Laravel检查电子邮件和提供者是否存在

Question

我正在使用laravel，我想进行身份验证注册，并通过电子邮件和提供商进行检查。使用电子邮件和提供商，因为如果用户使用社交媒体（例如：facebook）登录时具有与用户使用电子邮件登录相同的电子邮件，则用户可以注册。我只能通过电子邮件进行检查。 这是我的注册控制器

<?php

namespace App\Http\Controllers\Auth;

use App\User;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Validator;
use Illuminate\Foundation\Auth\RegistersUsers;

class RegisterController extends Controller
{

    public function __construct()
    {
        $this->middleware('guest');
    }


    protected function validator(array $data)
    {
        return Validator::make($data, [
            'name' => 'required|string|max:255',
            'username' => 'required|max:255',
            'email' => 'required|string|email|max:255|unique:users',
            'password' => 'required|string|min:6|confirmed',
            'provider' => 'unique:users',

        ]);
    }

    /**
     * Create a new user instance after a valid registration.
     *
     * @param  array  $data
     * @return \App\User
     */

    protected function create(array $data)
    {
        // $prov = 'Email';

        return User::create([
            'name' => $data['name'],
            'username' => $data['username'],
            'email' => $data['email'],
            'password' => Hash::make($data['password']),
            'provider' => 'Email',
        ]);
    }
}