ルートとエンドポイント

/**
 * This is our callback function that embeds our phrase in a WP_REST_Response
 */
function prefix_get_endpoint_phrase() {
    // rest_ensure_response() wraps the data we want to return into a WP_REST_Response, and ensures it will be properly returned.
    return rest_ensure_response( 'Hello World, this is the WordPress REST API' );
}

/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_example_routes() {
    // register_rest_route() handles more arguments but we are going to stick to the basics for now.
    register_rest_route( 'hello-world/v1', '/phrase', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_endpoint_phrase',
    ) );
}

add_action( 'rest_api_init', 'prefix_register_example_routes' );

/**
 * This is our callback function to return our products.
 *
 * @param WP_REST_Request $request This function accepts a rest request to process data.
 */
function prefix_get_products( $request ) {
    // In practice this function would fetch the desired data. Here we are just making stuff up.
    $products = array(
        '1' => 'I am product 1',
        '2' => 'I am product 2',
        '3' => 'I am product 3',
    );

    return rest_ensure_response( $products );
}

/**
 * This is our callback function to return a single product.
 *
 * @param WP_REST_Request $request This function accepts a rest request to process data.
 */
function prefix_get_product( $request ) {
    // In practice this function would fetch the desired data. Here we are just making stuff up.
    $products = array(
        '1' => 'I am product 1',
        '2' => 'I am product 2',
        '3' => 'I am product 3',
    );

    // Here we are grabbing the 'id' path variable from the $request object. WP_REST_Request implements ArrayAccess, which allows us to grab properties as though it is an array.
    $id = (string) $request['id'];

    if ( isset( $products[ $id ] ) ) {
        // Grab the product.
        $product = $products[ $id ];

        // Return the product as a response.
        return rest_ensure_response( $product );
    } else {
        // Return a WP_Error because the request product was not found. In this case we return a 404 because the main resource was not found.
        return new WP_Error( 'rest_product_invalid', esc_html__( 'The product does not exist.', 'my-text-domain' ), array( 'status' => 404 ) );
    }

    // If the code somehow executes to here something bad happened return a 500.
    return new WP_Error( 'rest_api_sad', esc_html__( 'Something went horribly wrong.', 'my-text-domain' ), array( 'status' => 500 ) );
}

/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_product_routes() {
    // Here we are registering our route for a collection of products.
    register_rest_route( 'my-shop/v1', '/products', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_products',
    ) );
    // Here we are registering our route for single products. The (?P<id>[\d]+) is our path variable for the ID, which, in this example, can only be some form of positive number.
    register_rest_route( 'my-shop/v1', '/products/(?P<id>[\d]+)', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_product',
    ) );
}

add_action( 'rest_api_init', 'prefix_register_product_routes' );

/**
 * This is our callback function to return our products.
 *
 * @param WP_REST_Request $request This function accepts a rest request to process data.
 */
function prefix_get_products( $request ) {
    // In practice this function would fetch the desired data. Here we are just making stuff up.
    $products = array(
        '1' => 'I am product 1',
        '2' => 'I am product 2',
        '3' => 'I am product 3',
    );

    return rest_ensure_response( $products );
}

/**
 * This is our callback function to return a single product.
 *
 * @param WP_REST_Request $request This function accepts a rest request to process data.
 */
function prefix_create_product( $request ) {
    // In practice this function would create a product. Here we are just making stuff up.
   return rest_ensure_response( 'Product has been created' );
}

/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_product_routes() {
    // Here we are registering our route for a collection of products and creation of products.
    register_rest_route( 'my-shop/v1', '/products', array(
        array(
            // By using this constant we ensure that when the WP_REST_Server changes, our readable endpoints will work as intended.
            'methods'  => WP_REST_Server::READABLE,
            // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
            'callback' => 'prefix_get_products',
        ),
        array(
            // By using this constant we ensure that when the WP_REST_Server changes, our create endpoints will work as intended.
            'methods'  => WP_REST_Server::CREATABLE,
            // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
            'callback' => 'prefix_create_product',
        ),
    ) );
}

add_action( 'rest_api_init', 'prefix_register_product_routes' );

/**
 * This is our callback function that embeds our resource in a WP_REST_Response
 */
function prefix_get_private_data() {
    // rest_ensure_response() wraps the data we want to return into a WP_REST_Response, and ensures it will be properly returned.
    return rest_ensure_response( 'This is private data.' );
}

/**
 * This is our callback function that embeds our resource in a WP_REST_Response
 */
function prefix_get_private_data_permissions_check() {
    // Restrict endpoint to only users who have the edit_posts capability.
    if ( ! current_user_can( 'edit_posts' ) ) {
        return new WP_Error( 'rest_forbidden', esc_html__( 'OMG you can not view private data.', 'my-text-domain' ), array( 'status' => 401 ) );
    }

    // This is a black-listing approach. You could alternatively do this via white-listing, by returning false here and changing the permissions check.
    return true;
}

/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_example_routes() {
    // register_rest_route() handles more arguments but we are going to stick to the basics for now.
    register_rest_route( 'my-plugin/v1', '/private-data', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_private_data',
        // Here we register our permissions callback. The callback is fired before the main callback to check if the current user can access the endpoint.
        'permissions_callback' => 'prefix_get_private_data_permissions_check',
    ) );
}

add_action( 'rest_api_init', 'prefix_register_example_routes' );

/**
 * This is our callback function that embeds our resource in a WP_REST_Response
 */
function prefix_get_colors( $request ) {
    // In practice this function would fetch the desired data. Here we are just making stuff up.
    $colors = array(
        'blue',
        'blue',
        'red',
        'red',
        'green',
        'green',
    );

    if ( isset( $request['filter'] ) ) {
       $filtered_colors = array();
       foreach ( $colors as $color ) {
           if ( $request['filter'] === $color ) {
               $filtered_colors[] = $color;
           }
       }
       return rest_ensure_response( $filtered_colors );
    }
    return rest_ensure_response( $colors );
}

/**
 * We can use this function to contain our arguments for the example product endpoint.
 */
function prefix_get_color_arguments() {
    $args = array();
    // Here we are registering the schema for the filter argument.
    $args['filter'] = array(
        // description should be a human readable description of the argument.
        'description' => esc_html__( 'The filter parameter is used to filter the collection of colors', 'my-text-domain' ),
        // type specifies the type of data that the argument should be.
        'type'        => 'string',
        // enum specified what values filter can take on.
        'enum'        => array( 'red', 'green', 'blue' ),
    );
    return $args;
}

/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_example_routes() {
    // register_rest_route() handles more arguments but we are going to stick to the basics for now.
    register_rest_route( 'my-colors/v1', '/colors', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_colors',
        // Here we register our permissions callback. The callback is fired before the main callback to check if the current user can access the endpoint.
        'args' => prefix_get_color_arguments(),
    ) );
}

add_action( 'rest_api_init', 'prefix_register_example_routes' );

/**
 * This is our callback function that embeds our resource in a WP_REST_Response
 */
function prefix_get_colors( $request ) {
    // In practice this function would fetch more practical data. Here we are just making stuff up.
    $colors = array(
        'blue',
        'blue',
        'red',
        'red',
        'green',
        'green',
    );

    if ( isset( $request['filter'] ) ) {
       $filtered_colors = array();
       foreach ( $colors as $color ) {
           if ( $request['filter'] === $color ) {
               $filtered_colors[] = $color;
           }
       }
       return rest_ensure_response( $filtered_colors );
    }
    return rest_ensure_response( $colors );
}
/**
 * Validate a request argument based on details registered to the route.
 *
 * @param  mixed            $value   Value of the 'filter' argument.
 * @param  WP_REST_Request  $request The current request object.
 * @param  string           $param   Key of the parameter. In this case it is 'filter'.
 * @return WP_Error|boolean
 */
function prefix_filter_arg_validate_callback( $value, $request, $param ) {
    // If the 'filter' argument is not a string return an error.
    if ( ! is_string( $value ) ) {
        return new WP_Error( 'rest_invalid_param', esc_html__( 'The filter argument must be a string.', 'my-text-domain' ), array( 'status' => 400 ) );
    }

    // Get the registered attributes for this endpoint request.
    $attributes = $request->get_attributes();

    // Grab the filter param schema.
    $args = $attributes['args'][ $param ];

    // If the filter param is not a value in our enum then we should return an error as well.
    if ( ! in_array( $value, $args['enum'], true ) ) {
        return new WP_Error( 'rest_invalid_param', sprintf( __( '%s is not one of %s' ), $param, implode( ', ', $args['enum'] ) ), array( 'status' => 400 ) );
    }
}

/**
 * We can use this function to contain our arguments for the example product endpoint.
 */
function prefix_get_color_arguments() {
    $args = array();
    // Here we are registering the schema for the filter argument.
    $args['filter'] = array(
        // description should be a human readable description of the argument.
        'description' => esc_html__( 'The filter parameter is used to filter the collection of colors', 'my-text-domain' ),
        // type specifies the type of data that the argument should be.
        'type'        => 'string',
        // enum specified what values filter can take on.
        'enum'        => array( 'red', 'green', 'blue' ),
        // Here we register the validation callback for the filter argument.
        'validate_callback' => 'prefix_filter_arg_validate_callback',
    );
    return $args;
}

/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_example_routes() {
    // register_rest_route() handles more arguments but we are going to stick to the basics for now.
    register_rest_route( 'my-colors/v1', '/colors', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_colors',
        // Here we register our permissions callback. The callback is fired before the main callback to check if the current user can access the endpoint.
        'args' => prefix_get_color_arguments(),
    ) );
}

add_action( 'rest_api_init', 'prefix_register_example_routes' );

/**
 * This is our callback function that embeds our resource in a WP_REST_Response.
 *
 * The parameter is already sanitized by this point so we can use it without any worries.
 */
function prefix_get_item( $request ) {
    if ( isset( $request['data'] ) ) {
        return rest_ensure_response( $request['data'] );
    }

    return new WP_Error( 'rest_invalid', esc_html__( 'The data parameter is required.', 'my-text-domain' ), array( 'status' => 400 ) );
}

/**
 * Validate a request argument based on details registered to the route.
 *
 * @param  mixed            $value   Value of the 'filter' argument.
 * @param  WP_REST_Request  $request The current request object.
 * @param  string           $param   Key of the parameter. In this case it is 'filter'.
 * @return WP_Error|boolean
 */
function prefix_data_arg_validate_callback( $value, $request, $param ) {
    // If the 'data' argument is not a string return an error.
    if ( ! is_string( $value ) ) {
        return new WP_Error( 'rest_invalid_param', esc_html__( 'The filter argument must be a string.', 'my-text-domain' ), array( 'status' => 400 ) );
    }
}

/**
 * Sanitize a request argument based on details registered to the route.
 *
 * @param  mixed            $value   Value of the 'filter' argument.
 * @param  WP_REST_Request  $request The current request object.
 * @param  string           $param   Key of the parameter. In this case it is 'filter'.
 * @return WP_Error|boolean
 */
function prefix_data_arg_sanitize_callback( $value, $request, $param ) {
    // It is as simple as returning the sanitized value.
    return sanitize_text_field( $value );
}

/**
 * We can use this function to contain our arguments for the example product endpoint.
 */
function prefix_get_data_arguments() {
    $args = array();
    // Here we are registering the schema for the filter argument.
    $args['data'] = array(
        // description should be a human readable description of the argument.
        'description' => esc_html__( 'The data parameter is used to be sanitized and returned in the response.', 'my-text-domain' ),
        // type specifies the type of data that the argument should be.
        'type'        => 'string',
        // Set the argument to be required for the endpoint.
        'required'    => true,
        // We are registering a basic validation callback for the data argument.
        'validate_callback' => 'prefix_data_arg_validate_callback',
        // Here we register the validation callback for the filter argument.
        'sanitize_callback' => 'prefix_data_arg_sanitize_callback',
    );
    return $args;
}

/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_example_routes() {
    // register_rest_route() handles more arguments but we are going to stick to the basics for now.
    register_rest_route( 'my-plugin/v1', '/sanitized-data', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_item',
        // Here we register our permissions callback. The callback is fired before the main callback to check if the current user can access the endpoint.
        'args' => prefix_get_data_arguments(),
    ) );
}

add_action( 'rest_api_init', 'prefix_register_example_routes' );