Get only one custom post from each category

Question

I have create custom post(book). In which i have five texonomy categories: CatA, CatB, CatC, CatD, CatE. & i want to show only 3 posts and i want that these posts coming from CatA, CatC, CatD.(One post each these categories.)

<?php

        $args = array(
            'post_type' => 'book',
            'posts_per_page' => '3',
            $terms = get_terms( array(
            'taxonomy' => 'categories',
            'field' => 'name',
            'terms' => array('CatA', 'CatB', 'CatC')
            ))
        );

        $query = new WP_Query( $args );

        if ( $query->have_posts() ) { ?>
            <?php while ( $query->have_posts() ) { $query->the_post(); ?>
                <div style="background-image:url('<?php echo get_the_post_thumbnail_url(''`enter code here`);?>')">
                </div>

                <?php the_title();?>

            <?php } // end while ?>

        <?php } wp_reset_postdata(); ?>

Answer 1

You probably need to use a taxonomy query rather than the terms field (I don't see terms as a valid parameter on WordPress's WP_Query documentation page). This stackexchange question and answer should provide you with the necessary code to do what you are trying to do.

If, however, the categories are not custom taxonomies (or really are just categories), then you might be able to use one of the approaches here.

Answer 2

Please Try below code to get only one custom post from each terms. replace terms ids with your term ids in $array_term = array(16,21);

    # pass your term IDS
    $array_term = array(16,21); 
    $terms_array = array( 
      'taxonomy' => 'categories',// you can change it according to your taxonomy
      'include' => $array_term,
      'parent'   => 0 // If parent => 0 is passed, only top-level terms will be returned
    );

    $categories_terms = get_terms($terms_array); 
    foreach($categories_terms as $categorie_term): ?>
        <h4><?php echo $categorie_term->name; ?></h4>
        <?php 
        $post_args = array(
              'posts_per_page' => 1,
              'post_type' => 'book', // you can change it according to your custom post type
              'tax_query' => array(
                  array(
                      'taxonomy' => 'categories', // you can change it according to your taxonomy
                      'field' => 'term_id', // this can be 'term_id', 'slug' & 'name'
                      'terms' => $categorie_term->term_id,
                  )
              )
        );
        $query = new WP_Query($post_args); 
            if ( $query->have_posts() ) 
            {
                while ( $query->have_posts() ) 
                {
                    $query->the_post(); 
                    ?>
                    <li>
                        <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
                     </li>
                    <?php
                }
           }
         wp_reset_postdata(); 
    endforeach; // End Term foreach; 

Let me know if this works for you