リクエスト

$request = new WP_REST_Request( 'GET', '/my-namespace/v1/examples' );

// Register our individual books endpoint.
function prefix_register_book_route() {
    register_rest_route( 'my-namespace/v1', '/books/(?P<id>\d+)', array(
        // Supported methods for this endpoint. WP_REST_Server::READABLE translates to GET.
        'methods' => WP_REST_Server::READABLE,
        // Register the callback for the endpoint.
        'callback' => 'prefix_get_book',
    ) );
}

add_action( 'rest_api_init', 'prefix_register_book_route' ); 

/**
 * Our registered endpoint callback. Notice how we are passing in $request as an argument.
 * By default, the WP_REST_Server will pass in the matched request object to our callback.
 *
 * @param WP_REST_Request $request The current matched request object.
 */
function prefix_get_book( $request ) {
    // Here we are accessing the path variable 'id' from the $request.
    $book = prefix_get_the_book( $request['id'] );
    return rest_ensure_response( $book );
}

// A simple function that grabs a book title from our books by ID.
function prefix_get_the_book( $id ) {
    $books = array(
        'Design Patterns',
        'Clean Code',
        'Refactoring',
        'Structure and Interpretation of Computer Programs',
    );

    $book = '';
    if ( isset( $books[ $id ] ) ) {
        // Grab the matching book.
        $book = $books[ $id ];
    } else {
        // Error handling.
        return new WP_Error( 'rest_not_found', esc_html__( 'The book does not exist', 'my-text-domain' ), array( 'status' => 404 ) );
    }

    return $book;
}

{
  "methods": {
    "GET": true
  },
  "accept_json": false,
  "accept_raw": false,
  "show_in_index": true,
  "args": {
    "context": {
      "description": "Scope under which the request is made; determines fields present in response.",
      "type": "string",
      "sanitize_callback": "sanitize_key",
      "validate_callback": "rest_validate_request_arg",
      "enum": [
        "view",
        "embed",
        "edit"
      ],
      "default": "view"
    },
    "page": {
      "description": "Current page of the collection.",
      "type": "integer",
      "default": 1,
      "sanitize_callback": "absint",
      "validate_callback": "rest_validate_request_arg",
      "minimum": 1
    },
    "per_page": {
      "description": "Maximum number of items to be returned in result set.",
      "type": "integer",
      "default": 10,
      "minimum": 1,
      "maximum": 100,
      "sanitize_callback": "absint",
      "validate_callback": "rest_validate_request_arg"
    },
    "search": {
      "description": "Limit results to those matching a string.",
      "type": "string",
      "sanitize_callback": "sanitize_text_field",
      "validate_callback": "rest_validate_request_arg"
    },
    "after": {
      "description": "Limit response to resources published after a given ISO8601 compliant date.",
      "type": "string",
      "format": "date-time",
      "validate_callback": "rest_validate_request_arg"
    },
    "author": {
      "description": "Limit result set to posts assigned to specific authors.",
      "type": "array",
      "default": [],
      "sanitize_callback": "wp_parse_id_list",
      "validate_callback": "rest_validate_request_arg"
    },
    "author_exclude": {
      "description": "Ensure result set excludes posts assigned to specific authors.",
      "type": "array",
      "default": [],
      "sanitize_callback": "wp_parse_id_list",
      "validate_callback": "rest_validate_request_arg"
    },
    "before": {
      "description": "Limit response to resources published before a given ISO8601 compliant date.",
      "type": "string",
      "format": "date-time",
      "validate_callback": "rest_validate_request_arg"
    },
    "exclude": {
      "description": "Ensure result set excludes specific ids.",
      "type": "array",
      "default": [],
      "sanitize_callback": "wp_parse_id_list"
    },
    "include": {
      "description": "Limit result set to specific ids.",
      "type": "array",
      "default": [],
      "sanitize_callback": "wp_parse_id_list"
    },
    "offset": {
      "description": "Offset the result set by a specific number of items.",
      "type": "integer",
      "sanitize_callback": "absint",
      "validate_callback": "rest_validate_request_arg"
    },
    "order": {
      "description": "Order sort attribute ascending or descending.",
      "type": "string",
      "default": "desc",
      "enum": [
        "asc",
        "desc"
      ],
      "validate_callback": "rest_validate_request_arg"
    },
    "orderby": {
      "description": "Sort collection by object attribute.",
      "type": "string",
      "default": "date",
      "enum": [
        "date",
        "relevance",
        "id",
        "include",
        "title",
        "slug"
      ],
      "validate_callback": "rest_validate_request_arg"
    },
    "slug": {
      "description": "Limit result set to posts with a specific slug.",
      "type": "string",
      "validate_callback": "rest_validate_request_arg"
    },
    "status": {
      "default": "publish",
      "description": "Limit result set to posts assigned a specific status; can be comma-delimited list of status types.",
      "enum": [
        "publish",
        "future",
        "draft",
        "pending",
        "private",
        "trash",
        "auto-draft",
        "inherit",
        "any"
      ],
      "sanitize_callback": "sanitize_key",
      "type": "string",
      "validate_callback": [
        {},
        "validate_user_can_query_private_statuses"
      ]
    },
    "filter": {
      "description": "Use WP Query arguments to modify the response; private query vars require appropriate authorization."
    },
    "categories": {
      "description": "Limit result set to all items that have the specified term assigned in the categories taxonomy.",
      "type": "array",
      "sanitize_callback": "wp_parse_id_list",
      "default": []
    },
    "tags": {
      "description": "Limit result set to all items that have the specified term assigned in the tags taxonomy.",
      "type": "array",
      "sanitize_callback": "wp_parse_id_list",
      "default": []
    }
  },
  "callback": [
    {},
    "get_items"
  ],
  "permission_callback": [
    {},
    "get_items_permissions_check"
  ]
}

// Register our mock batch endpoint.
function prefix_register_batch_route() {
    register_rest_route( 'my-namespace/v1', '/batch', array(
        // Supported methods for this endpoint. WP_REST_Server::READABLE translates to GET.
        'methods' => WP_REST_Server::READABLE,
        // Register the callback for the endpoint.
        'callback' => 'prefix_do_batch_request',
        // Register args for the batch endpoint.
        'args' => prefix_batch_request_parameters(),
    ) );
}

add_action( 'rest_api_init', 'prefix_register_batch_route' );

/**
 * Our registered endpoint callback. Notice how we are passing in $request as an argument.
 * By default, the WP_REST_Server will pass in the matched request object to our callback.
 *
 * @param WP_REST_Request $request The current matched request object.
 */
function prefix_do_batch_request( $request ) {
    // Here we initialize the array that will hold our response data.
    $data = array();
	$data = prefix_handle_batch_requests( $request['requests'] );
	return $data;
}

/**
 * This handles the building of the response for the batch requests we make.
 *
 * @param array $requests An array of data to build WP_REST_Request objects from.
 * @return WP_REST_Response A collection of response data for batch endpoints.
 */
function prefix_handle_batch_requests( $requests ) {
	$data = array();

	// Foreach request specified in the requests param run the endpoint.
	foreach ( $requests as $request_params ) {
		$response = prefix_handle_request( $request_params );
		$key = $request_params['method'] . ' ' . $request_params['route'];
		$data[ $key ] = prefix_prepare_for_collection( $response );
	}

	return rest_ensure_response( $data );
}

/**
 * This handles the building of the response for the batch requests we make.
 *
 * @param array $request_params Data to build a WP_REST_Request object from.
 * @return WP_REST_Response Response data for the request.
 */
function prefix_handle_request( $request_params ) {
	$request = new WP_REST_Request( $request_params['method'], $request_params['route'] );

	// Add specified request parameters into the request.
	if ( isset( $request_params['params'] ) ) {
		foreach ( $request_params['params'] as $param_name => $param_value ) {
			$request->set_param( $param_name, $param_value );
		}
	}
	$response = rest_do_request( $request );
	return $response;
}

/**
 * Prepare a response for inserting into a collection of responses.
 *
 * This is lifted from WP_REST_Controller class in the WP REST API v2 plugin.
 *
 * @param WP_REST_Response $response Response object.
 * @return array Response data, ready for insertion into collection data.
 */
function prefix_prepare_for_collection( $response ) {
	if ( ! ( $response instanceof WP_REST_Response ) ) {
		return $response;
	}

	$data = (array) $response->get_data();
	$server = rest_get_server();

	if ( method_exists( $server, 'get_compact_response_links' ) ) {
		$links = call_user_func( array( $server, 'get_compact_response_links' ), $response );
	} else {
		$links = call_user_func( array( $server, 'get_response_links' ), $response );
	}

	if ( ! empty( $links ) ) {
		$data['_links'] = $links;
	}

	return $data;
}

/**
 * Returns the JSON schema data for our registered parameters.
 *
 * @return array $params A PHP representation of JSON Schema data.
 */
function prefix_batch_request_parameters() {
    $params = array();

    $params['requests'] = array(
		'description'        => esc_html__( 'An array of request objects arguments that can be built into WP_REST_Request instances.', 'my-text-domain' ),
		'type'               => 'array',
		'required'           => true,
		'validate_callback'  => 'prefix_validate_requests',
		'items'              => array(
			array(
				'type' => 'object',
				'properties' => array(
					'method' => array(
						'description' => esc_html__( 'HTTP Method of the desired request.', 'my-text-domain' ),
						'type'        => 'string',
						'required'    => true,
						'enum'        => array(
							'GET',
							'POST',
							'PUT',
							'DELETE',
							'OPTIONS',
						),
					),
					'route' => array(
						'description' => esc_html__( 'Desired route for the request.', 'my-text-domain' ),
						'required'    => true,
						'type'        => 'string',
						'format'      => 'uri',
					),
					'params' => array(
						'description' => esc_html__( 'Key value pairs of desired request parameters.', 'my-text-domain' ),
						'type' => 'object',
					),
				),
			),
		),
	);

	return $params;
}

function prefix_validate_requests( $requests, $request, $param_key ) {
	// If requests isn't an array of requests then we don't process the batch.
	if ( ! is_array( $requests ) ) {
		return new WP_Error( 'rest_invald_param', esc_html__( 'The requests parameter must be an array of requests.' ), array( 'status' => 400 ) );
	}

	foreach ( $requests as $request ) {
		// If the method or route is not set then we do not run the requests.
		if ( ! isset( $request['method'] ) || ! isset( $request['route'] ) ) {
			return new WP_Error( 'rest_invald_param', esc_html__( 'You must specify the method and route for each request.' ), array( 'status' => 400 ) );
		}

		if ( isset( $request['params'] ) && ! is_array( $request['params'] ) ) {
			return new WP_Error( 'rest_invald_param', esc_html__( 'You must specify the params for each request as an array of named key value pairs.' ), array( 'status' => 400 ) );
		}
	}

	// This is a black listing approach to data validation.
	return true;
}