wordpress wp_query not working with post_parent - php

Question

The wp_query below does not work when using the post_parent operator.
If I remove this option the query runs but when I add back in, it does not.
I have identified the post parent id from the category URL in the admin and it's definitely correct with 24 posts in that category.
the url for the category is wp-admin/term.php?taxonomy=category&tag_ID=2893&post_type=post&wp_http_referer=%2Fwp-admin%2Fedit-tags.php%3Ftaxonomy%3Dcategory
<?php
// WP_Query arguments
$args = array(
'post_parent' => '2893',
'post_type' => 'post',
//'post_status' => array( 'publish' ),
//'nopaging' => true,
// 'order' => 'ASC',
// 'orderby' => 'title'
);
// The Query
$sizes = new WP_Query( $args );
// The Loop
if ( $sizes->have_posts() ) {
while ( $sizes->have_posts() ) {
$sizes->the_title();
}
} else {
echo 'nothing here...';
}
// Restore original Post Data
wp_reset_postdata(); ?>

Answer 1

If you want to list pages that are tagged with a category term (by id) you will have to use 'category__in' => array() instead.
The post_parent argument is for getting pages ( or CPTs that are hierarchical ) where the ID passed is the page/post which is set as parent to other pages.
Example usage of getting posts tagged with category id:
$args = array(
'category__in' => array($cat_id_1, $cat_id_2) // Where $cat_id_x is an integer of the category ID (2893 in your case).
);

Answer 2

Pass the argument as an integer, not a string ;)
<?php
// WP_Query arguments.
$args = array(
'post_parent' => 2893, // This should be integer.
'post_type' => 'post',
// 'post_status' => array( 'publish' ),
// 'nopaging' => true,
// 'order' => 'ASC',
// 'orderby' => 'title',
);
// The Query.
$sizes = new WP_Query( $args );
// The Loop.
if ( $sizes->have_posts() ) {
while ( $sizes->have_posts() ) {
$sizes->the_title();
}
} else {
echo 'nothing here...';
}
// Restore original Post Data.
wp_reset_postdata();