Get a random thumbnail from posts belonging to a specific taxonomy

Question

I have a feeling that I'm on the right track, I just don't have enough solid PHP knowledge to get much further than where I'm currently at.

I'm currently using the following code to return a list of child categories from a single category:

<?php
    $taxonomyName = "category";
    $terms = get_terms($taxonomyName,array('parent' => 79));
    echo '<ul>';
    foreach($terms as $term) {
        echo '<li>';
        echo '<a href="'.get_term_link($term->slug,$taxonomyName).'">'.$term->name.'</a><br/>';

        $thumbnails = get_posts('numberposts=1&orderby=rand');
        foreach ($thumbnails as $thumbnail) {
        echo '<a href="' . get_permalink( $thumbnail->ID ) . '" title="' . esc_attr( $thumbnail->post_title ) . '">';
            if ( has_post_thumbnail($thumbnail->ID)) {
                echo get_the_post_thumbnail($thumbnail->ID, 'thumbnail');
            } else {
            echo 'no thumbnail';    
        }
        echo '</a>';
        }
        echo '<li>';
    }
    echo '</ul>';
?>

This code works somewhat. It returns a list of all six sub categories under the parent, ID 79. However, I want to also return one random thumbnail in each of the list items for each of the 6 sub categories.

Unfortunately, this code returns a random thumbnail from all of my posts, not just ID 79 and it's specific child. I need it to return one thumbnail from the same category that is returned in it's parent <li>.

Is there some easy way to do this? I'm thinking I need to sort through that array and return the category in the nested foreach loop. I just don't know how to do that.

Thanks in advance for any help!

Answer 1

So in order to do this, I needed to first do a for each loop, store the category slug as a variable, JAMterm, and then use that in a query to pull one random thumbnail from the category.

Thanks to @Renishkhunt for helping me along the way to get this answer.

<?php
    $taxonomyName = "category";
    $terms = get_terms($taxonomyName,array('parent' => 79));
    echo '<ul>';
    foreach($terms as $term) {
        echo '<li><a href="'.get_term_link($term->slug,$taxonomyName).'">'.$term->name.'</a><br/>';

        $JAMterm = $term->slug;

        global $wp_query;
        $term = $wp_query->queried_object;

        $args=array(
            'orderby' => 'rand',
            'posts_per_page' => 1,
            'post_type' => 'post',
            'tax_query' => array(
                array(
                    'taxonomy' => 'category', 
                    'field' => 'slug', 
                    'terms' =>  $JAMterm
                )
            )
        );

        $new_query = null;
        $new_query = new WP_Query($args);

        while ($new_query->have_posts()) : $new_query->the_post();
            the_post_thumbnail(); 
        endwhile;
        wp_reset_postdata();


        echo '</li>';
        }
    echo '</ul>';
?>

Answer 2

you also used to display random sub category using shuffle function.

<?php
$term_id = 97;
$taxonomy_name = 'category';
$terms = get_term_children( $term_id, $taxonomy_name );

echo '<ul>';
shuffle($terms);
for($i = 0 ;$i < 1; $i++ ){
    echo '<li>';
    echo '<a href="'.get_term_link($terms[$i]->slug,$taxonomyName).'">'.$terms[$i]->name.'</a><br/>';
        $thumbnails = get_posts('numberposts=1&orderby=rand');
         foreach ($thumbnails as $thumbnail) {
            if ( has_post_thumbnail($thumbnail->ID)) {
                   echo get_the_post_thumbnail($thumbnail->ID, 'thumbnail');
            } else {
                   echo '<a href="' . get_permalink( $thumbnail->ID ) . '" title="' . esc_attr( $thumbnail->post_title ) . '">';
                   echo 'no thumbnail';    
                   echo '</a>';
            }
          }
   echo "</li>";       
}

echo '</ul>';
?> 

i hope this code is used full for you.

this is return random sub category.

thank you.

Answer 3

Since all you want is random thumbnail and not all the posts data, you could use a direct query like this (# please set your real table names or use $wpdb->prefix):

SELECT 
    m.meta_value
FROM 
    wp_posts p 
    INNER JOIN wp_postmeta m ON m.post_id = p.ID
    INNER JOIN wp_term_relationships rel ON p.ID = rel.object_id
    INNER JOIN wp_term_taxonomy tt ON tt.term_taxonomy_id = rel.term_taxonomy_id
    INNER JOIN wp_terms t ON tt.term_id = t.term_id
WHERE 
    p.post_type = 'your post type'  # please set as needed 
    AND p.post_status = 'publish'
    AND m.meta_key = '_thumbnail_id'
    AND t.slug in ('your slug list') # please set as needed
    #AND t.term_id in ('yout id list') # alternative: a list of term ids
ORDER BY RAND()
LIMIT 1

You'll get exactly 1 post thumbnail ID from the list of published posts that belong to a specific term of a specific taxonomy or category. Then get your thumbnail data by using wp_get_attachment_image_url() or some of the other attachment-related functions available form WP.

Generally speaking, when there are no native wordpress functions to retrieve your data, I think it's best to spend some time to build a custom query, since it's often faster and you can then embed it on some utility function to use again when needed.