title: How to set default values in woocommerce checkout
body: <p>I have just created a page with order review using the following code </p>
  
  <pre><code>&lt;form name="checkout" method="post" class="checkout woocommerce-checkout" action="&lt;?php echo esc_url( $get_checkout_url ); ?&gt;" enctype="multipart/form-data"&gt;
  &lt;h3 id="order_review_heading"&gt;&lt;?php _e( 'Your order', 'woocommerce' ); ?&gt;&lt;/h3&gt;
  
      &lt;?php do_action( 'woocommerce_checkout_before_order_review' ); ?&gt;
  
      &lt;div id="order_review" class="woocommerce-checkout-review-order"&gt;
          &lt;?php do_action( 'woocommerce_checkout_order_review' ); ?&gt;
      &lt;/div&gt;
  
      &lt;?php do_action( 'woocommerce_checkout_after_order_review' ); ?&gt;&lt;/div&gt;
      &lt;/form&gt;
      &lt;?php do_action( 'woocommerce_after_checkout_form', $checkout ); ?&gt;
        &lt;/div&gt;
  </code></pre>
  
  <p>I have set the default value in <code>function.php</code> as follow :</p>
  
  <pre><code>function overridefields($fields)
  {
      global $wpdb;
      session_start();
      //print_r($_SESSION);
      //$fields['billing']['billing_delivery_date'] = array('label'=&gt;'Delivery Date','Placeholder'=&gt;'Date','required'=&gt;'false','readonly'=&gt;'true');
      $select_r = $wpdb-&gt;get_results("select * from `register` where `userid`='18'");
      //print_r($select_r);
      $fields['billing']['billing_first_name']['default']=$_SESSION['f_name'];
      $fields['billing']['billing_last_name']['default']=$_SESSION['l_name'];
      $fields['billing']['billing_address_1']['default']=$_SESSION['address'];
      $fields['billing']['billing_address_2']['default']='';
      $fields['billing']['billing_city']['default']=$_SESSION['city'];
      //$fields['billing']['billing_state']['default']=$select_r[0]-&gt;state;
      $fields['billing']['billing_email']['default']=$_SESSION['email'];
      $fields['billing']['billing_phone']['default']=$_SESSION['phone'];
      $fields['billing']['billing_postcode']['default']=$_SESSION['pincode'];
      //$fields['billing']['billing_delivery_date']['default']=$_SESSION['delivdate'];
      return $fields;
  }
  add_filter('woocommerce_checkout_fields','overridefields');
  </code></pre>
  
  <p>but when I click on checkout button then i got the error</p>
  
  <p><code>
      Country is a required field.
      First Name is a required field.
      Last Name is a required field.
      Address is a required field.
      Town / City is a required field.
      State / County is a required field.
      Postcode / Zip is a required field.
      Email Address is a required field.
      Phone is a required field.
  </code></p>
  
  <p>How can I set default value in woocommerce checkout page</p>