Display Parent Page Title and Child Page Title and Content - wordpress

Question

I have a custom post type with page attributes so I can create sub pages. I'm trying to display the title of the parent page in the h1 and then have it loop through and display the content of the child pages. The code below almost does this but it's outputting the child pages also in the first bit as h1 titles so I'm getting duplicates of the child page titles. How can I exclude the child pages and prevent them from displaying in the first part of the loop?
Many thanks.
<?php
echo "<ul>";
if ( have_posts() ) {
while ( have_posts() ) {
the_post();
echo "<li><h1>".get_the_title()."</h1>";
$args=array(
'orderby' => 'menu_order',
'order' => 'ASC',
'post_parent' => $post->ID,
'post_type' => get_post_type( $post->ID ),
'posts_per_page' => 10
);
$childpages = new WP_Query($args);
if($childpages->post_count > 0) { /* display the children content */
echo "<ul>";
while ($childpages->have_posts()) {
$childpages->the_post();
echo "<li><h2>".get_the_title()."</h2></li>";
echo "<li><h2>".the_content()."</h2></li>";
}
echo "</ul>";
}
wp_reset_query();
echo "</li>";
}
}
echo "</ul>";
?>
Update: Managed to get a little bit further, almost there I think. I can now see just one sub post (the latest) and the same sub post is duplicated under each parent title either though it isn't a child of the others.
Can anyone please help me nail this last bit. Thanks.
<?php $parent_pages = get_pages( array(
'parent' => 0,
'post_type'=> 'archive'
));
foreach( $parent_pages as $parent_pages)
{ ?>
<h1><?php echo $parent_pages->post_title; ?></h1>
<?php
$children = get_pages(array(
'orderby' => 'menu_order',
'order' => 'ASC',
'post_parent' => $post->ID,
'post_type' => get_post_type( $post->ID )
));
foreach($children as $child);
?>
<h2><?php the_title(); ?></h2>
<?php the_content(); ?>
<?php } ?>
Update: Trying #robbintt suggestions, I'm now here. Not sure if I'm using the get_page_children correctly and I'm now getting "Parse error: syntax error, unexpected T_AS, expecting ';' "
<?php
$parent_pages = get_pages( array(
'parent' => 0,
'post_type'=> 'archive'
) );
for ( $parent_pages as $parent_page { ?>
<h1><?php echo $parent_page->post_title; ?></h1>
<?php
$all_pages = get_pages()
$child_pages = get_page_children($parent_pages->ID, $all_pages );
for ( $child_pages as $child_page ) { ?>
<h2><?php echo $child_page->post_title; ?></h2>
<p><?php echo $child_page->post_content; ?></p>
<?php } ?>
Update: Here's my final working code thanks to #robbintt for the help.
<?php
$parent_pages = get_pages( array( 'parent' => 0, 'post_type'=> 'archive' ) );
foreach ( $parent_pages as $parent_page ) {
echo '<h1>';
echo $parent_page->post_title;
echo '</h1>';
$all_pages = get_pages(array( 'post_type'=> 'archive' ) );
$child_pages = get_page_children($parent_page->ID, $all_pages );
foreach ( $child_pages as $child_page ) {
echo '<h2>';
echo $child_page->post_title;
echo '</h2>';
echo '<p>';
echo $child_page->post_content;
echo '</p>';
}
}
?>

Answer 1

You're abusing the loop a little bit here by using the standard while ( have_posts() ) {}.
Instead, lets target the parent page, and then use a for loop to get the child pages.
/* here we include only pages with no parent */
$parent_pages = get_pages( 'parent' => 0 )
foreach ( $parent_pages as $parent_page ) {
/* Proceed as you have inside the while loop, targeting $parent_page each time */
}
Here is the rest of the documentation so you can sort as you wish: http://codex.wordpress.org/Function_Reference/get_pages#Parameters
Part 2:
Here's the next requested section, how to get information for child pages:
http://codex.wordpress.org/Function_Reference/get_page_children
This function will return an array of page children. The key here is that this loop is run inside the other loop which actually gets all the parent pages.
$all_pages = get_pages( array( 'post_type'=> 'archive' ) )
$child_pages = get_page_children($parent_page->ID, $all_pages );
foreach ( $child_pages as $child_page ) {
/* proceed with any calls on child page such as ID/title, in the format $child_page->ID */
Let me know how it goes! Here's the new function we are using:
http://codex.wordpress.org/Function_Reference/get_page_children
Part Three:
Here I've cleaned up your code a bit for the child page section. There was a lot going on, so I standardized and simplified how you echo'd HTML and added a lot more lines. This made the design pattern a lot more visible to the human eye.
<?php
$parent_pages = get_pages( array( 'parent' => 0, 'post_type'=> 'archive' ) );
foreach ( $parent_pages as $parent_page ) {
echo '<h1>';
echo $parent_page->post_title;
echo '</h1>';
$all_pages = get_pages( array( 'post_type'=> 'archive' ) );
$child_pages = get_page_children($parent_page->ID, $all_pages );
foreach ( $child_pages as $child_page ) {
echo '<h2>';
echo $child_page->post_title;
echo '</h2>';
echo '<p>';
echo $child_page->post_content;
echo '</p>';
}
}
?>
Here's my original writeup of this code: http://codepad.org/pLtFCI1l