laravel - 如何使用 Laravel API 资源对加载的关系进行分页

Question

我需要在它的资源中加载模型关系并对它们进行分页。
就我而言，我有 Category和 Path型号，加上 CategoryResource和 PathResourcetoArray CategoryResource的方法如下所示:

public function toArray($request)
{
    return [
        'id'   => $this->id,
        'name' => $this->name,
        'slug' => $this->slug,
        'order' => $this->order,
        'paths' => PathResource::collection($this->whenLoaded('paths'))
    ];
}

和 toArray PathResource的方法如下所示:

public function toArray($request)
{
    return parent::toArray($request);
}

问题 是如何加载和分页相关的 Path在我的 CategoryResource ?

Answer 1

我遇到了同样的问题并以这种方式解决了它:
先决条件
您必须为 Path 拥有/创建资源模型即 PathResource创建一个使用这个命令:php artisan make:resource PathResource 解决方案
解决方法是使用laravel paginate关于关系和使用 transform分页集合上的方法将其项目转换为您的资源。
第一步
使用以下命令创建用于对应用程序中的任何资源进行分页的基类:php artisan make:resource PaginatedCollection -c编辑 PaginatedCollection并添加以下代码:

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\ResourceCollection;

class PaginatedCollection extends ResourceCollection
{

    /**
     * An array to store pagination data that comes from paginate() method.
     * @var array
     */
    protected $pagination;

    /**
     * PaginatedCollection constructor.
     *
     * @param mixed $resource paginated resource using paginate method on models or relations.
     */
    public function __construct($resource)
    {

        $this->pagination = [
            'total' => $resource->total(), // all models count
            'count' => $resource->count(), // paginated result count
            'per_page' => $resource->perPage(),
            'current_page' => $resource->currentPage(),
            'total_pages' => $resource->lastPage()
        ];

        $resource = $resource->getCollection();

        parent::__construct($resource);
    }

    /**
     * Transform the resource collection into an array.
     * now we have data and pagination info.
     *
     * @param \Illuminate\Http\Request $request
     * @return array
     */
    public function toArray($request)
    {
        return [
            // our resources
            'data' => $this->collection,

            // pagination data
            'pagination' => $this->pagination
        ];
    }
}

第二步
为您的模型制作集合资源并扩展 PaginatedCollection而不是默认 ResourceCollection .
运行此命令以执行此操作: php artisan make:resource PathCollection -c现在编辑您的新集合类 PathCollection并覆盖 toArray方法:

/**
 * Transform the resource collection into an array.
 *
 * In this method use your already created resources
 * to avoid code duplications
 *
 * @param \Illuminate\Http\Request $request
 * @return array
 */
public function toArray($request)
{
    return [

        // Here we transform any item in paginated items to a resource

        'data' => $this->collection->transform(function ($path) {
            return new PathResource($path);
        }),

        'pagination' => $this->pagination,
    ];
}

最后一步
在您的 CategoryResource使用 PathCollection像这样:

return [
    'id'   => $this->id,
    'name' => $this->name,
    'slug' => $this->slug,
    'order' => $this->order,
    'paths' => new PathCollection(
        new LengthAwarePaginator(
            $this->whenLoaded('paths'),
            $this->paths_count,
            10
        )
    ),
];

并确保您导入 LengthAwarePaginator类(class): use Illuminate\Pagination\LengthAwarePaginator; 用法

$category = Category::with('paths')->withCount('paths')->find(1);
return new CategoryResource($category);