Make a wordpress 404 page dynamic - wordpress

Question

So I cant find and info about this, but I want to hook the default 404 page to a page thru a custom page template so that I can manage the content on the 404 page. Is this possible ?

Answer 1

To do this, simply create a page named 404.php in your theme.
Take a look at the simple structure of the 404.php file that is shipped with Twenty Thirteen. It basically features tags that display the header, sidebar, and footer, and also an area for your message:
<div id="primary" class="content-area">
<div id="content" class="site-content" role="main">
<header class="page-header">
<h1 class="page-title"><?php _e( 'Not Found', 'twentythirteen' ); ?></h1>
</header>
<div class="page-wrapper">
<div class="page-content">
<h2><?php _e( 'This is somewhat embarrassing, isn’t it?', 'twentythirteen' ); ?></h2>
<p><?php _e( 'It looks like nothing was found at this location. Maybe try a search?', 'twentythirteen' ); ?></p>
<?php get_search_form(); ?>
</div><!-- .page-content -->
</div><!-- .page-wrapper -->
</div><!-- #content -->
</div><!-- #primary -->
So, to change the error message your visitor sees, revise the text within the h1 heading and within the page-content class; if necessary, add more paragraphs below that.
You can see more about this in the WordPress Codex.
Now to add content to this page you'll need to first create a new page in WP and tell it to use your 404 template. Once we've added page content we just need to add some code to the template php file. The following assumes that our new page has an ID of '12'.
<?php
// would get post 12's entire content after which you
// can manipulate it with your own trimming preferences
$post_12 = get_post(12);
$content = $post_12->post_content; //would echo post 12's content
//$excerpt = $post_12->post_excerpt; // would echo post 12's content up until the <!--more--> tag
?>
Now add this code into your template like so:
<?php
/**
* The template for displaying 404 pages (Not Found)
*
* #package WordPress
* #subpackage Twenty_Thirteen
* #since Twenty Thirteen 1.0
*/
get_header(); ?>
$post_12 = get_post(12);
$content = $post_12->post_content; //would echo post 12's content
<div id="primary" class="content-area">
<div id="content" class="site-content" role="main">
<header class="page-header">
<h1 class="page-title"><?php _e( 'Not Found', 'twentythirteen' ); ?></h1>
</header>
<div class="page-wrapper">
<div class="page-content">
<h2><?php $content ?></h2>
<p><?php _e( 'It looks like nothing was found at this location. Maybe try a search?', 'twentythirteen' ); ?></p>
<?php get_search_form(); ?>
</div><!-- .page-content -->
</div><!-- .page-wrapper -->
</div><!-- #content -->
</div><!-- #primary -->
<?php get_footer(); ?>
However, assuming that you want to install this on a system where you don't know the page ID you could always create a page via your theme or plugin that uses a fixed name/title, eg: "custom-404".
Then you can change your template's code to call that post by name/title, since we always know what this is called.
$page = get_page_by_title( 'custom-404' );
//$post_12 = get_post(12);
$content = $page->post_content; //would echo post custom-404's content