How to delete association (many2many)? - go

Question

Strange behaviour deleting association happened.
The query generated an extra condition which i did not add.
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)
I expect the deletion to be:
[2.000ms] [rows:0] DELETE FROM `client_operators` WHERE client_id = 5 AND `client_operators`.`operator_id` = 1
OR
[2.000ms] [rows:0] DELETE FROM `client_operators` WHERE `client_operators`.`client_id` = 5 AND `client_operators`.`operator_id` = 1
However it currently does:
[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
It adds the extra condition of " AND `client_operators`.`client_id` IN (NULL) "
I tried Association().Clear() and did not do anything too.

Answer 1

This is happening because you're passing &Client{} to Model.
Looking at gorm docs you need to construct a client with a valid Id first like this:
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)