i want each email to be unique for a certain field's id . how is it possible for validation in laravel 5

laravel 5

In laravel 5 form validation i need email to be only unique for a certain field's id in the db table .

$this->validate($request,[
        'name'=>'required',
        'email' => 'unique:users,email,',
        'password'=>'required',
        ]);

via Chebli Mohamed