Guide

Provide the Resource State

design state

Our model is the same then in the previous guide (Declare a Resource. API Platform will declare CRUD operations if we don't declare them.

// src/App/ApiResource.php
namespace App\ApiResource;
use ApiPlatform\Metadata\ApiResource;
use App\State\BookProvider;

// src/App/ApiResource.php
namespace App\ApiResource;
use ApiPlatform\Metadata\ApiResource;
use App\State\BookProvider;

We use a BookProvider as the ApiResource::provider option.

#[ApiResource(provider: BookProvider::class)]
class Book
{
    public string $id;
}
 
// src/App/State.php
namespace App\State;
use ApiPlatform\Metadata\CollectionOperationInterface;
use ApiPlatform\Metadata\Operation;
use ApiPlatform\State\ProviderInterface;
use App\ApiResource\Book;

#[ApiResource(provider: BookProvider::class)]
class Book
{
    public string $id;
}
 
// src/App/State.php
namespace App\State;
use ApiPlatform\Metadata\CollectionOperationInterface;
use ApiPlatform\Metadata\Operation;
use ApiPlatform\State\ProviderInterface;
use App\ApiResource\Book;

The BookProvider is where we retrieve the data in our persistence layer. In this provider we choose to handle the retrieval of a single Book but also a list of Books.

final class BookProvider implements ProviderInterface
{
    public function provide(Operation $operation, array $uriVariables = [], array $context = []): iterable|object|null
    {
        if ($operation instanceof CollectionOperationInterface) {
            $book = new Book();
            $book->id = '1';

final class BookProvider implements ProviderInterface
{
    public function provide(Operation $operation, array $uriVariables = [], array $context = []): iterable|object|null
    {
        if ($operation instanceof CollectionOperationInterface) {
            $book = new Book();
            $book->id = '1';

As an exercise you can edit the code and add a second book in the collection.

            return [$book];
        }
        $book = new Book();

            return [$book];
        }
        $book = new Book();

The value at $uriVariables['id'] is the one that matches the {id} variable of the URI template.

        $book->id = $uriVariables['id'];
        return $book;
    }
}

        $book->id = $uriVariables['id'];
        return $book;
    }
}