Automatically remove repeated words in slug

Question

i am looking for a way to remove repeated words in wordpress slug.

let say my domain is 'example.com'

and i have a category named 'WordPress How To'

i have configured the permalinks to be 'example.com/wordpress-how-to/'

then i want to create a post with the title "How To Create A Child Theme In WordPress"

then the permalinks will automatically generate this..

'example.com/wordpress-how-to/how-to-create-a-child-theme-in-wordpress/'

since the words "wordpress,how,to" are repeated, how can i automatically remove those words when i insert the title.

i want the permalinks will autogenerate this...

'example.com/wordpress-how-to/create-a-child-theme-in/'

it's actually easy to just edit the permalinks by clicking the edit button.

but is there any functions.php code to make it autogenerated?

Answer 1

According to your example

'example.com/wordpress-how-to/how-to-create-a-child-theme-in-wordpress/'

search  = wordpress-how-to
subject = how-to-create-a-child-theme-in-wordpress/

this code removes all the words from the subject found in search term.

for more details check "Avoiding infinite loops" from save_post

 function modified_slug( $post_id ) {

     // If this is a revision, get real post ID
     if ( $parent_id = wp_is_post_revision( $post_id ) )
         $post_id = $parent_id;

      // Get default category ID from options
      $defaultcat = get_option( 'default_category' );

      // Check if this post is in default category
      if ( in_category( $defaultcat, $post_id ) ) {
         // unhook this function so it doesn't loop infinitely
         remove_action( 'save_post', 'modified_slug', 13, 2 );

         $post_url  =   get_permalink( $post_id );

         $filtered  =   array_filter( explode( '/', str_replace( home_url(), '', $post_url)));
         $search    =   explode('-', array_shift(array_values($filtered)) );
         $subject   =   end($filtered);
         $new_slug      =   trim( str_replace( $search, '', $subject ), '-' );

         // Update post
         $my_post = array(
             'ID'               =>  $post_id,
             'post_name'    =>  $new_slug
         );

         // Update the post into the database
         wp_update_post( $my_post );

         // re-hook this function
         add_action( 'save_post', 'modified_slug', 13, 2 );
     }
 }
 add_action( 'save_post', 'modified_slug', 13, 2 );

1. https://codex.wordpress.org/Plugin_API/Action_Reference/save_post
2. https://codex.wordpress.org/Function_Reference/wp_is_post_revision
3. https://codex.wordpress.org/Function_Reference/wp_update_post