Mutators

Introduction

Accessors and mutators allow you to format Eloquent attribute values when you retrieve or set them on model instances. For example, you may want to get user information from database and response it to the browser, but you don’t want users’ password field exposed out.

Accessors & Mutators

Defining An Accessor

To define an accessor, create a GetFooAttribute method on your model where Foo is the “camel” cased name of the field in the model you wish to access. In this example, we’ll define an accessor for the Password attribute. The accessor will automatically be called by Eloquent when attempting to retrieve the value of the Password attribute:

type User struct {
	ID        *uint      `gorm:"column:user_id;primary_key;auto_increment"`
	Name      *string    `gorm:"column:user_name;type:varchar(100)"`
	Email     *string    `gorm:"column:user_email;type:varchar(100);unique_index;not null"`
	Password  *string    `gorm:"column:user_password;type:varchar(100);not null"`
	CreatedAt *zone.Time `gorm:"column:user_created_at"`
	UpdatedAt zone.Time  `gorm:"column:user_updated_at"`
	DeletedAt *zone.Time `gorm:"column:user_deleted_at"`
	model.BaseModel
}
// Mutator: auto hidden password
func (user *User) GetPasswordAttribute(value interface{}) interface{} {
	return ptr.String("xxx")
}

As you can see, the original value of the column is passed to the accessor, allowing you to manipulate and return the value. To access the value of the accessor, you may access the Password attribute on a model instance:

newUser := User{
    ID: ptr.Uint(userId),
}
if err := m.H().First(&newUser, false); err != nil {
    return err
}
password := newUser.Password

And the password variable’s value would be xxx.

Defining A Mutator

To define a mutator, create a SetFooAttribute method on your model where Foo is the “camel” cased name of the field in the model you wish to access. In this example, we’ll define a mutator for the Name attribute. The mutator will automatically be called by Eloquent when attempting to update the value of the Name attribute in database:

type User struct {
	ID        *uint      `gorm:"column:user_id;primary_key;auto_increment"`
	Name      *string    `gorm:"column:user_name;type:varchar(100)"`
	Email     *string    `gorm:"column:user_email;type:varchar(100);unique_index;not null"`
	Password  *string    `gorm:"column:user_password;type:varchar(100);not null"`
	CreatedAt *zone.Time `gorm:"column:user_created_at"`
	UpdatedAt zone.Time  `gorm:"column:user_updated_at"`
	DeletedAt *zone.Time `gorm:"column:user_deleted_at"`
	model.BaseModel
}
// Mutator: auto generate user name
func (user *User) SetNameAttribute(value interface{}) {
	user.Name = ptr.String(hash.Md5(*user.Email))
}

As you can see, the original value of Name is passed to the mutator, and the mutator set the user.Name to user.Email’s MD5 as the random Name, and then update the Name field as defined in the database.