Display (Wordpress) Child Pages with Title, Thumbnail and Excerpt - php

Question

Apologies in advance for a question, which to an expert, I've no doubt is relatively obvious. I've looked at WordPress Codex for the appropriate information (the_post_thumbnail, the_excerpt, etc) but am not well versed enough in .php yet to implement it properly. Still learning!
I am trying to display, within the of a standard (WP) page, the child-pages, including their Title, Thumbnail and Excerpt. I can get everything to work bar the THUMBNAIL and EXCERPT with the following:
<div class="child-pages">
<?php
$pageChild = get_pages( array( 'child_of' => $post->ID, 'sort_column' => 'menu_order', 'sort_order' => 'ASC' ) );
foreach( $pageChild as $page ) {
?>
<!-- loop: child page -->
<div class="child">
<header class="entry-header">
<?php echo '<h3>'.$page->post_title.'</h3>'; ?>
</header><!-- .entry-header -->
<img src="<?php echo the_post_thumbnail_url( $page->ID ); ?>">
<?php echo $page->the_excerpt; ?>
</div>
<?php } ?>
</div>
So far, I can see the links/titles of the correct child-pages, and in the correct order, but not the Thumbnail or Excerpt. Obviously, I am not calling the Thumbnail or the Excerpt properly. Could someone please correct me?
I have also tried these lines, as supported by the twenty-sixteen theme:
<?php twentysixteen_post_thumbnail(); ?>
<?php the_excerpt(); ?>
Any help would be much appreciated!

Answer 1

The thumbnail doesn't show because the function the_post_thumbnail_url(); shows the thumbnail of the current post, the parameter is to specify the size of the image, not the post.
$post->the_excerpt is not necessarily filled. If you look at the add/edit post screen you'll notice two textfields, one for editing the content of the post and one for the excerpt. The excerpt is optional, so the function the_excerpt() shows the content of that field, but when it is empty it will show the first X characters of $post->the_content.
Regarding your second attempt: the functions the_excerpt(), get_permalink() and twentysixteen_post_thumbnail() don't work because you don't set up the post properly.
The easiest way would be to add setup_postdata() to your code:
$pageChild = get_pages( array( 'child_of' => $post->ID, 'sort_column' => 'menu_order', 'sort_order' => 'ASC' ) );
foreach( $pageChild as $page ) {
setup_postdata( $page );
// now you can use all the fancy functions like `the_excerpt()`
// add your output here
}
Or you can do it the recommended way, using a WP_Query object:
<?php
$args = array(
'post_parent' => $post->ID,
'orderby' => 'menu_order',
'order' => 'ASC'
);
$the_query = new WP_Query( $args ); ?>
<?php if ( $the_query->have_posts() ) : ?>
<!-- pagination here -->
<!-- the loop -->
<?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>
<h2><?php the_title(); ?></h2>
<?php endwhile; ?>
<!-- end of the loop -->
<!-- pagination here -->
<?php wp_reset_postdata(); ?>
<?php else : ?>
<p><?php _e( 'Sorry, no posts matched your criteria.' ); ?></p>
<?php endif; ?>