changes-beta-1.md

title	What's Changed: v2 Beta 1

このドキュメントでは、REST APIのバージョン1と2の更新情報の概要について説明します。主な変更点は以下のとおりです。さらにバージョン1から2へ移行する際のサンプルコードも用意しています。

重要: ベータ1は、将来のバージョンで互換性が保障されているわけではありません。公にテストを行うには十分な信頼性があると考えていますが、さらに改善するために互換性がなくなるかもしれません。バージョン2は、本番環境では使用しないで開発環境においてのみ使用してください。

これまで通り、私たちが正しいことをするにも、誤ったことをするにも、みなさんのフィードバックを歓迎します。もし「彼らは何を考えてるんだろう？」と思うようなことがあれば知らせてください。もし何か見逃していることがあれば、ぜひそれを知りたいと思っています。

Key Changes

Internals

• Changed: Endpoints now take a single parameter of type WP_REST_Request. Argument registration has been moved to the route registration. You can now set whether arguments are required with the required option, and a default value with default. (A corresponding rest_ensure_request function has been added to coerce array data to a request object.)

• Added: Route registration can now be done via register_rest_route. This function requires using a namespace. We recommend plugin and theme authors use the plugin slug, followed by a version in the form of /v1; the core API endpoints use the namespace wp/v2

• Changed: All built-in endpoints now use a common Controller base class with a standardised pattern. This is part of the public API for developers, and we recommend you use this when working with most use cases. This simply codifies the best practices in the API core, but is not required in custom code.

• Added: Permission callbacks can now be registered separately to the response callback. This allows us to return richer errors and capability assertions for clients. Use the permission_callback option when registering a route, and return either true if the user has permission to access the API, false or null if the user doesn't have permission, or a WP_Error for a custom error to pass back to the user.

• Added: The server can now validate and sanitize arguments for you, using the validate_callback and sanitize_callback options when registering arguments. The validation callback can return a truthy value for valid parameters, false for invalid parameters, or a WP_Error for a custom error to pass back to the user.

External API

• Changed: Built-in WordPress core routes have moved to the wp/v2 namespace. For example, the posts collection endpoint is now at /wp-json/wp/v2/posts

• Changed: Hypermedia links have changed from meta.links to _links to follow the HAL standard. In custom endpoints, you can either return _links in your data, or use WP_REST_Response->add_link

• Added: Links can now have an embeddable attribute that indicates they can be "embedded" in the response. Pass the &_embed parameter to get back those objects in your response as well.

• Added: Defined content types now also have a schema endpoint, following the JSON Schema standard.

• Changed: Comments have been moved to a top-level endpoint at /wp/v2/comments. To fetch comments belonging to a post, use /wp/v2/comments?post=<id>

Future Changes

We have the following on our mind for further evolution of the API as we progress through to beta 2 and beyond:

• Links from collections
• Schema auto-validation, and further evolution of how we use schemas internally and externally
• User meta access
• Public access to public user data (name, URI, etc) for authors
• Better handling of trashing/permanently deleting

Migrating endpoints from v1 to v2

Migrating endpoints from version 1 code to version 2 is pretty simple, and the easiest way to see this is by example. Let's take an example API:

<?php
add_filter( 'json_endpoints', 'tsla_register_routes' );

function tsla_register_routes( $routes ) {
    $routes[ '/tsla/honk_horn' ] = array( 'tsla_add_horn_honks', WP_JSON_Server::READABLE );
    return $routes;
}

function tsla_add_horn_honks( $honks = 1 ) {
    if ( ! is_numeric( $honks ) ) {
        return new WP_Error( 'tsla_honks_invalid', 'Honks must be a number', array( 'status' => 400 ) );
    }
    $count = get_option( 'wc-heartbeat-honk', 0 );
    update_option( 'wc-heartbeat-honk', $count + $honks );
    $response = new WP_JSON_Response( array( 'result' => true ) );
    $response->header( 'X-Prev-Honks', $count );
    return $response;
}

This is a nice simple API for us to deal with, but has a bit of complexity: it takes (optional) arguments, has error handling, and also has some custom headers. There are a few key changes we need to make here:

• API prefixes have changed from WP_JSON to WP_REST (and filters from json_ to rest_)

• Arguments have changed from mapping to function parameters to taking a single WP_REST_Request object

• Route registration now takes place via a helper function rather than directly via the filter

Here's what the new API looks like:

<?php
add_filter( 'rest_api_init', 'tsla_register_routes' );

function tsla_register_routes( $routes ) {
    register_rest_route( 'tsla', '/honk_horn', array(
        'callback' => 'tsla_add_horn_honks',
        'methods'  => WP_REST_Server::READABLE,
        'args'     => array(
            'honks' => array(
                'required'          => false,
                'validate_callback' => 'is_numeric',
            ),
        )
    ) );
}

function tsla_add_horn_honks( WP_REST_Request $request ) {
    $honks = $request['honks'];
    $count = get_option( 'wc-heartbeat-honk', 0 );
    update_option( 'wc-heartbeat-honk', $count + $honks );
    $response = new WP_REST_Response( array( 'result' => true ) );
    $response->header( 'X-Prev-Honks', $count );
    return $response;
}

You'll notice that a lot of this looks pretty much the same! We've moved our validation check out, and renamed a few things, but otherwise our callback is mostly the same. The route registration has expanded to use the function for registration instead.