hdh_rest_api.php

<?php
/*
Plugin Name: REST API Custom
Plugin URI: http://hungdh.me
Description: Add metadata, end point to the REST API
Author: Huy Hung
Version: 1.0
Author URI: http://hungdh.me
*/


/**
 *
 * Thêm api lấy danh sách bài viết theo category
 * Querry: /wp-json/wp/v2/get_category_posts/cat=2&page=1/
 */
add_action( 'rest_api_init', 'hdh_register_end_point_category' );
function hdh_register_end_point_category() {
    register_rest_route( 'wp/v2', '/get_category_posts/cat=(?P<cat_id>\d+)&page=(?P<page_id>\d+)', 
        array(
        'methods' => 'GET',
        'callback' => 'hdh_getPostByCategory',
    ) );
}

function hdh_getPostByCategory($data){
    wp_reset_postdata();
    wp_reset_query();
    $category = get_category($data['cat_id']);

    $cate['id'] = $category->cat_ID;    
    $cate['name'] = $category->name;
    $cate['slug'] = $category->slug;    
    $cate['description'] = $category->category_description;
    $cate['total'] = $category->category_count;
    $pages = intval($cate['total'] / 10);
    if($pages*10 != $cate['total'])
        $pages++;
    $cate['pages'] = $pages;
      
    if($data['page_id'] > $pages){
        $cate['count'] = 0;
        return $cate;
    }

    $query = array(
        'offset' => ($data['page_id']-1)*10,
        'posts_per_page' => 10, 
        'cat' => $data['cat_id'],
        'orderby'=> 'date',
        'order' => 'des'
    );
    
    $list_posts = array();
    $cf = new WP_Query($query);
    $count = 0;
    while ($cf->have_posts()) : $cf->the_post();
        $post['id'] = get_the_ID();
        $post['title']['rendered'] = get_the_title();        
        $post['link'] = get_the_permalink();
        $post['thumbnail'] = wp_get_attachment_url(get_post_thumbnail_id(get_the_ID())); 
        $post['post_views_count'] = intval(trim(get_post_meta( get_the_ID(), 'post_views_count', true )));
        $post['status'] = trim(get_post_meta(get_the_ID(), 'status', true));
        $post['chapter_count'] = intval(trim(get_post_meta(get_the_ID(), 'chapter_count', true)));
        $count++;             
        array_push($list_posts, $post);
    endwhile;    
    wp_reset_postdata(); 
    $cate['count'] = $count;
    $cate['posts'] = $list_posts;    
    return $cate;
}
?>