How can I preload with specific Model?

[plusiv]

Having the follow example:

type User struct {
  gorm.Model
  Username string
  Orders   []Order
}

type CustomUserRes struct {
  Username string // <--- No gorm default fields required
  Orders   []Order
}

type Order struct {
  gorm.Model
  UserID uint `json:"user_id"`
  Price  float64
  Detail string
}

type CustomOrderRes {
  UserID uint `json:"user_id_custom"` // <--- Custom json key name
  Price  float64
  // Detail string <--- Notice that Detail Attribute is not required here
}

How can I query a user with all its Orders but using the custom model of CustomOrderRes in the preload.

I tried something like but didn't work:

var user User
var userCustom CustomUserRes
var ordersCustom CustomOrderRes

db.Preload("Order", func (tx *gorm.DB) *gorm.DB {
  return tx.Scan(&ordersCustom) // <--- I want to fit the preload result to ordersCustom
}).Model(&user{}).First(&userCustom)

[iTanken]

At least ID field and foreignKey tag are required.

type User struct {
	gorm.Model
	Username string
-	Orders   []Order
+	Orders   []Order `gorm:"foreignKey:UserID;references:ID"`
}

type CustomUserRes struct {
+	ID       uint                            `gorm:"primaryKey"`
	Username string                          // <--- No gorm default fields required
-	Orders   []Order
+	Orders   []Order `gorm:"foreignKey:UserID;references:ID"`
}

var user User
var userCustom CustomUserRes
var ordersCustom CustomOrderRes

db.Preload("Orders", func (tx *gorm.DB) *gorm.DB {
-  return tx.Scan(&ordersCustom) // <--- I want to fit the preload result to ordersCustom
+  return tx.Model(&Order{}).Scan(&ordersCustom) // <--- I want to fit the preload result to ordersCustom
}).Model(&user).First(&userCustom)