How to replace meta title and meta description in wordpress?

2 comments

1. How document title is generated has changed since WordPress v4.4.0. Now wp_get_document_title dictates how title is generated:

   /**
    * Displays title tag with content.
    *
    * @ignore
    * @since 4.1.0
    * @since 4.4.0 Improved title output replaced `wp_title()`.
    * @access private
    */
   function _wp_render_title_tag() {
       if ( ! current_theme_supports( 'title-tag' ) ) {
           return;
       }
   
       echo '<title>' . wp_get_document_title() . '</title>' . "n";
   }
   

   Here is the code from v5.4.2. Here are the filters you can use to manipulate title tag:

   function wp_get_document_title() {
       /**
       * Filters the document title before it is generated.
       *
       * Passing a non-empty value will short-circuit wp_get_document_title(),
       * returning that value instead.
       *
       * @since 4.4.0
       *
       * @param string $title The document title. Default empty string.
       */
       $title = apply_filters( 'pre_get_document_title', '' );
       if ( ! empty( $title ) ) {
           return $title;
       }
       // --- snipped ---
       /**
       * Filters the separator for the document title.
       *
       * @since 4.4.0
       *
       * @param string $sep Document title separator. Default '-'.
       */
       $sep = apply_filters( 'document_title_separator', '-' );
   
       /**
       * Filters the parts of the document title.
       *
       * @since 4.4.0
       *
       * @param array $title {
       *     The document title parts.
       *
       *     @type string $title   Title of the viewed page.
       *     @type string $page    Optional. Page number if paginated.
       *     @type string $tagline Optional. Site description when on home page.
       *     @type string $site    Optional. Site title when not on home page.
       * }
       */
       $title = apply_filters( 'document_title_parts', $title );
       // --- snipped ---
       return $title;
   }
   

   So here are two ways you can do it.

   First one uses pre_get_document_title filter which short-circuits the title generation and hence more performant if you are not going make changes on current title:

   function custom_document_title( $title ) {
       return 'Here is the new title';
   }
   add_filter( 'pre_get_document_title', 'custom_document_title', 10 );
   

   Second way uses document_title_separator and document_title_parts hooks for the title and the title seperator that are executed later in the function, after title is generated using functions like single_term_title or post_type_archive_title depending on the page and about to be outputted:

   // Custom function should return a string
   function custom_seperator( $sep ) {
      return '>';
   }
   add_filter( 'document_title_separator', 'custom_seperator', 10 );
   
   // Custom function should return an array
   function custom_html_title( $title ) {
      return array(
        'title' => 'Custom Title',
        'site'  => 'Custom Site'
       );
   }
   add_filter( 'document_title_parts', 'custom_html_title', 10 );
   

2. For anybody coming to this question in the future: This functionality can be accomplished using the Yoast SEO plugin.

   However, if you do want to still do this yourself….

   In order to modify the title, rather than the wp_head hook, you need to be using the filters that actually allow you to modify the title: wp_title

   And you can / should use the wp_head in order to add the meta description (see the docs here: http://codex.wordpress.org/Meta_Tags_in_WordPress)

   Also note there’s easier ways to get the page title, mentioned below…

   For the title, your code would look something like so:

   function changeTitle($title, $sep, $seplocation){
       global $wpdb;
   
       // NOTE: This is the HARD way to get the page title, and is unreliable...
       $cur_url = $_SERVER['REQUEST_URI']; 
       $basename = pathinfo($cur_url);
       $ebasename = $basename['filename'];
   
       if(is_numeric($ebasename)) {
           $url = explode('/', $basename['dirname']);
           $basename = explode('.', $url[count($url)-2]);
           $ebasename = $basename[0];
       }
   
       $pageName = $ebasename;
   
       // NOTE: Why not get pagename this way?
       global $post;
       $pageName = $post->post_title;
   
       // or if you need the slug...
       $pageName = $post->post_slug;
   
       $arraylist_subcat  = array("car","bike","boat","xxxx","yyyy","zzz","mmmm");
       $arraylist_maincat = array("aus","ind","usa","uae");
   
   
       $category_id = get_term_by('slug',$pageName, 'category');   
       $category_parentid  = get_term_by('id', $category_id->parent, 'category');   
       $parent_slug =  $category_parentid->slug;
   
   
   
      if ( is_page()) {        
           if ( in_array($pageName,$arraylist_maincat) ) {         
                   $title = 'Browse  '.$pageName.' | Some txt title | mysite.com';                 
           }
       }
   
       return $title;
   }
   
   add_action( 'wp_title', 'changeTitle', 10, 3 );
   

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