wcf service json 400 Bad Request - ajax

Question

I get a 400 Bad Request error when I try to call WCF service from client side using ajax. Following is my code,
[OperationContract]
[WebInvoke(Method = "POST",
BodyStyle = WebMessageBodyStyle.Wrapped,
ResponseFormat = WebMessageFormat.Json)]
string[] GetUser(string Id);
$.ajax({
type: "POST", //GET or POST or PUT or DELETE verb
url: "http://localhost:58055/Service1.svc/GetUser",
crossDomain: true,
data: '{"Id": "3"}',
contentType: "application/json; charset=utf-8",
dataType: "json", //Expected data format from server
processdata: true, //True or False
success: function (msg) {//On Successfull service call
alert(msg.GetUserResult[0]);
console.log("success " + msg);
},
error: function (msg) {//On Successfull service call
console.log(msg);
}
});
Any insights would be really helpfull...

Answer 1

The first thing you should try is hit the URL using fiddler(so that you could post your data too) and see if you get the same error.
Are you making a cross domain request. From the example it looks like you are not. Could you remove
crossDomain: true,
line and try the jquery again.
There are other options also which unnecessay like processdata. Suggest you to use the following code and see if it works or not.
$.ajax({
type: "POST",
// the url to the service -
url: "url",
// the format that the data should be in when
// it is returned
contentType: "json",
data: '{"Id": "3"}',
// the function that executes when the server
// responds to this ajax request successfully
success: function(data) {
// put the JSON response in the employees table
}

Answer 2

According to the ajax api documentation the default content type is 'application/x-www-form-urlencoded'. When sending JSON, the content type should be 'application/json; charset=utf-8' except that WCF does not like that. I got the same error messages and when I removed the content type I stopped getting this error. By the way, I noticed that you set crossDomain to true, this other question is relevant to that option.