从Javascript调用Web服务时使用文档对象而不是JSON

Question

I am running an Ajax call from javascript to a webservice:

 $.ajax(signingURI + "?fileName=" + fileName)
        .done(function (data){
  });

My webservice:

 [WebMethod]
 public string PolicyGenerator(string fileName){
       return "{\"res\":\"asdasda\"}" ;
 }

When inspecting the data argument I get a XML document object instead of JSON . What I am doing wrong?

In the watch expression:

data: document
URL: ""
anchors: HTMLCollection[0]
applets: HTMLCollection[0]
baseURI: null
body: null
characterSet: null
charset: undefined
childNodes: NodeList[1]
compatMode: "CSS1Compat"
constructor: DocumentConstructor
cookie: [Exception: DOMException]
defaultCharset: undefined
defaultView: null
......

Answer 1

If you want to use HTTP GET, decorate your webservice method with ScriptMethod .

[WebMethod]
[ScriptMethod(UseHttpGet = true)]
public string PolicyGenerator(string fileName){
      return "{\"res\":\"asdasda\"}" ;
}

Also, don't manually construct JSON on either end of your transaction. jQuery serializes objects for you.

$.ajax({
    ...
    data: { fileName: 'test.jpg' }
});

With GET requests, the data will be serialized onto a query string. With POST, it is sent in the request entity body in standard x-www-form-urlencoded style. If you want to send JSON in the POST body, use JSON.stringify .

Your server-side function should return a serializable class. .NET will output proper JSON for you.

[WebMethod]
[ScriptMethod(UseHttpGet = true)]
public PolicyGeneratorResponse PolicyGenerator(string fileName){
      return new PolicyGeneratorResponse(...);
}

...

class PolicyGeneratorResponse {
    public string res;
}

Answer 2

Try adding a dataType to the request:

$.ajax(signingURI + "?fileName=" + fileName, { dataType: 'json' })
        .done(function (data){
});

Answer 3

Something is very weird going on. Seems that the webservice does return JSON, but when I used the .done callback I couldn't read it.

$.ajax({
         type: "POST",
         url: signingURI,
         data: "{'fileName':'" + encodeURI('test.jpg') + "'}",
         contentType: "application/json; charset=utf-8",
         dataType: "json",
         success: function(msg){

Using the success callback inside the other properties gave me JSON. So weird, or is it?.