title: "控制器类" post_status: publish comment_status: open taxonomy: category: - developer-plugins-handbook post_tag: - Controller Classes - Rest Api - Repos
控制器类
概述
编写端点时，使用控制器类来处理端点功能会很有帮助。控制器类将提供与 API 交互的标准方式，以及更易于维护的交互方式。WordPress 当前最低 PHP 版本为 5.2，如果您开发的端点将被整个 WordPress 生态系统使用，应考虑支持 WordPress 的最低要求。
PHP 5.2 本身不支持命名空间。这意味着您声明的每个函数都将位于全局作用域中。如果您决定为端点使用通用函数名（如 get_items()），而另一个插件也注册了该函数，PHP 将因致命错误而失败。这是因为函数 get_items() 被重复声明。通过封装端点，我们可以避免这些命名冲突，并保持与 API 交互的一致性。
Controllers
Controllers typically do one thing; they receive input, and generate output. For the WordPress REST API our controllers will handle request input as WP_REST_Request objects and generate response output as WP_REST_Response objects. Let’s look at an example controller class:
class My_REST_Posts_Controller {
// Here initialize our namespace and resource name.
public function __construct() {
$this->namespace = '/my-namespace/v1';
$this->resource_name = 'posts';
}
// Register our routes.
public function register_routes() {
register_rest_route( $this->namespace, '/' . $this->resource_name, array(
// Here we register the readable endpoint for collections.
array(
'methods' => 'GET',
'callback' => array( $this, 'get_items' ),
'permission_callback' => array( $this, 'get_items_permissions_check' ),
),
// Register our schema callback.
'schema' => array( $this, 'get_item_schema' ),
) );
register_rest_route( $this->namespace, '/' . $this->resource_name . '/(?P<id>[\d]+)', array(
// Notice how we are registering multiple endpoints the 'schema' equates to an OPTIONS request.
array(
'methods' => 'GET',
'callback' => array( $this, 'get_item' ),
'permission_callback' => array( $this, 'get_item_permissions_check' ),
),
// Register our schema callback.
'schema' => array( $this, 'get_item_schema' ),
) );
}
/**
* Check permissions for the posts.
*
* @param WP_REST_Request $request Current request.
*/
public function get_items_permissions_check( $request ) {
if ( ! current_user_can( 'read' ) ) {
return new WP_Error( 'rest_forbidden', esc_html__( 'You cannot view the post resource.' ), array( 'status' => $this->authorization_status_code() ) );
}
return true;
}
/**
* Grabs the five most recent posts and outputs them as a rest response.
*
* @param WP_REST_Request $request Current request.
*/
public function get_items( $request ) {
$args = array(
'post_per_page' => 5,
);
$posts = get_posts( $args );
$data = array();
if ( empty( $posts ) ) {
return rest_ensure_response( $data );
}
foreach ( $posts as $post ) {
$response = $this->prepare_item_for_response( $post, $request );
$data[] = $this->prepare_response_for_collection( $response );
}
// Return all of our comment response data.
return rest_ensure_response( $data );
}
/**
* Check permissions for the posts.
*
* @param WP_REST_Request $request Current request.
*/
public function get_item_permissions_check( $request ) {
if ( ! current_user_can( 'read' ) ) {
return new WP_Error( 'rest_forbidden', esc_html__( 'You cannot view the post resource.' ), array( 'status' => $this->authorization_status_code() ) );
}
return true;
}
/**
* Grabs the five most recent posts and outputs them as a rest response.
*
* @param WP_REST_Request $request Current request.
*/
public function get_item( $request ) {
$id = (int) $request['id'];
$post = get_post( $id );
if ( empty( $post ) ) {
return rest_ensure_response( array() );
}
$response = prepare_item_for_response( $post );
// Return all of our post response data.
return $response;
}
/**
* Matches the post data to the schema we want.
*
* @param WP_Post $post The comment object whose response is being prepared.
*/
public function prepare_item_for_response( $post, $request ) {
$post_data = array();
$schema = $this->get_item_schema( $request );
// We are also renaming the fields to more understandable names.
if ( isset( $schema['properties']['id'] ) ) {
$post_data['id'] = (int) $post->ID;
}
if ( isset( $schema['properties']['content'] ) ) {
$post_data['content'] = apply_filters( 'the_content', $post->post_content, $post );
}
return rest_ensure_response( $post_data );
}
/**
* Prepare a response for inserting into a collection of responses.
*
* This is copied 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.
*/
public function prepare_response_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;
}
/**
* Get our sample schema for a post.
*
* @param WP_REST_Request $request Current request.
*/
public function get_item_schema( $request ) {
$schema = array(
// This tells the spec of JSON Schema we are using which is draft 4.
'$schema' => 'http://json-schema.org/draft-04/schema#',
// The title property marks the identity of the resource.
'title' => 'post',
'type' => 'object',
// In JSON Schema you can specify object properties in the properties attribute.
'properties' => array(
'id' => array(
'description' => esc_html__( 'Unique identifier for the object.', 'my-textdomain' ),
'type' => 'integer',
'context' => array( 'view', 'edit', 'embed' ),
'readonly' => true,
),
'content' => array(
'description' => esc_html__( 'The content for the object.', 'my-textdomain' ),
'type' => 'string',
),
),
);
return $schema;
}
// 为授权设置正确的 HTTP 状态码。
public function authorization_status_code() {
$status = 401;
if ( is_user_logged_in() ) {
$status = 403;
}
return $status;
}
}
// 用于从控制器注册新路由的函数。
function prefix_register_my_rest_routes() {
$controller = new My_REST_Posts_Controller();
$controller->register_routes();
}
add_action( 'rest_api_init', 'prefix_register_my_rest_routes' );
概述与未来展望
控制器类在开发端点时为我们解决了两个重大问题：命名空间缺失和结构不一致。需要注意的是，不应滥用端点的继承机制。例如：如果您为文章端点编写了控制器类（如上例所示），并希望同时支持自定义文章类型，不应像这样扩展 My_REST_Posts_Controller：class My_CPT_REST_Controller extends My_REST_Posts_Controller。
正确的做法是：要么创建完全独立的控制器类，要么让 My_REST_Posts_Controller 处理所有可用的文章类型。当您开始深入继承机制的黑暗深渊时，必须明白：如果父类在任何时候需要修改，而您的子类又依赖于它们，将会带来巨大麻烦。多数情况下，建议创建基础控制器类作为 接口 或 抽象类，供各个端点控制器实现或扩展。WP REST API 团队正采用 抽象类 方案开发 WP_REST_Controller 类，以期未来能纳入核心代码。
目前，支持文章、文章类型、文章状态、修订版本、分类法、术语、用户、评论及附件/媒体资源的“核心端点”正在功能插件中开发，有望在未来融入 WordPress 核心。该插件内包含一个提案中的 WP_REST_Controller 类，可用于为您的端点构建专属控制器。WP_REST_Controller 具备诸多优势，为 API 端点创建提供了统一规范的方法。