selected( mixed $selected, mixed $current = true, bool $echo = true )

使用示例

• 示例1

  实例

  <!-- Testing the values with if() -->
  <select name="options[foo]">
  	<option value="1" <?php if ( $options['foo'] == 1 ) echo 'selected="selected"'; ?>>1</option>
  	<option value="2" <?php if ( $options['foo'] == 2 ) echo 'selected="selected"'; ?>>2</option>
  	<option value="3" <?php if ( $options['foo'] == 3 ) echo 'selected="selected"'; ?>>3</option>
  </select>
   
  <!-- Using selected() instead -->
  <select name="options[foo]">
  	<option value="1" <?php selected( $options['foo'], 1 ); ?>>1</option>
  	<option value="2" <?php selected( $options['foo'], 2 ); ?>>2</option>
  	<option value="3" <?php selected( $options['foo'], 3 ); ?>>3</option>
  </select>
  
  

• 示例2

  使用foreach循环选择

  /**
   * Demonstration uses all cpt posts in a dropdown field to select 
   * a featured listings to callback in a function
   */
  function wporg_wpselected_featured_listing_cb()
  {
  
      $post_type = 'wpselected_post';
      $options   = get_option( 'wpselected_lists' );
  
      // select(ed)_id will be a custom option outside of this function.
      $wpselected_select_id = $options['wpselected_featured_listing'];
  
      // Avoid ending up with no string value by setting a default value
      if ( '' === $wpselected_select_id ) {
          $wpselected_select_id = 0; 
      }
  
      /**
       * Sets up a list of cpt posts to do foreach with
       * @param $label string Optional
       */
      $post_type_object = get_post_type_object( $post_type );
      $label = $post_type_object->label;
      $posts = get_posts( array(
              'post_type'         => $post_type, 
              'post_status'       => 'publish', 
              'suppress_filters'  => false, 
              'posts_per_page'    => -1
      ) );
      ?>
      <label class="olmin"><?php esc_html_e( 'Listing at top home page.', 'wpselected' ); ?></label>
      <select name="wpselected_lists[wpselected_featured_listing]">
      <option value="0"><?php echo esc_html__( $label, 'wpselected' ); ?></option>
      <?php 
      /**
       * `selected` magic in use
       */
      foreach ( $posts as $post ) {
          echo '<option value="' . esc_attr( $post->ID ) . '"' 
               . selected( $wpselected_select_id, $post->ID, false ) . '>' 
               . esc_html__( $post->post_title, 'wpselected' ) . '</option>';   
      }
      echo '</select>';  
  } 

  理想情况下，您可以选择使用ob_start()和ob_get_clean()，以避免前端出现任何HTML故障。