Wordpress: Display image attachments from child pages of a specific page - php

Question

I am trying to display all image attachments on the child pages of a specific parent page, i.e. all the pictures on Pages 10, 11 and 12.
Projects (Page ID: 5)
- Project 1 (Page ID: 10)
- Project 2 (Page ID: 11)
- Project 3 (Page ID: 12)
This is what I have so far, and it works to display all images on the site:
<?php
$args = array(
'post_parent' => 0,
'post_type' => 'attachment',
'numberposts' => -1
);
$images = get_children( $args );
if ( empty($images) ) {
// no attachments here
} else {
foreach ( $images as $attachment_id => $attachment ) {
echo wp_get_attachment_image( $attachment_id, 'full' );
}
}
?>
However, if I add the post parent ID (5), nothing comes up:
<?php
$args = array(
'post_parent' => 5,
'post_type' => 'attachment',
'numberposts' => -1
);
$images = get_children( $args );
if ( empty($images) ) {
// no attachments here
} else {
foreach ( $images as $attachment_id => $attachment ) {
echo wp_get_attachment_image( $attachment_id, 'full' );
}
}
?>
Any suggestions would be really helpful!

Answer 1

I think get_children() return objects from a single parent post or all (passing 0 as value).
You may try a nested foreach to get all post children first, then query attachment page by page. Here is an untested sample, but it gives you an idea:
<?php
$subpages_args = array(
'post_parent' => 5,
'post_type' => 'page',
'numberposts' => -1
);
$sub_pages = get_children( $subpages_args );
foreach( $sub_pages as $subpage_id => $sub_page) {
$args = array(
'post_parent' => subpage_id,
'post_type' => 'attachment',
'numberposts' => -1
);
$images = get_children( $args );
if ( empty($images) ) {
// no attachments here
} else {
foreach ( $images as $attachment_id => $attachment ) {
echo wp_get_attachment_image( $attachment_id, 'full' );
}
}
}
?>
Good luck :)

Answer 2

Here is an SQL Query based solution. Copy following function in your theme's functions.php
function get_children_page_attachments($parent_id) {
global $wpdb;
// just a precautionary typecast and check
$parent_id = intval( $parent_id );
if( empty($parent_id) ) return [];
$query = "SELECT ID FROM {$wpdb->posts} P WHERE post_type='attachment' AND P.post_parent IN (SELECT ID FROM {$wpdb->posts} WHERE post_parent={$parent_id} AND post_type='page' )";
return $wpdb->get_results($query, 'ARRAY_A');
}
Once you have above function in your functions.php, then you can use it like this:
// for example the parent page id is 16
$image_ids = get_children_page_attachments(16);
foreach($image_ids as $image_id) {
$image = wp_get_attachment_image($image_id['ID'], 'full');
}