Validating post title and content in WordPress

3 comments

1. This code makes sure that post title is not empty or longer than 100 characters. You can adjust it to your needs if necessary. The code will work as follows:

   • If errors occur while you are creating a new post, the post won’t be published and it will remain in auto-draft status (it won’t show in the listing);
   • If errors occur during the update of the existing post, the post_title and post_status will not be changed;
   • Replace your_custom_post_type with your custom post type.

   The code:

   <?php
   
   add_action('save_post_{your_custom_post_type}', 'custom_validate_post', 10, 2);
   
   if (!function_exists('custom_validate_post')) {
       function custom_validate_post(int $post_ID, WP_Post $post): void
       {
           // Exit early if save_post is triggered when trashing the post
           if ($post->post_status === 'trash' || defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
               return;
           }
   
           $errors = [];
   
           // Validation filters
           if (empty($post->post_title)) {
               $errors['title'] = 'The title is required';
           }
   
           if(strlen($post->post_title) > 100) {
               $errors['title'] = 'The title should not be longer than 100 characters';
           }
   
           // If we have errors lets setup some messages
           if (!empty($errors)) {
               // Save the errors as option
               update_option('post_errors', $errors);
   
               // admin_notice is create by a $_GET['message'] with a number that wordpress uses to
               // Display the admin message so we will add a filter for replacing default admin message with a redirect
               add_filter('redirect_post_location', function (string $location) {
                   // Remove $_GET['message']
                   $location = remove_query_arg( 'message', $location );
   
                   // Add our new query sting
                   $location = add_query_arg( 'custom_validation', 'failed', $location );
   
                   // Return the location query string
                   return $location;
               });
           }
       }
   }
   
   // We use this action to get the data before and after the update in order to revert the data if validation fails
   add_action('post_updated', 'custom_set_old_post_data_if_error', 10, 3);
   
   if (!function_exists('custom_set_old_post_data_if_error')) {
       function custom_set_old_post_data_if_error(int $post_ID, WP_Post $post_after, WP_Post $post_before)
       {
           // Exit early if post_updated is triggered when trashing the post
           if ($post_after->post_status === 'trash' || $post_after->post_type !== 'your_custom_post_type') {
               return;
           }
   
           if (empty($post_after->post_title) || strlen($post_after->post_title) > 100) {
               // We must remove this action or it will loop forever since we use wp_update_post below
               remove_action('post_updated', 'custom_set_old_post_data_if_error');
   
   
               // Set old `post_title` and `post_status` if validation fails
               wp_update_post(
                   [
                       'ID' => $post_after->ID,
                       'post_title' => $post_before->post_title,
                       'post_status' => $post_before->post_status,
                   ]
               );
   
               add_action('post_updated', 'custom_set_old_post_data_if_error');
           }
       }
   }
   
   // Add new admin message
   add_action( 'admin_notices', function () {
           if (isset($_GET['custom_validation']) && $_GET['custom_validation'] === 'failed') {
   
           // Get the errors from the option album_errors
           $errors = get_option('post_errors');
   
           // Now delete the option post errors
           delete_option('post_errors');
   
           $display = '<div id="notice" class="error"><ul>';
   
           // Because we are storing as an array we should loop through them
           foreach ( $errors as $error ) {
               $display .= '<li>' . $error . '</li>';
           }
   
           $display .= '</ul></div>';
   
           // Finally echo out our display
           echo $display;
   
           // Add some jQuery
           ?>
           <script>
               jQuery(function($) {
                   $("#title").css({"border": "1px solid red"})
               });
           </script>
           <?php
       }
   });
   

   There are couple of things to be aware of:

   • if there are posts in trash with the title that is not valid, you won’t be able to untrash these posts before changing the title;
   • if you want to apply this to all of the posts and not a certain custom post type, use save_post hook instead of save_post_{your_custom_post_type} and remove $post_after->post_type !== 'your_custom_post_type' condition from the code.

   Wish you best of luck!

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2. Try this:

   Use plugin for that. It will help you needful.

   Refer this: http://wordpress.org/plugins/post-title-validation/

   OR

   Use this code.

   add_action( 'admin_notices', 'custom_error_notice' );
   function custom_error_notice(){
       global $current_screen, $post;
       if ( $current_screen->parent_base == 'edit' ){
           if((!$post->post_name && !$post_content) && $_GET['post']) {
               wp_redirect(admin_url('post-new.php?empty=1'));
           }
           if($_GET['empty']) echo '<div class="error"><p>Warning - Please fill up all fields correctly!</p></div>';
       }
   }
   

   • Thanks

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3. The hook needed is wp_insert_post_data

   http://codex.wordpress.org/Plugin_API/Filter_Reference/wp_insert_post_data

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