custom_type_field

<?php

//above here it's theme's code

add_action('init', 'coupon_register');

function coupon_register() {

    $labels = array(
        'name' => _x('Coupons', 'post type general name'),
        'singular_name' => _x('Coupon', 'post type singular name'),
        'add_new' => _x('Add New', 'coupon item'),
        'add_new_item' => __('Add New Coupon Item'),
        'edit_item' => __('Edit Coupon Item'),
        'new_item' => __('New Coupon Item'),
        'view_item' => __('View Coupon Item'),
        'search_items' => __('Search Coupon'),
        'not_found' =>  __('Nothing found'),
        'not_found_in_trash' => __('Nothing found in Trash'),
        'parent_item_colon' => ''
    );

    $args = array(
        'labels' => $labels,
        'public' => true,
        'publicly_queryable' => true,
        'show_ui' => true,
        'query_var' => true,
        'menu_icon' => get_stylesheet_directory_uri() . '/cuponeria.png',
        'rewrite' => true,
        'capability_type' => 'post',
        'hierarchical' => false,
        'menu_position' => null,
        'supports' => array('title','editor','thumbnail')
      );

    register_post_type( 'coupon' , $args );
    flush_rewrite_rules();
}

register_taxonomy("coupon_category", array("coupon"), array("hierarchical" => true, "label" => "Coupon_categories", "singular_label" => "Coupon_category", "rewrite" => true));
register_taxonomy("stores", array("coupon"), array("hierarchical" => true, "label" => "Stores", "singular_label" => "Store", "rewrite" => true));

add_action("admin_init", "admin_init");

function admin_init(){
  add_meta_box("basic_info", "Basic info about coupon", "basic_info", "coupon", "normal", "low");
}

function basic_info() {
  global $post;
  $custom = get_post_custom($post->ID);
  $discount_percentage = $custom["discount_percentage"][0];
  $expire_date = $custom["expire_date"][0];
  ?>
  <p><label>Discount percentage: </label><br />
  <input cols="50" name="discount_percentage" value = "<?php echo $discount_percentage; ?>"></p>
  <p><label>Expire at: </label><br />
  <input cols="50" name="expire_date" value = "<?php echo $expire_date; ?>"></p>
  <?php
}

add_action('save_post', 'save_details');

function save_details(){
  global $post;
  update_post_meta($post->ID, "discount_percentage", $_POST["discount_percentage"]);
  update_post_meta($post->ID, "expire_date", $_POST["expire_date"]);
}