A check for if is parent page, if has children, if has grandchildren

Question

I have one default page template that I wish to use for two scenarios. I'd prefer to use only one page template for the sake of simplicity for my client.

Here's what I'm trying to accomplish:

if parent_page OR if child-page without children {
  display full-width-layout
}
if child page with children or if grandchild page {
  display sidebar-menu-layout
}

Is this possible?

This is what I've tried so far:

if( is_page() && $post->post_parent > 0 ) {
  //display sidebar-menu-layout
} else {
  //display full-width-layout
}

It works so far as on top level pages, it displays full-width-layouts. But, what can I do to make sure that the sidebar-menu-layout is displayed on child-pages with children and on grandchile pages only? And for child-pages with no children, to display the full-width-layout.

Thanks in advance. I'm sure it has a simple solution, I'm just relatively new to WP so still trying to figure out what can and cannot be done.

Answer 1

Before reading the solution Bravokeyl provided I had finally, through trial and error, come up with a solution that worked for me. I'm not sure which is the better of the two, or the most correct, I only know that mine worked for me, for the problem I had.

This is the code I used to display full-width layout or sidebar-menu layout:

if( is_page() && $post->post_parent > 0 ) { 
  // post has parents

  $children = get_pages('child_of='.$post->ID);
  if( count( $children ) != 0 ) {
    // display sidebar-menu layout
  }

  $parent = get_post_ancestors($post->ID);
  if( count( $children ) <= 0  && empty($parent[1]) ) {
    // display full-width layout
  } elseif ( count( $children ) <= 0  && !empty($parent[1]) )  {
    // display sidebar-menu layout
  }

} else {
  // post has no parents
  // display full-width layout
}

Answer 2

Level-0
--Level-1
----Level-2
------Level-3
----Levelanother-2
--Levelanother-1

check whether page is top level page (it may have children or not) ?

$post->$post_parent == 0 or is empty get_post_ancestors( $post ) returns only Level-0 Pages.

Is a child page and is a Level-1 page or Levelanother-1 only ?

$post->$post_parent > 0 or is not empty get_post_ancestors( $post ) and is empty get_post_ancestors( $post->post_parent )

Is level-1 page but doesn't have children like Levelanother-1 page ?

$post->$post_parent > 0 or is not empty get_post_ancestors( $post ) and is empty get_post_ancestors( $post->post_parent ) and count(get_children( $post ->ID, 'ARRAY_A' )) == 0 ..

I didn't check this yet..but it should work fine. You can also play with get_page_children() and get_posts()