Laravel：CRUD 路由有一个空参数

Question

我的 CRUD 路由有问题。在我的控制器 UserGroupsController 中编辑的方法中，参数 $userGroup 为空。

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用户组控制器

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class UserGroupsController extends Controller\n{\n    public function edit(UserGroup $userGroup)\n      {        \n        if (Auth::check())\n        {\n          $users = User::pluck(\'name\',\'id\')->all();\n          $groups = Group::pluck(\'name\',\'id\')->all();\n          return view(\'users-group.edit\', compact(\'userGroup\',\'users\',\'groups\'));\n        }else{\n          return redirect(\'login\');\n        }\n\n    }\n}\n

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编辑.blade.php

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<div class="panel panel-default">\n <div class="panel-heading">Edit</div>\n     <div class="panel-body">\n          {{ $userGroup }}\n          {!! Form::model($userGroup,[\'method\' => \'PATCH\', \'route\' => [\'users-group.update\', $userGroup->id], \'id\' => \'user_group-form\', \'class\' => \'form-horizontal\'] ) !!}\n          {{ csrf_field() }}\n\n          <input type=\'hidden\' name=\'id\' value=\'{!! $userGroup->id !!}\'>\n          @include(\'users-group.form\',array(\'submitButton\' => \'Edit User Group\'))              \n       {!! Form::close()  !!}\n</div>\n

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表单.blade.php

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<div class="form-group">\n  <label for="user_id" class="col-md-4 control-label">User</label>\n  <div class="col-md-6">\n    {!! form::select(\'user_id\', $users, $userGroup->user_id,[\'class\' => \'form-control\']) !!}\n  </div>\n</div>\n<div class="form-group">\n  <label for="group_id" class="col-md-4 control-label">Group</label>\n  <div class="col-md-6">\n    {!! form::select(\'group_id\', $groups, $userGroup->group_id,[\'class\' => \'form-control\']) !!}\n  </div>\n</div>\n<div class="form-group">\n    <div class="col-md-6 col-md-offset-4">\n        {!! Form::submit($submitButton) !!}\n    </div>\n</div>\n

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路线：

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Route::group([\'middleware\'=>[\'web\']], function ()\n{\n  Route::resource(\'users\',\'UsersController\');\n  Route::resource(\'users-group\',\'UserGroupsController\');\n  Route::resource(\'companies\',\'CompaniesController\');\n});\n

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php artisan 路线：列表：

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|        | POST      | users-group                    | users-group.store   | App\\Http\\Controllers\\UserGroupsController@store                        | web          |\n|        | GET|HEAD  | users-group/create             | users-group.create  | App\\Http\\Controllers\\UserGroupsController@create                       | web          |\n|        | PUT|PATCH | users-group/{users_group}      | users-group.update  | App\\Http\\Controllers\\UserGroupsController@update                       | web          |\n|        | DELETE    | users-group/{users_group}      | users-group.destroy | App\\Http\\Controllers\\UserGroupsController@destroy                      | web          |\n|        | GET|HEAD  | users-group/{users_group}      | users-group.show    | App\\Http\\Controllers\\UserGroupsController@show                         | web          |\n|        | GET|HEAD  | users-group/{users_group}/edit | users-group.edit    | App\\Http\\Controllers\\UserGroupsController@edit\n

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dd($用户组):

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UserGroup {#199 \xe2\x96\xbc\n  #fillable: array:2 [\xe2\x96\xbc\n    0 => "user_id"\n    1 => "group_id"\n  ]\n  #connection: null\n  #table: null\n  #primaryKey: "id"\n  #keyType: "int"\n  #perPage: 15\n  +incrementing: true\n  +timestamps: true\n  #attributes: []\n  #original: []\n  #relations: []\n  #hidden: []\n  #visible: []\n  #appends: []\n  #guarded: array:1 [\xe2\x96\xb6]\n  #dates: []\n  #dateFormat: null\n  #casts: []\n  #touches: []\n  #observables: []\n  #with: []\n  +exists: false\n  +wasRecentlyCreated: false\n}\n

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在文件 edit.blade.php 中，我打印变量 $userGroup，但返回“[ ]”。我对 UsersControllers 有相同的代码，但是可以工作。

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当我提交表单时，我收到以下错误：

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MethodNotAllowedHttpException in RouteCollection.php\n

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对不起，英语，我希望你能理解我的问题，我可以提供更多信息。谢谢

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Answer 1

这是您的代码中的问题。从输出中可以清楚地看出php artisan route:list，UserGroupsController 中的编辑函数所期望的参数名称是$users_group而不是$userGroup。所以我建议你两个简单的解决方案。

解决方案#1 像这样更改 UserGroupsController 的编辑功能。

class UserGroupsController extends Controller
{
    public function edit(UserGroup $user_group)
      {        
        if (Auth::check())
        {
          $users = User::pluck('name','id')->all();
          $groups = Group::pluck('name','id')->all();
          return view('users-group.edit', compact('userGroup','users','groups'));
        }else{
          return redirect('login');
        }

    }
}

或者

解决方案#2 更改您的路由函数，以便php artisan route:list输出此内容。

|        | POST      | users-group                    | users-group.store   | App\Http\Controllers\UserGroupsController@store                        | web          |
|        | GET|HEAD  | users-group/create             | users-group.create  | App\Http\Controllers\UserGroupsController@create                       | web          |
|        | PUT|PATCH | users-group/{userGroup}      | users-group.update  | App\Http\Controllers\UserGroupsController@update                       | web          |
|        | DELETE    | users-group/{userGroup}      | users-group.destroy | App\Http\Controllers\UserGroupsController@destroy                      | web          |
|        | GET|HEAD  | users-group/{userGroup}      | users-group.show    | App\Http\Controllers\UserGroupsController@show                         | web          |
|        | GET|HEAD  | users-group/{userGroup}/edit | users-group.edit    | App\Http\Controllers\UserGroupsController@edit

备注users_group必须改为userGroup.

好吧，它有效，但为什么呢？

这是因为Laravel 的隐式路由绑定。Laravel 自动解析路由或控制器操作中定义的 Eloquent 模型，其类型提示变量名称与路由段名称匹配。例如：

Route::get('api/users/{user}', function (App\User $user) {
    return $user->email;
});

由于$user变量被类型提示为App\UserEloquent 模型，并且变量名称与{user}URI 段匹配，Laravel 将自动注入 ID 与请求 URI 中相应值匹配的模型实例。如果变量名称与 {user} URI 段不匹配，Laravel 将不会注入任何模型实例，因此该变量将保留为空。