生成XML视图时CakePHP 3出错；第6列第1行出现错误XML声明仅允许在文档开头出现；

在使用CakePHP 3生成XML输出时，我花了几个小时试图解决以下问题。我试图用JSON和XML公开数据JSON视图在我使用时非常有效：/bookmarker/bookmarks.JSON但是。。。当我尝试使用此URL:/bookmarker/bookmarks.xml时，我得到以下响应：

此页面包含以下错误：

第6列第1行出错：仅在文档开头允许XML声明 下面是第一个错误之前的页面呈现

视图源如下所示：

有人说，这个错误是因为任何PHP文件末尾有一个空行。我很确定我在以下内容中没有任何空行：AppController.php、routes.php和BookmarksController.php

Router::scope('/', function ($routes) {
    // Connect the default routes.
    $routes->fallbacks('InflectedRoute');

    // This allows us to have a RESTful Route for BookmarksController
    $routes->extensions(['json', 'xml']);
    $routes->resources('Bookmarks');
    $routes->resources('Tags');
});

public function index()
    {
        $this->paginate = [
            'contain' => ['Users'],
            'conditions' => [
                'Bookmarks.user_id' => $this->Auth->user('id'),
            ]
        ];
        $this->set('bookmarks', $this->paginate($this->Bookmarks));
        $this->set('_serialize', ['bookmarks']);
    }

public function initialize()
    {
        parent::initialize();
        $this->loadComponent('Flash');

        // Component to enable REST responses
        $this->loadComponent('RequestHandler');

        $this->loadComponent('Auth', [
            'authorize' => 'Controller', // We will be creating a custom autorization method (see isAuthorized() bellow)
            'authenticate' => [
                'Form' => [
                    'fields' => [
                        'username' => 'email',
                        'password' => 'password'
                    ]
                ]
            ],
            'loginAction' => [
                'controller' => 'Users',
                'action' => 'login'
            ],
            'unauthorizedRedirect' => $this->referer()
        ]);

        // Allow the display action so our pages controller
        // continues to work.
        $this->Auth->allow(['display']);
    }

这是我的配置： 1） Myroutes.php

Router::scope('/', function ($routes) {
    // Connect the default routes.
    $routes->fallbacks('InflectedRoute');

    // This allows us to have a RESTful Route for BookmarksController
    $routes->extensions(['json', 'xml']);
    $routes->resources('Bookmarks');
    $routes->resources('Tags');
});

public function index()
    {
        $this->paginate = [
            'contain' => ['Users'],
            'conditions' => [
                'Bookmarks.user_id' => $this->Auth->user('id'),
            ]
        ];
        $this->set('bookmarks', $this->paginate($this->Bookmarks));
        $this->set('_serialize', ['bookmarks']);
    }

public function initialize()
    {
        parent::initialize();
        $this->loadComponent('Flash');

        // Component to enable REST responses
        $this->loadComponent('RequestHandler');

        $this->loadComponent('Auth', [
            'authorize' => 'Controller', // We will be creating a custom autorization method (see isAuthorized() bellow)
            'authenticate' => [
                'Form' => [
                    'fields' => [
                        'username' => 'email',
                        'password' => 'password'
                    ]
                ]
            ],
            'loginAction' => [
                'controller' => 'Users',
                'action' => 'login'
            ],
            'unauthorizedRedirect' => $this->referer()
        ]);

        // Allow the display action so our pages controller
        // continues to work.
        $this->Auth->allow(['display']);
    }

2） MyBookmarksController.php

Router::scope('/', function ($routes) {
    // Connect the default routes.
    $routes->fallbacks('InflectedRoute');

    // This allows us to have a RESTful Route for BookmarksController
    $routes->extensions(['json', 'xml']);
    $routes->resources('Bookmarks');
    $routes->resources('Tags');
});

public function index()
    {
        $this->paginate = [
            'contain' => ['Users'],
            'conditions' => [
                'Bookmarks.user_id' => $this->Auth->user('id'),
            ]
        ];
        $this->set('bookmarks', $this->paginate($this->Bookmarks));
        $this->set('_serialize', ['bookmarks']);
    }

public function initialize()
    {
        parent::initialize();
        $this->loadComponent('Flash');

        // Component to enable REST responses
        $this->loadComponent('RequestHandler');

        $this->loadComponent('Auth', [
            'authorize' => 'Controller', // We will be creating a custom autorization method (see isAuthorized() bellow)
            'authenticate' => [
                'Form' => [
                    'fields' => [
                        'username' => 'email',
                        'password' => 'password'
                    ]
                ]
            ],
            'loginAction' => [
                'controller' => 'Users',
                'action' => 'login'
            ],
            'unauthorizedRedirect' => $this->referer()
        ]);

        // Allow the display action so our pages controller
        // continues to work.
        $this->Auth->allow(['display']);
    }

3） 在我的AppController.php中

Router::scope('/', function ($routes) {
    // Connect the default routes.
    $routes->fallbacks('InflectedRoute');

    // This allows us to have a RESTful Route for BookmarksController
    $routes->extensions(['json', 'xml']);
    $routes->resources('Bookmarks');
    $routes->resources('Tags');
});

public function index()
    {
        $this->paginate = [
            'contain' => ['Users'],
            'conditions' => [
                'Bookmarks.user_id' => $this->Auth->user('id'),
            ]
        ];
        $this->set('bookmarks', $this->paginate($this->Bookmarks));
        $this->set('_serialize', ['bookmarks']);
    }

public function initialize()
    {
        parent::initialize();
        $this->loadComponent('Flash');

        // Component to enable REST responses
        $this->loadComponent('RequestHandler');

        $this->loadComponent('Auth', [
            'authorize' => 'Controller', // We will be creating a custom autorization method (see isAuthorized() bellow)
            'authenticate' => [
                'Form' => [
                    'fields' => [
                        'username' => 'email',
                        'password' => 'password'
                    ]
                ]
            ],
            'loginAction' => [
                'controller' => 'Users',
                'action' => 'login'
            ],
            'unauthorizedRedirect' => $this->referer()
        ]);

        // Allow the display action so our pages controller
        // continues to work.
        $this->Auth->allow(['display']);
    }

---

如果输出中有空格：您是否还检查了XML输出的视图文件/模板（XML默认布局和索引函数的XML视图）？您好@user1843159谢谢您的回复，我只是删除了这些文件末尾的行：*/vendor/cakephp/cakephp/src/View/View.php****/vendor/cakephp/cakephp/src/View/XmlView.php**没有更改。我仍然有错误。哦，对不起，请不要在供应商中编辑核心文件。如果需要使用核心文件的修改版本，可以在/src/Template/Layout/xml/default.ctp和/src/Template/Bookmarks/xml/index.ctp中创建自己的视图模板问题中发布的代码与您描述的错误模式无关。不管是谁告诉你的，请把所给出的信息当作暗示，而不是你的问题的解决方案或实际原因。错误模式显示，在输出XML文档之前，您向浏览器输出了6个看起来像空白的字符。然后需要找到导致第一次输出的代码。如果手边没有代码库（只需在这里提问），几乎不可能向大家打招呼，谢谢大家的评论和帮助。我终于找到了这个问题的根源；如@AD7six所述，它位于配置文件中。如果输出中有空格：您是否也检查了XML输出的视图文件/模板（XML默认布局和索引函数的XML视图）？您好@user1843159谢谢您的回复，我只是删除了这些文件末尾的行：*/vendor/cakephp/cakephp/src/View/View.php****/vendor/cakephp/cakephp/src/View/XmlView.php**没有更改。我仍然有错误。哦，对不起，请不要在供应商中编辑核心文件。如果需要使用核心文件的修改版本，可以在/src/Template/Layout/xml/default.ctp和/src/Template/Bookmarks/xml/index.ctp中创建自己的视图模板问题中发布的代码与您描述的错误模式无关。不管是谁告诉你的，请把所给出的信息当作暗示，而不是你的问题的解决方案或实际原因。错误模式显示，在输出XML文档之前，您向浏览器输出了6个看起来像空白的字符。然后需要找到导致第一次输出的代码。如果手边没有代码库（只需在这里提问），几乎不可能向大家打招呼，谢谢大家的评论和帮助。我终于找到了这个问题的根源；它位于一个配置文件中，如@AD7six所述。