Gorm Preload

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type User struct {
	ID     uint 
	UserID uint
	RoleID uint
	DeletedAt gorm.DeletedAt
	// any other field
    // code1
	Roles []Role `gorm:"->"`
	// code2
	UserRoles []UserRole `gorm:"->"`
}

type UserRole struct {
	ID     uint 
	UserID uint
	RoleID uint
	DeletedAt gorm.DeletedAt
	Role *Role
}

type Role struct {
	ID     uint 
	// any other field
}

func query() {
	var users []User
	// 这种情况下 无法对UserRole表进行软删除判断
	db.Model(User{}).Preload("Roles").Find(&users)
	
	// 解决方案1. 不使用软删除
	
	// 解决方案2. 两步Preload 不直接关联Role 实现如下
    // db.Model(User{}).Preload("UserRoles.Role").Find(&users)
}

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type User struct {
	ID        uint
	UserID    uint
	RoleID    uint
	DeletedAt gorm.DeletedAt
	// any other field
	Roles []Role `gorm:"->"`
}

type UserRole struct {
	ID        uint
	UserID    uint
	RoleID    uint
}

type Role struct {
	ID uint
	// any other field
}

func query() {
	var users []User
	db.Model(User{}).Preload("Roles").Find(&users)
}

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type User struct {
	ID        uint
	UserID    uint
	RoleID    uint
	DeletedAt gorm.DeletedAt
	// any other field
	// code2
	UserRoles []UserRole `gorm:"->"`
}

type UserRole struct {
	ID        uint
	UserID    uint
	RoleID    uint
	DeletedAt gorm.DeletedAt
	Role      *Role
}

type Role struct {
	ID uint
	// any other field
}

func query() {
	var users []User
	db.Model(User{}).Preload("UserRoles.Role").Find(&users)
}