在自我中属于自己

I'm trying to establish a belongsTo relationship on the same table. But I'm unable to succeed. I didn't find any easily understandable examples on the Internet.

type Role struct {
    gorm.Model

    Name string
    Description string
    Inclusive bool

    Controller *Role `gorm:"foreignkey:controller;association_foreignkey:id"`
    SupervisedRoles []*Role `gorm:"foreignkey:Controller"`
    Permissions []*Permission
}

func (r *Role) GetController() (*Role, error) {
    controller := &Role{}
    return controller, db.DB.Model(r).Related(controller).Error
}

func (r *Role) GetSupervisedRoles() ([]*Role, error) {
    roles := []*Role{}

    return roles, db.DB.Model(r).Related(roles).Error
}

In my table, the "controller" field is a nullable foreign key that refers to another occurance of my "roles" table.

How do I implement it using GORM ?