向 eloquent 资源添加过滤器以有条件地附加关系

Question

Laravel 5.8 PHP 7.4

我想像这样有条件地加载关系

http://127.0.0.1:8000/api/posts 

和

http://127.0.0.1:8000/api/posts/1 are my end points now, I want to load comments like

http://127.0.0.1:8000/api/posts/?include=comments 和

http://127.0.0.1:8000/api/posts/1/?include=comments

如果查询参数存在，那么它应该加载带有帖子的 cmets，或者它应该只加载帖子/帖子

我通过引用 blog post 来做到这一点

现在，RequestQueryFilter

<?php
namespace App\Http\Resources;
use Illuminate\Http\Request;
class RequestQueryFilter
{
    public function attach($resource, Request $request = null)
    {
        $request = $request ?? request();
        return tap($resource, function($resource) use($request) {
            $this->getRequestIncludes($request)->each(function($include) use($resource) {
                $resource->load($include);
            });
        });
    }
    protected function getRequestIncludes(Request $request)
    {
        // return collect(data_get($request->input(), 'include', [])); //single relationship
        return collect(array_map('trim', explode(',', data_get($request->input(), 'include', [])))); //multiple relationships
    }
}

在助手中

<?php
if ( ! function_exists('filter') ) {
    function filter($attach) 
    {
        return app('filter')->attach($attach);
    }
}
?>

在 PostController 中

public funciton show(Request $request, Post $post) {
    return new PostResource(filter($post));
}

但是当我试图检索时

http://127.0.0.1:8000/api/posts/1/?include=comments getting no comments, with no error in log

解决方法是 PostResource

 public function toArray($request)
    {
        // return parent::toArray($request);
        $data = [
            'id' => $this->id,
            'name' => $this->title,
            'body' => $this->content,
        ];

        $filter = $request->query->get('include', '');

        if($filter){
          $data[$filter] = $this->resource->$filter;
        }

        return $data;
    }

Answer 1

我会使用

为帖子创建自定义资源

php artisan make_resource 

命令。 例如。发布资源。 资源的 toArray 函数必须返回数据。

PostResource.php

public function toArray($request){
     $data =['title' => $this->resource->title,

    'body' => $this->resource->body,

    'images' => new ImageCollection($this->whenLoaded('images')),
            ];

     $filter = $request->query->get('filter', '');

     if($filter){
      $data['comments'] => new CommentCollection($this->resource->comments);

     }
  return $data;
}

另外，对于集合，您需要创建一个 ResourceCollection。

PostResourceCollection.php

class PostResourceCollection extends ResourceCollection
{
    /**
     * Transform the resource into an array.
     *
     * @param  \Illuminate\Http\Request
     * @return array
     */
    public function toArray($request)
    {
        return [
            'data' => $this->collection,
        ];
    }
}

在您的控制器中： PostsController.php

   //show one post
     public function show(Post $post, Request $request)
        {

           /**this response is for API or vue.js if you need to generate view, pass the resource to the view */
            return $this->response->json( new PostResource($post));
        } 
    //list of posts
        public function index(Request $request)
            {
               $posts = Post::all();
               /**this response is for API or vue.js if you need to generate view, pass the resource to the view */
                return $this->response->json( new PostResourceCollection($posts));
            } 

Answer 2

我想像这样有条件地加载关系

使用load() 调用的延迟加载

Lazy Eager Loading 实现了与 Laravel 中的 with() 相同的最终结果，但不是自动的。 例如：

?include=comments

// Get all posts.
$posts = Post::without('comments')->all();

if (request('include') == 'comments')) {
    $posts->load('comments');
}

return PostResource::collection($posts);

或者，您可以要求 include 查询字符串是一个数组：

?include[]=comments&include[]=tags

// Validate the names against a set of allowed names beforehand, so there's no error.
$posts = Post::without(request('includes'))->all();

foreach (request('includes') as $include) {
    $posts->load($include);
}

return PostResource::collection($posts);

without() 仅在您将模型定义为自动预先加载您想要有条件加载的关系时才需要调用。

在 Controller 中过滤所有数据后，只需确保在 PostResource 中仅显示加载的关系

public function toArray($request) {
    $data = [...];

    foreach ($this->relations as $name => $relation)
    {
        $data[$name] = $relation;
    }

    return $data;
}

Answer 3

部分解决方案

需要对资源类做些小改动

public function toArray($request)
{
    // return parent::toArray($request);
    $data = [
        'id' => $this->id,
        'title' => $this->title,
        'body' => $this->body,
        'comments' => new CommentCollection($this->whenLoaded('comments')),
        'images' => new ImageCollection($this->whenLoaded('images')),
    ];
    return $data;
}

如果加载，它将加载 cmets 和图像，这取决于 include 查询参数，如果不包括，则不会加载关系。

然而，

在帖子收藏中

return [
    'data' => $this->collection->transform(function($post){
        return [
            'id' => $post->id,
            'title' => $post->title,
            'body' => $post->body,
            'comments' => new CommentCollection($post->whenLoaded('comments')),
            'images' => new ImageCollection($post->whenLoaded('images')),
        ];
    }),
];

将导致

“调用未定义的方法App\Models\Customer::whenLoaded()”，如果有人提出一个完整的解决方案，那将是一个很大的帮助，如果我能做到，我会在这里更新。