ajax响应JavaScript中的文档对象

Question

I try make ajax request to server with two parameters and get from server string:

JavaScript:

function getLetterOfResponsibilityNote(selectedCountryCode, selectedIntendedUseType) {
    $.ajax({
        type: "POST",
        url: "/Admin/Applications/SelectLetterOfRespinsibilityNote",
        cache: false,
        data: { countryCode: selectedCountryCode, intendedUseType: selectedIntendedUseType },
        success: function(response) {
            if (response !== "") {
                alert("1");
            }
        }
    });
}

And mvc action:

[HttpPost]
public string SelectLetterOfRespinsibilityNote(string countryCode, string intendedUseType)
{
  var countryDetails = new List<ContryLetterOfResponsibility>
  {
    new ContryLetterOfResponsibility
  {
    CountryCode = countryCode,
      IntendedUseType = intendedUseType
  }
};

string xml = XmlSerializerUtil(countryDetails);
var country = _countryService.GetLetterOfResponsibilityNotesByCountryCodeList(xml).FirstOrDefault();

if (country != null)
{
  return country.LetterOfResponsibilityNote;
}

return string.Empty;
}

I get response object in javascript and verify its value. If its value not empty string, I get alert message. If server pass in JavaScript empty string, i get Document object in success action NOT EMPTY STRING. What is it?

Answer 1

The response from an ajax call is an object, not a string. To get your string, you need to use the responseText property. Try this:

if (response.responseText !== "")

If you are using jQuery, see this page for more details.

Answer 2

The success function is passed an argument whose type is either based on the datatype property sent to the .ajax call, or is inferred from the returned data. So, you may want to try explicitly setting datatype: "text" in the ajax object, which should force the response variable to be a string:

function getLetterOfResponsibilityNote(selectedCountryCode, selectedIntendedUseType) {
    $.ajax({
        datatype: "text", // <-- added
        type: "POST",
        url: "/Admin/Applications/SelectLetterOfRespinsibilityNote",
        cache: false,
        data: { countryCode: selectedCountryCode, intendedUseType: selectedIntendedUseType },
        success: function(response) {
            if (response !== "") {
                alert("1");
            }
        }
    });
}