Question

我对函数进行了AJAX调用：

$('#DeviceType').change(function () {
   // when the selection of the device type drop down changes 
   // get the new value
   var devicetype = $(this).val();

   $.ajax({
      url: '@Url.Action("GetEquipmentCode")',
      type: 'POST',
      data: { deviceTypeID: devicetype },
      success: function (result) {
         // when the AJAX succeeds refresh the EquipmentCode text box
         $('#EquipmentCode').val(result);
      }
   });
});

功能为

[HttpPost]
public string GetEquipmentCode(int deviceTypeID)
{
   var deviceType = _db.DeviceTypes.Single(d => d.ID == deviceTypeID);

   return (deviceType.EquipmentCode != null) ? 
                      deviceType.EquipmentCode.Code : 
                      String.Empty;
}

但是，如果函数返回String.Empty，我在文本框中实际得到的字符串是“[object XMLDocument]”。如何在文本框中获得空字符串的结果？

Answer 1

尝试

  .... 
  data: { deviceTypeID: devicetype },
  dataType : 'html',
  ...

默认情况下，jquery尝试猜测，有时可能不准确。

More info here

Answer 2

JSON可能是最简单的。

尝试：

$('#DeviceType').change(function () {
   // when the selection of the device type drop down changes 
   // get the new value
   var devicetype = $(this).val();

   $.ajax({
      url: '@Url.Action("GetEquipmentCode")',
      type: 'POST',
      contentType: 'application/json; charset=utf-8',
      data: { deviceTypeID: devicetype },
      success: function (result) {
         // when the AJAX succeeds refresh the EquipmentCode text box
         $('#EquipmentCode').val(result);
      }
   });
});

然后在你的ActionMethod

中

[HttpPost]
public ActionResult GetEquipmentCode(int deviceTypeID)
{
   var deviceType = _db.DeviceTypes.Single(d => d.ID == deviceTypeID);

   return Json((deviceType.EquipmentCode != null) ? 
                      deviceType.EquipmentCode.Code : 
                      String.Empty);
}

将空字符串返回给AJAX请求

2 个答案: