Custom Canonical URLs

Question

I am moving my site from olddomain.com to newdomain.com. I want to keep all of the content at olddomain.com but I want the canonical version in google to be recognized as newdomain.com/whatever-post/ instead of the same thing at olddomain.com.

How can I modify the rel=canonical in the section of olddomain.com to make this change?

Answer 1

Unfortunately, there's no filter in the rel_canonical() function. But you can remove that function from wp_head altogether and write your own. Try adding this to the functions.php at your old domain:

remove_action( 'wp_head', 'rel_canonical' );
add_action( 'wp_head', 'new_rel_canonical' );

function new_rel_canonical() {
     if ( !is_singular() )
          return;

      global $wp_the_query;
      if ( !$id = $wp_the_query->get_queried_object_id() )
          return;

      $link = get_permalink( $id );
      $link = str_replace( 'olddomain.com', 'newdomain.com', $link );
      echo "<link rel='canonical' href='$link' />\n";
  }

Obviously, just replace olddomain.com and newdomain.com in the second to last line with your actual domain names!