PHP應用
<?php
// ... 
use Validator;
class CommentController
{
  public function postStoreComment(Request $request)
  {
    $validator = Validator::make($request->all(), [
      'comment' => 'required', // 只是實例,就寫個簡單的規則,你的網站要是這么寫歡迎在評論里貼網址
    ]);
    if ($validator->fails()) {
      return redirect()
        ->back()
        ->withErrors($validator)
        ->withInput();
    }
  }

PHP應用
<?php
namespace App\Http\Requests;
use App\Http\Requests\Request; // 可以看到,這個基類是在我們的項目中的,這意味著我們可以修改它
class StoreCommentRequest extends Request
{
  /**
   * Determine if the user is authorized to make this request.
   *
   * @return bool
   */
  public function authorize() // 這個方法可以用來控制訪問權限,例如禁止未付費用戶評論…
  {
    return false; // 注意!這里默認是false,記得改成true
  }
  /**
   * Get the validation rules that apply to the request.
   *
   * @return array
   */
  public function rules() // 這個方法返回驗證規則數組,也就是Validator的驗證規則
  {
    return [
      //
    ];
  }
}

PHP應用
<?php
// ...
  public function rules()
  {
    return [
    ];
  }
// ...

PHP應用
<?php
// ...
  // 之前：public function postStoreComment(Request $request)
  public function postStoreComment(\App\Http\Requests\StoreCommentRequest $request)
  {
    // ...
  }
// ...

PHP應用
<?php
namespace Illuminate\Validation;
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() // 對,就是我
  {
    // 這里可以看到對`ValidatesWhenResolved`的實現做了一個監聽
    $this->app->afterResolving(function (ValidatesWhenResolved $resolved) {
      $resolved->validate(); // 然后調用了它的`validate`方法進行驗證
    });
  }
// ...

PHP應用
<?php 
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;
// 我們`app\Http\Requests\Request`便是繼承于這個`FormRequest`類
class FormRequest extends Request implements ValidatesWhenResolved // 就是你
{
  use ValidatesWhenResolvedTrait; // 這個我們待會兒也要看看
  // ...

PHP應用
<?php
namespace Illuminate\Validation;
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() // 這里實現了`validate`方法
  {
    $instance = $this->getValidatorInstance(); // 這里獲取了`Validator`實例
    if (! $this->passesAuthorization()) {
      $this->failedAuthorization(); // 這是調用了訪問授權的失敗處理
    } elseif (! $instance->passes()) {
      $this->failedValidation($instance); // 這里調用了驗證失敗的處理,我們主要看這里
    }
  }
  // ...

PHP應用
<?php
// ...
  /**
   * Handle a failed validation attempt.
   *
   * @param \Illuminate\Contracts\Validation\Validator $validator
   * @return mixed
   */
  protected function failedValidation(Validator $validator)
  {
    throw new HttpResponseException($this->response( // 這里拋出了傳說中的異常
      $this->formatErrors($validator)
    ));
  }

PHP應用
<?php
  // ...
  /**
   * 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) { // 就是這里
      return $e->getResponse(); // 這里直接返回了Response給客戶端
    }
  }
  // ...

PHP應用
<?php
// ...
  // 132行：
  if ($this->ajax() || $this->wantsJson()) { // 對AJAX請求的處理
    return new JsonResponse($errors, 422);
  }
  return $this->redirector->to($this->getRedirectUrl()) // 對普通表單提交的處理
                  ->withInput($this->except($this->dontFlash))
                  ->withErrors($errors, $this->errorBag);
// ...