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版本：5.6

Eloquent: API Resources

Introduction​

When building an API, you may need a transformation layer that sits between your Eloquent models and the JSON responses that are actually returned to your application's users. Laravel's resource classes allow you to expressively and easily transform your models and model collections into JSON.

Generating Resources​

To generate a resource class, you may use the make:resource Artisan command. By default, resources will be placed in the app/Http/Resources directory of your application. Resources extend the Illuminate\Http\Resources\Json\JsonResource class:

php artisan make:resource User

Resource Collections​

In addition to generating resources that transform individual models, you may generate resources that are responsible for transforming collections of models. This allows your response to include links and other meta information that is relevant to an entire collection of a given resource.

To create a resource collection, you should use the --collection flag when creating the resource. Or, including the word Collection in the resource name will indicate to Laravel that it should create a collection resource. Collection resources extend the Illuminate\Http\Resources\Json\ResourceCollection class:

php artisan make:resource Users --collection

php artisan make:resource UserCollection

Concept Overview​

提示

This is a high-level overview of resources and resource collections. You are highly encouraged to read the other sections of this documentation to gain a deeper understanding of the customization and power offered to you by resources.

Before diving into all of the options available to you when writing resources, let's first take a high-level look at how resources are used within Laravel. A resource class represents a single model that needs to be transformed into a JSON structure. For example, here is a simple User resource class:

<?php

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\JsonResource;

class User extends JsonResource
{
    /**
     * Transform the resource into an array.
     *
     * @param  \Illuminate\Http\Request
     * @return array
     */
    public function toArray($request)
    {
        return [
            'id' => $this->id,
            'name' => $this->name,
            'email' => $this->email,
            'created_at' => $this->created_at,
            'updated_at' => $this->updated_at,
        ];
    }
}

Every resource class defines a toArray method which returns the array of attributes that should be converted to JSON when sending the response. Notice that we can access model properties directly from the $this variable. This is because a resource class will automatically proxy property and method access down to the underlying model for convenient access. Once the resource is defined, it may be returned from a route or controller:

use App\User;
use App\Http\Resources\User as UserResource;

Route::get('/user', function () {
    return new UserResource(User::find(1));
});

Resource Collections​

If you are returning a collection of resources or a paginated response, you may use the collection method when creating the resource instance in your route or controller:

use App\User;
use App\Http\Resources\User as UserResource;

Route::get('/user', function () {
    return UserResource::collection(User::all());
});

Of course, this does not allow any addition of meta data that may need to be returned with the collection. If you would like to customize the resource collection response, you may create a dedicated resource to represent the collection:

php artisan make:resource UserCollection

Once the resource collection class has been generated, you may easily define any meta data that should be included with the response:

<?php

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\ResourceCollection;

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

After defining your resource collection, it may be returned from a route or controller:

use App\User;
use App\Http\Resources\UserCollection;

Route::get('/users', function () {
    return new UserCollection(User::all());
});

Writing Resources​

提示

If you have not read the concept overview, you are highly encouraged to do so before proceeding with this documentation.

In essence, resources are simple. They only need to transform a given model into an array. So, each resource contains a toArray method which translates your model's attributes into an API friendly array that can be returned to your users:

<?php

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\JsonResource;

class User extends JsonResource
{
    /**
     * Transform the resource into an array.
     *
     * @param  \Illuminate\Http\Request
     * @return array
     */
    public function toArray($request)
    {
        return [
            'id' => $this->id,
            'name' => $this->name,
            'email' => $this->email,
            'created_at' => $this->created_at,
            'updated_at' => $this->updated_at,
        ];
    }
}

Once a resource has been defined, it may be returned directly from a route or controller:

use App\User;
use App\Http\Resources\User as UserResource;

Route::get('/user', function () {
    return new UserResource(User::find(1));
});

Relationships​

If you would like to include related resources in your response, you may add them to the array returned by your toArray method. In this example, we will use the Post resource's collection method to add the user's blog posts to the resource response:

/**
 * Transform the resource into an array.
 *
 * @param  \Illuminate\Http\Request
 * @return array
 */
public function toArray($request)
{
    return [
        'id' => $this->id,
        'name' => $this->name,
        'email' => $this->email,
        'posts' => PostResource::collection($this->posts),
        'created_at' => $this->created_at,
        'updated_at' => $this->updated_at,
    ];
}
提示

If you would like to include relationships only when they have already been loaded, check out the documentation on conditional relationships.

Resource Collections​

While resources translate a single model into an array, resource collections translate a collection of models into an array. It is not absolutely necessary to define a resource collection class for each one of your model types since all resources provide a collection method to generate an "ad-hoc" resource collection on the fly:

use App\User;
use App\Http\Resources\User as UserResource;

Route::get('/user', function () {
    return UserResource::collection(User::all());
});

However, if you need to customize the meta data returned with the collection, it will be necessary to define a resource collection:

<?php

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\ResourceCollection;

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

Like singular resources, resource collections may be returned directly from routes or controllers:

use App\User;
use App\Http\Resources\UserCollection;

Route::get('/users', function () {
    return new UserCollection(User::all());
});

Data Wrapping​

By default, your outer-most resource is wrapped in a data key when the resource response is converted to JSON. So, for example, a typical resource collection response looks like the following:

{
    "data": [
        {
            "id": 1,
            "name": "Eladio Schroeder Sr.",
            "email": "therese28@example.com",
        },
        {
            "id": 2,
            "name": "Liliana Mayert",
            "email": "evandervort@example.com",
        }
    ]
}

If you would like to disable the wrapping of the outer-most resource, you may use the withoutWrapping method on the base resource class. Typically, you should call this method from your AppServiceProvider or another service provider that is loaded on every request to your application:

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Illuminate\Http\Resources\Json\Resource;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Perform post-registration booting of services.
     *
     * @return void
     */
    public function boot()
    {
        Resource::withoutWrapping();
    }

    /**
     * Register bindings in the container.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}
备注

The withoutWrapping method only affects the outer-most response and will not remove data keys that you manually add to your own resource collections.

Wrapping Nested Resources​

You have total freedom to determine how your resource's relationships are wrapped. If you would like all resource collections to be wrapped in a data key, regardless of their nesting, you should define a resource collection class for each resource and return the collection within a data key.

Of course, you may be wondering if this will cause your outer-most resource to be wrapped in two data keys. Don't worry, Laravel will never let your resources be accidentally double-wrapped, so you don't have to be concerned about the nesting level of the resource collection you are transforming:

<?php

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\ResourceCollection;

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

Data Wrapping And Pagination​

When returning paginated collections in a resource response, Laravel will wrap your resource data in a data key even if the withoutWrapping method has been called. This is because paginated responses always contain meta and links keys with information about the paginator's state:

{
    "data": [
        {
            "id": 1,
            "name": "Eladio Schroeder Sr.",
            "email": "therese28@example.com",
        },
        {
            "id": 2,
            "name": "Liliana Mayert",
            "email": "evandervort@example.com",
        }
    ],
    "links":{
        "first": "http://example.com/pagination?page=1",
        "last": "http://example.com/pagination?page=1",
        "prev": null,
        "next": null
    },
    "meta":{
        "current_page": 1,
        "from": 1,
        "last_page": 1,
        "path": "http://example.com/pagination",
        "per_page": 15,
        "to": 10,
        "total": 10
    }
}

Pagination​

You may always pass a paginator instance to the collection method of a resource or to a custom resource collection:

use App\User;
use App\Http\Resources\UserCollection;

Route::get('/users', function () {
    return new UserCollection(User::paginate());
});

Paginated responses always contain meta and links keys with information about the paginator's state:

{
    "data": [
        {
            "id": 1,
            "name": "Eladio Schroeder Sr.",
            "email": "therese28@example.com",
        },
        {
            "id": 2,
            "name": "Liliana Mayert",
            "email": "evandervort@example.com",
        }
    ],
    "links":{
        "first": "http://example.com/pagination?page=1",
        "last": "http://example.com/pagination?page=1",
        "prev": null,
        "next": null
    },
    "meta":{
        "current_page": 1,
        "from": 1,
        "last_page": 1,
        "path": "http://example.com/pagination",
        "per_page": 15,
        "to": 10,
        "total": 10
    }
}

Conditional Attributes​

Sometimes you may wish to only include an attribute in a resource response if a given condition is met. For example, you may wish to only include a value if the current user is an "administrator". Laravel provides a variety of helper methods to assist you in this situation. The when method may be used to conditionally add an attribute to a resource response:

/**
 * Transform the resource into an array.
 *
 * @param  \Illuminate\Http\Request
 * @return array
 */
public function toArray($request)
{
    return [
        'id' => $this->id,
        'name' => $this->name,
        'email' => $this->email,
        'secret' => $this->when(Auth::user()->isAdmin(), 'secret-value'),
        'created_at' => $this->created_at,
        'updated_at' => $this->updated_at,
    ];
}

In this example, the secret key will only be returned in the final resource response if the authenticated user's isAdmin method returns true. If the method returns false, the secret key will be removed from the resource response entirely before it is sent back to the client. The when method allows you to expressively define your resources without resorting to conditional statements when building the array.

The when method also accepts a Closure as its second argument, allowing you to calculate the resulting value only if the given condition is true:

'secret' => $this->when(Auth::user()->isAdmin(), function () {
    return 'secret-value';
}),

Merging Conditional Attributes​

Sometimes you may have several attributes that should only be included in the resource response based on the same condition. In this case, you may use the mergeWhen method to include the attributes in the response only when the given condition is true:

/**
 * Transform the resource into an array.
 *
 * @param  \Illuminate\Http\Request
 * @return array
 */
public function toArray($request)
{
    return [
        'id' => $this->id,
        'name' => $this->name,
        'email' => $this->email,
        $this->mergeWhen(Auth::user()->isAdmin(), [
            'first-secret' => 'value',
            'second-secret' => 'value',
        ]),
        'created_at' => $this->created_at,
        'updated_at' => $this->updated_at,
    ];
}

Again, if the given condition is false, these attributes will be removed from the resource response entirely before it is sent to the client.

备注

The mergeWhen method should not be used within arrays that mix string and numeric keys. Furthermore, it should not be used within arrays with numeric keys that are not ordered sequentially.

Conditional Relationships​

In addition to conditionally loading attributes, you may conditionally include relationships on your resource responses based on if the relationship has already been loaded on the model. This allows your controller to decide which relationships should be loaded on the model and your resource can easily include them only when they have actually been loaded.

Ultimately, this makes it easier to avoid "N+1" query problems within your resources. The whenLoaded method may be used to conditionally load a relationship. In order to avoid unnecessarily loading relationships, this method accepts the name of the relationship instead of the relationship itself:

/**
 * Transform the resource into an array.
 *
 * @param  \Illuminate\Http\Request
 * @return array
 */
public function toArray($request)
{
    return [
        'id' => $this->id,
        'name' => $this->name,
        'email' => $this->email,
        'posts' => PostResource::collection($this->whenLoaded('posts')),
        'created_at' => $this->created_at,
        'updated_at' => $this->updated_at,
    ];
}

In this example, if the relationship has not been loaded, the posts key will be removed from the resource response entirely before it is sent to the client.

Conditional Pivot Information​

In addition to conditionally including relationship information in your resource responses, you may conditionally include data from the intermediate tables of many-to-many relationships using the whenPivotLoaded method. The whenPivotLoaded method accepts the name of the pivot table as its first argument. The second argument should be a Closure that defines the value to be returned if the pivot information is available on the model:

/**
 * Transform the resource into an array.
 *
 * @param  \Illuminate\Http\Request
 * @return array
 */
public function toArray($request)
{
    return [
        'id' => $this->id,
        'name' => $this->name,
        'expires_at' => $this->whenPivotLoaded('role_users', function () {
            return $this->pivot->expires_at;
        }),
    ];
}

Adding Meta Data​

Some JSON API standards require the addition of meta data to your resource and resource collections responses. This often includes things like links to the resource or related resources, or meta data about the resource itself. If you need to return additional meta data about a resource, include it in your toArray method. For example, you might include link information when transforming a resource collection:

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

When returning additional meta data from your resources, you never have to worry about accidentally overriding the links or meta keys that are automatically added by Laravel when returning paginated responses. Any additional links you define will be merged with the links provided by the paginator.

Top Level Meta Data​

Sometimes you may wish to only include certain meta data with a resource response if the resource is the outer-most resource being returned. Typically, this includes meta information about the response as a whole. To define this meta data, add a with method to your resource class. This method should return an array of meta data to be included with the resource response only when the resource is the outer-most resource being rendered:

<?php

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\ResourceCollection;

class UserCollection extends ResourceCollection
{
    /**
     * Transform the resource collection into an array.
     *
     * @param  \Illuminate\Http\Request
     * @return array
     */
    public function toArray($request)
    {
        return parent::toArray($request);
    }

    /**
     * Get additional data that should be returned with the resource array.
     *
     * @param \Illuminate\Http\Request  $request
     * @return array
     */
    public function with($request)
    {
        return [
            'meta' => [
                'key' => 'value',
            ],
        ];
    }
}

Adding Meta Data When Constructing Resources​

You may also add top-level data when constructing resource instances in your route or controller. The additional method, which is available on all resources, accepts an array of data that should be added to the resource response:

return (new UserCollection(User::all()->load('roles')))
                ->additional(['meta' => [
                    'key' => 'value',
                ]]);

Resource Responses​

As you have already read, resources may be returned directly from routes and controllers:

use App\User;
use App\Http\Resources\User as UserResource;

Route::get('/user', function () {
    return new UserResource(User::find(1));
});

However, sometimes you may need to customize the outgoing HTTP response before it is sent to the client. There are two ways to accomplish this. First, you may chain the response method onto the resource. This method will return an Illuminate\Http\Response instance, allowing you full control of the response's headers:

use App\User;
use App\Http\Resources\User as UserResource;

Route::get('/user', function () {
    return (new UserResource(User::find(1)))
                ->response()
                ->header('X-Value', 'True');
});

Alternatively, you may define a withResponse method within the resource itself. This method will be called when the resource is returned as the outer-most resource in a response:

<?php

namespace App\Http\Resources;

use Illuminate\Http\Resources\Json\JsonResource;

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

    /**
     * Customize the outgoing response for the resource.
     *
     * @param  \Illuminate\Http\Request
     * @param  \Illuminate\Http\Response
     * @return void
     */
    public function withResponse($request, $response)
    {
        $response->header('X-Value', 'True');
    }
}