_ids     []string  `gorm:"-:all" validate:"omitempty,dive,numeric"`
}

// find operators related to client
var client_query *Client
DBconnection.Where("id = ?", pk).Preload("Operators").First(&client_query)

// delete operators related to client
DBconnection.Model(&Client{}).Where("client_id = ?", pk).Association("Operators").Delete(&client_query.Operators)

我预计删除内容为：

[2.000ms] [行数：0] DELETE FROM `client_operators` WHERE client_id = 5 AND `client_operators`.`operator_id` = 1

OR

[2.000ms] [行数： 0] 从“client_operators”中删除“client_operators”。“client_id”= 5 并且`client_operators`.`operator_id` = 1

但目前是这样的：

[2.000ms] [rows:0] DELETE FROM `client_operators` WHERE client_id = 5 AND `client_operators`.`client_id` IN (NULL) AND `client_operators`.`operator_id` = 1

它添加了额外条件 " AND `client_operators`.`client_id` IN (NULL) "

我尝试了 Association().Clear() 但也没有做任何事情。

Answer 1

发生这种情况是因为您将 &Client{} 传递给 Model。

查看 gorm 文档 您需要使用有效的 构建一个客户端Id 首先是这样的：

type Client struct {
    gorm.Model
    Name        string      `gorm:"unique;not null" validate:"required,min=1,max=30"`
    Kyc_status  string      `gorm:"not null" validate:"required,min=1,max=30"`
    Kyc_remarks string      `gorm:"default:null" validate:"omitempty,min=0,max=200"`
    Operators   []*Operator `gorm:"many2many:client_operators;"`
    Op_ids      []string    `gorm:"-:all" validate:"omitempty,dive,numeric"` // placeholder field, wont be part of table
}
type Operator struct {
    gorm.Model
    Title       string    `gorm:"unique;not null" validate:"required,min=1,max=100"`
    Email       string    `gorm:"not null" validate:"required,email"`
    Mobile      string    `gorm:"not null" validate:"required,min=7,max=15,numeric"`
    Last_online time.Time `gorm:"default:null" validate:"omitempty"`
    Last_ip     string    `gorm:"default:null" validate:"omitempty,ip"`
    Clients     []*Client `gorm:"many2many:client_operators;"`
    Cli_ids     []string  `gorm:"-:all" validate:"omitempty,dive,numeric"`
}

// find operators related to client
var client_query *Client
DBconnection.Where("id = ?", pk).Preload("Operators").First(&client_query)



// delete operators related to client
DBconnection.Model(&Client{ID: pk}).Association("Operators").Delete(&client_query.Operators)