List all posts in taxonomy term

Question

I have a custom post type called anime and a taxonomy called series. If I view any post and that post belongs term Banana it should list all the posts in term Banana in a dropdown list. Here's the code so far:

<?php 
    $category = get_terms( 'series' );
    $catID = $category[0]->term_id;
    $args = array(
        'numberposts' => 5, 
        'category' => $catID,
        'post_type' => 'anime'          
    );
    $catPosts = get_posts( $args );

    echo '<form method="POST">';
    echo '<select name="goToPost" onchange="document.location=this.value">';
    echo '<option value="">'.__('Relevent Posts', 'your_text_domain').'</option>';  
    foreach( $catPosts as $singlePost ) {
    echo '<option value="'.get_bloginfo('url').'/index.php?p='.$singlePost->ID.'">'.$singlePost->post_title.'</option>';
    };
    echo '</select>';
    echo '</form>';
?> 

But it's not working right. it's basically listing all posts in the taxonomy and not within the term

Answer 1

You should be using a tax_query for this operation. The category parameters won't work with custom taxonomies

Instead of

'category' => $catID,

use

'tax_query' => array(
        array(
            'taxonomy'          => 'series',
            'field'             => 'term_id',
            'terms'             => $catID,
            'include_children'  => false
        ),
    ),