use Validator;

class CommentController
{

public function postStoreComment(Request $request)
{
$validator = Validator::make($request->all(),[
'comment' => 'required',// 只是实例，就写个简单的规则，你的网站要是这么写欢迎在评论里贴网址
]);

if ($validator->fails()) {
  return redirect()
    ->back()
    ->withErrors($validator)
    ->withInput();
}

}

namespace App\Http\Requests;

use App\Http\Requests\Request; // 可以看到，这个基类是在我们的项目中的，这意味着我们可以修改它

class StoreCommentRequest extends Request
{
/**

• Determine if the user is authorized to make this request.
• @return bool
  */
  public function authorize() // 这个方法可以用来控制访问权限，例如禁止未付费用户评论…
  {
  return false; // 注意！这里默认是false，记得改成true
  }

/**

• Get the validation rules that apply to the request.
• @return array
  */
  public function rules() // 这个方法返回验证规则数组，也就是Validator的验证规则
  {
  return [
  //
  ];
  }
  }

// ...

public function rules()
{
return [

];

}

// ...

// ...

// 之前：public function postStoreComment(Request $request)
public function postStoreComment(\App\Http\Requests\StoreCommentRequest $request)
{
// ...
}

// ...

use Illuminate\Support\ServiceProvider;
use Illuminate\Contracts\Validation\ValidatesWhenResolved;

class ValidationServiceProvider extends ServiceProvider
{
/**

• Register the service provider.
• @return void
  */
  public function register()
  {
  $this->registerValidationResolverHook(); // 看我看我看我

$this->registerPresenceVerifier();

$this->registerValidationFactory();

}

/**

• Register the "ValidatesWhenResolved" container hook.
• @return void
  */
  protected function registerValidationResolverHook() // 对，就是我
  {
  // 这里可以看到对ValidatesWhenResolved的实现做了一个监听
  $this->app->afterResolving(function (ValidatesWhenResolved $resolved) {
  $resolved->validate(); // 然后调用了它的validate方法进行验证
  });
  }

// ...

namespace Illuminate\Foundation\Http;

use Illuminate\Http\Request;
use Illuminate\Http\Response;
use Illuminate\Http\JsonResponse;
use Illuminate\Routing\Redirector;
use Illuminate\Container\Container;
use Illuminate\Contracts\Validation\Validator;
use Illuminate\Http\Exception\HttpResponseException;
use Illuminate\Validation\ValidatesWhenResolvedTrait;
use Illuminate\Contracts\Validation\ValidatesWhenResolved; // 是你
use Illuminate\Contracts\Validation\Factory as ValidationFactory;

// 我们app\Http\Requests\Request便是继承于这个FormRequest类
class FormRequest extends Request implements ValidatesWhenResolved // 就是你
{
use ValidatesWhenResolvedTrait; // 这个我们待会儿也要看看

// ...

use Illuminate\Contracts\Validation\ValidationException;
use Illuminate\Contracts\Validation\UnauthorizedException;

/**

• Provides default implementation of ValidatesWhenResolved contract.
  */
  trait ValidatesWhenResolvedTrait
  {
  /**

  • Validate the class instance.
  • @return void
    */
    public function validate() // 这里实现了validate方法
    {
    $instance = $this->getValidatorInstance(); // 这里获取了Validator实例

  if (! $this->passesAuthorization()) {
  $this->FailedAuthorization(); // 这是调用了访问授权的失败处理
  } elseif (! $instance->passes()) {
  $this->FailedValidation($instance); // 这里调用了验证失败的处理，我们主要看这里
  }
  }

// ...

/**

• Handle a failed validation attempt.
• @param \Illuminate\Contracts\Validation\Validator $validator
• @return mixed
  */
  protected function failedValidation(Validator $validator)
  {
  throw new HttpResponseException($this->response( // 这里抛出了传说中的异常
  $this->formatErrors($validator)
  ));
  }

/**

• Run the route action and return the response.
• @param \Illuminate\Http\Request $request
• @return mixed
  */
  public function run(Request $request)
  {
  $this->container = $this->container ?: new Container;

try {
  if (! is_string($this->action['uses'])) {
    return $this->runCallable($request);
  }

  if ($this->customDispatcherIsBound()) {
    return $this->runWithCustomDispatcher($request);
  }

  return $this->runController($request);
} catch (HttpResponseException $e) { // 就是这里
  return $e->getResponse(); // 这里直接返回了Response给客户端
}

}

// ...

// 132行：
if ($this->ajax() || $this->wantsJson()) { // 对AJAX请求的处理
return new JsonResponse($errors,422);
}

return $this->redirector->to($this->getRedirectUrl()) // 对普通表单提交的处理
->withInput($this->except($this->dontFlash))
->withErrors($errors,$this->errorBag);

// ...