database.go

func (u *User) Follow(db *gorm.DB, user User) {
	if !u.IsFollowing(db, user) {
		db.Model(&u).Association("Followers").Append(&user)
	}
}

func (u *User) Unfollow(db *gorm.DB, user User) {
	if u.IsFollowing(db, user) {
		db.Model(&u).Association("Followers").Delete(&user)
	}
}

func (u *User) IsFollowing(db *gorm.DB, user User) bool {
	return db.Model(&u).Association("Followers").Find(user).Count() > 0
}