<?php // add custom post meta media_url for posts function themename_media_url_meta() { add_meta_box( 'themename_meta', 'Media embed URL', 'themename_media_url_meta_html', 'post', 'side', 'default' ); } add_action( 'add_meta_boxes', 'themename_media_url_meta' ); function themename_media_url_meta_html( $post ) { $themename_media_url = get_post_meta( $post->ID, '_themename_media_url', true); ?> <input type="text" class="widefat" name="themename_media_url" value="<?php echo esc_attr( $themename_media_url ); ?>" /> <?php } function themename_save_project_meta( $post_ID ) { global $post; if( $post->post_type == "post" ) { if( isset( $_POST ) ) { update_post_meta( $post_ID, '_themename_media_url', strip_tags( $_POST['themename_media_url'] ) ); } } } add_action( 'save_post', 'themename_save_project_meta' ); ?>