filter_var($request->input('login'), FILTER_VALIDATE_EMAIL) ? 'email' : 'name'

public function login(Requests $request) {
 //假设字段是 email
 if ($this->guard()->attempt($request->only('email', 'password'))) {
  return $this->sendLoginResponse($request);
 }

 //假设字段是 mobile
 if ($this->guard()->attempt($request->only('mobile', 'password'))) {
  return $this->sendLoginResponse($request);
 }

 //假设字段是 username
 if ($this->guard()->attempt($request->only('username', 'password'))) {
  return $this->sendLoginResponse($request);
 }

 return $this->sendFailedLoginResponse($request);
}

public function retrieveByCredentials(array $credentials)
{
 if (empty($credentials)) {
  return;
 }

 // First we will add each credential element to the query as a where clause.
 // Then we can execute the query and, if we found a user, return it in a
 // Eloquent User "model" that will be utilized by the Guard instances.
 $query = $this->createModel()->newQuery();

 foreach ($credentials as $key => $value) {
  if (! Str::contains($key, 'password')) {
   $query->orWhere($key, $value);
  }
 }

 return $query->first();
}

class AuthServiceProvider extends ServiceProvider
{
 /**
  * 注册任何应用认证／授权服务。
  *
  * @return void
  */
 public function boot()
 {
  $this->registerPolicies();

  Auth::provider('custom', function ($app, array $config) {
   // 返回 Illuminate\Contracts\Auth\UserProvider 实例...

   return new CustomUserProvider(new BcryptHasher(), config('auth.providers.custom.model'));
  });
 }
}

'providers' => [
 'users' => [
  'driver' => 'eloquent',
  'model' => App\Models\User::class,
 ],

  'custom' => [
   'driver' => 'custom',
   'model' => App\Models\User::class,
  ],
],

'guards' => [
 'web' => [
  'driver' => 'session',
  'provider' => 'custom',
 ],

 'api' => [
  'driver' => 'passport',
  'provider' => 'users',
 ],
],