List the authors that have written posts in a category

Question

How can I list the authors of posts in a category in WordPress?

On my blog have three authors and I want to list who written the posts in a category. For example:

CAT NAME: INTERNET     AUTHOR: JOHN, DOE, ALEX
CAT NAME: TECH         AUTHOR: JOHN
CAT NAME: CODE         AUTHOR: ALEX

Answer 1

I found a solution.

CODE:

  <?php
    $cat_arr = get_categories(); // Get the list of Categories
    foreach ($cat_arr as $cat_obj) {
        $term_id = $cat_obj->term_id;

        // Print the Name
        ?>
        <br>
        CAT NAME: <?php echo $cat_obj->name ?>, AUTHOR: 
        <?php
        // Get all Posts of that Category
        $posts = get_posts(array('category'=>$term_id));

        $authors_arr = array();
        foreach ($posts as $post_obj) {
            $author_id = $post_obj->post_author;

                // In depends on where you put this code, the include of the file is required
            if (!function_exists('get_userdata')) {
                include '<your WP folder>/wp-includes/pluggable.php';
            }

            $user_obj = get_userdata($author_id);
                // Only Add the author is isn't already added, to avoid printed twice
            if (!in_array($user_obj->user_login, $authors_arr)) {
                $authors_arr[] = $user_obj->user_login; // Instead of user_login you can use any Database field of the "Users" table
            }
        }
        echo implode(', ', $authors_arr) . '<br>';
    }
    ?>

Answer 2

WordPress Categories don't have authors in the traditional sense of the term. You should read up on the WordPress Taxonomies and also look through your wp_terms, wp_term_taxonomy and wp_term_relationships tables to see how WordPress organizes and uses that data.