wordpress-advanced-architecture

What this skill does

# Advanced WordPress Architecture

Master advanced WordPress development patterns including REST API endpoints, WP-CLI commands, performance optimization, and caching strategies for scalable WordPress applications.

## 1. REST API Development

The WordPress REST API provides a powerful interface for creating custom endpoints with proper authentication, validation, and response formatting.

### Endpoint Registration with Namespacing

```php
add_action( 'rest_api_init', 'register_custom_rest_routes' );
function register_custom_rest_routes() {
    // Namespace: myplugin/v1 (enables versioning)
    $namespace = 'myplugin/v1';

    // GET /wp-json/myplugin/v1/books
    register_rest_route( $namespace, '/books', [
        'methods'  => 'GET',
        'callback' => 'get_books_callback',
        'permission_callback' => '__return_true', // Public endpoint
        'args' => [
            'per_page' => [
                'default' => 10,
                'validate_callback' => function( $param ) {
                    return is_numeric( $param ) && $param > 0 && $param <= 100;
                },
                'sanitize_callback' => 'absint',
            ],
            'page' => [
                'default' => 1,
                'validate_callback' => function( $param ) {
                    return is_numeric( $param ) && $param > 0;
                },
                'sanitize_callback' => 'absint',
            ],
        ],
    ]);

    // GET /wp-json/myplugin/v1/books/(?P<id>\d+)
    register_rest_route( $namespace, '/books/(?P<id>\d+)', [
        'methods'  => 'GET',
        'callback' => 'get_book_callback',
        'permission_callback' => '__return_true',
        'args' => [
            'id' => [
                'validate_callback' => function( $param ) {
                    return is_numeric( $param );
                },
                'sanitize_callback' => 'absint',
            ],
        ],
    ]);

    // POST /wp-json/myplugin/v1/books (authenticated)
    register_rest_route( $namespace, '/books', [
        'methods'  => 'POST',
        'callback' => 'create_book_callback',
        'permission_callback' => function() {
            return current_user_can( 'edit_posts' );
        },
        'args' => [
            'title' => [
                'required' => true,
                'type' => 'string',
                'validate_callback' => function( $param ) {
                    return is_string( $param ) && strlen( $param ) > 0;
                },
                'sanitize_callback' => 'sanitize_text_field',
            ],
            'content' => [
                'required' => false,
                'type' => 'string',
                'sanitize_callback' => 'wp_kses_post',
            ],
            'status' => [
                'default' => 'draft',
                'enum' => [ 'draft', 'publish', 'private' ],
            ],
        ],
    ]);

    // PUT /wp-json/myplugin/v1/books/(?P<id>\d+)
    register_rest_route( $namespace, '/books/(?P<id>\d+)', [
        'methods'  => 'PUT',
        'callback' => 'update_book_callback',
        'permission_callback' => function( $request ) {
            $book_id = $request->get_param( 'id' );
            return current_user_can( 'edit_post', $book_id );
        },
        'args' => [
            'id' => [
                'validate_callback' => function( $param ) {
                    return is_numeric( $param );
                },
                'sanitize_callback' => 'absint',
            ],
            'title' => [
                'type' => 'string',
                'sanitize_callback' => 'sanitize_text_field',
            ],
            'content' => [
                'type' => 'string',
                'sanitize_callback' => 'wp_kses_post',
            ],
        ],
    ]);

    // DELETE /wp-json/myplugin/v1/books/(?P<id>\d+)
    register_rest_route( $namespace, '/books/(?P<id>\d+)', [
        'methods'  => 'DELETE',
        'callback' => 'delete_book_callback',
        'permission_callback' => function( $request ) {
            $book_id = $request->get_param( 'id' );
            return current_user_can( 'delete_post', $book_id );
        },
        'args' => [
            'id' => [
                'validate_callback' => function( $param ) {
                    return is_numeric( $param );
                },
                'sanitize_callback' => 'absint',
            ],
        ],
    ]);
}
```

### Complete CRUD Implementation

```php
// GET /wp-json/myplugin/v1/books
function get_books_callback( $request ) {
    $per_page = $request->get_param( 'per_page' );
    $page = $request->get_param( 'page' );
    $offset = ( $page - 1 ) * $per_page;

    $args = [
        'post_type' => 'book',
        'posts_per_page' => $per_page,
        'offset' => $offset,
        'post_status' => 'publish',
    ];

    $query = new WP_Query( $args );

    if ( ! $query->have_posts() ) {
        return rest_ensure_response([
            'books' => [],
            'total' => 0,
            'page' => $page,
            'per_page' => $per_page,
        ]);
    }

    $books = [];
    while ( $query->have_posts() ) {
        $query->the_post();
        $books[] = [
            'id' => get_the_ID(),
            'title' => get_the_title(),
            'content' => get_the_content(),
            'author' => get_the_author(),
            'date' => get_the_date( 'c' ), // ISO 8601 format
            'link' => get_permalink(),
        ];
    }
    wp_reset_postdata();

    $response = rest_ensure_response([
        'books' => $books,
        'total' => $query->found_posts,
        'page' => $page,
        'per_page' => $per_page,
        'total_pages' => ceil( $query->found_posts / $per_page ),
    ]);

    // Add HATEOAS links
    $response->add_link( 'self', rest_url( "myplugin/v1/books?page={$page}&per_page={$per_page}" ) );

    if ( $page > 1 ) {
        $prev_page = $page - 1;
        $response->add_link( 'prev', rest_url( "myplugin/v1/books?page={$prev_page}&per_page={$per_page}" ) );
    }

    if ( $page < ceil( $query->found_posts / $per_page ) ) {
        $next_page = $page + 1;
        $response->add_link( 'next', rest_url( "myplugin/v1/books?page={$next_page}&per_page={$per_page}" ) );
    }

    return $response;
}

// GET /wp-json/myplugin/v1/books/123
function get_book_callback( $request ) {
    $book_id = $request->get_param( 'id' );
    $book = get_post( $book_id );

    if ( ! $book || 'book' !== $book->post_type ) {
        return new WP_Error(
            'book_not_found',
            'Book not found',
            [ 'status' => 404 ]
        );
    }

    $data = [
        'id' => $book->ID,
        'title' => $book->post_title,
        'content' => apply_filters( 'the_content', $book->post_content ),
        'excerpt' => $book->post_excerpt,
        'author' => get_the_author_meta( 'display_name', $book->post_author ),
        'date' => get_the_date( 'c', $book ),
        'modified' => get_the_modified_date( 'c', $book ),
        'status' => $book->post_status,
        'link' => get_permalink( $book ),
        'featured_image' => get_the_post_thumbnail_url( $book, 'large' ),
        'meta' => [
            'isbn' => get_post_meta( $book->ID, '_isbn', true ),
            'pages' => (int) get_post_meta( $book->ID, '_pages', true ),
        ],
    ];

    return rest_ensure_response( $data );
}

// POST /wp-json/myplugin/v1/books
function create_book_callback( $request ) {
    $title = $request->get_param( 'title' );
    $content = $request->get_param( 'content' );
    $status = $request->get_param( 'status' );

    $post_data = [
        'post_type' => 'book',
        'post_title' => $title,
        'post_content' => $content,
        'post_status' => $status,
        'post_author' => get_current_user_id(),
    ];

    $book_id = wp_insert_post( $post_data, true );

    if ( is_wp_error( $book_id ) ) {
        return new WP_Error(
            'book_creation_failed',
            $book_id->get_error_message(),