[Wordpress] Add metabox and custom column

funtions.php

<?php 
/**
 * Custom metabox to change priority displaying courses
 * ====================================================
 */
add_action( 'add_meta_boxes', 'tj_amb_priority_courses' );
function tj_amb_priority_courses() {
  add_meta_box( 'tj_mb_priority_courses', 'Display Priority', 'tj_mb_priority_courses_cb', 'sfwd-courses', 'side', 'high' );
}

function tj_mb_priority_courses_cb($post) {
  wp_nonce_field( 'tj_mb_priority_courses_nonce', 'mb_priority_courses_nonce' );
  $val = get_post_meta( $post->ID, 'sfwd-display-priority', true );
  ?>
  <div class="sfwd_input" id="sfwd-display-priority">
   <span class="sfwd_option_label" style="text-align:right;vertical-align:top;">
     <a class="sfwd_help_text_link" style="cursor:pointer;" title="Click for Help!" onclick="toggleVisibility('sfwd-display_priority_tip');">
       <img src="<?php echo get_template_directory_uri(); ?>/assets/img/question.png">
       <label class="sfwd_label textinput">
         Display Priority
       </label>
     </a>
   </span>
   <span class="sfwd_option_input">
     <div class="sfwd_option_div">
       <input name="sfwd-display-priority" type="number" value="<?php echo $val; ?>" style="width:70%;">
     </div>
     <div class="sfwd_help_text_div" style="display:none" id="sfwd-display_priority_tip">
       <label class="sfwd_help_text">
         Enter the ordered number to be displayed.<br>
         Smaller value will appear at the top.
       </label>
     </div>
   </span>
   <p style="clear:left">
   </p>
 </div>
 <?php
}

add_action( 'save_post', 'tj_mb_save_priority_courses' );
function tj_mb_save_priority_courses( $post_id ) { 
  if( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return; 
  if( !isset( $_POST['meta_box_nonce'] ) || !wp_verify_nonce( $_POST['mb_priority_courses_nonce'], 'tj_mb_priority_courses_nonce' ) ) return;
  if( !current_user_can( 'edit_post' ) ) return;

  // Make sure your data is set before trying to save it
  if( isset( $_POST['sfwd-display-priority'] ) )
    update_post_meta( $post_id, 'sfwd-display-priority', $_POST['sfwd-display-priority'] );

}

/**
 * Add priority to column on view all course
 */
add_filter( 'manage_edit-sfwd-courses_columns', 'tj_sfwd_courses_columns' ) ;
function tj_sfwd_courses_columns( $columns ) {

  $columns = array(
    'cb' => '<input type="checkbox" />',
    'title' => __( 'Title' ),
    'categories' => __( 'Categories' ),
    'tags' => __( 'Tags' ),
    'comments' => __( 'Comments' ),
    'priority' => __( 'Priority' ),
    'date' => __( 'Date' ),
  );

  return $columns;
}

add_action( 'manage_sfwd-courses_posts_custom_column', 'tj_manage_sfwd_courses_columns', 10, 2 );
function tj_manage_sfwd_courses_columns( $column, $post_id ) {
  global $post;

  switch( $column ) {

    /* If displaying the 'priority' column. */
    case 'priority' :

      /* Get the priority for the post. */
      $terms = get_post_meta( $post_id, 'sfwd-display-priority', true );

      /* If terms were found. */
      if ( !empty( $terms ) ) {

        echo $terms;
      }

      /* If no terms were found, output a default message. */
      else {
        _e( 'No Priority' );
      }

      break;

    /* Just break out of the switch statement for everything else. */
    default :
      break;
  }
}

/* Enable sortable for priority column */
add_filter( 'manage_edit-sfwd-courses_sortable_columns', 'tj_sfwd_courses_sortable_columns' );
function tj_sfwd_courses_sortable_columns( $columns ) {

  $columns['priority'] = 'priority';

  return $columns;
}

/* Only run our customization on the 'edit.php' page in the admin. */
add_action( 'load-edit.php', 'tj_edit_sfwd_courses_load' );

function tj_edit_sfwd_courses_load() {
  add_filter( 'request', 'tj_sort_priority' );
}

/* Sorts the priority. */
function tj_sort_priority( $vars ) {

  /* Check if we're viewing the 'sfwd-courses' post type. */
  if ( isset( $vars['post_type'] ) && 'sfwd-courses' == $vars['post_type'] ) {

    /* Check if 'orderby' is set to 'priority'. */
    if ( isset( $vars['orderby'] ) && 'priority' == $vars['orderby'] ) {

      /* Merge the query vars with our custom variables. */
      $vars = array_merge(
        $vars,
        array(
          'meta_key' => 'sfwd-display-priority',
          'orderby' => 'meta_value_num'
        )
      );
    }
  }

  return $vars;
}
?>