Json contentType: breaks Jquery POST to MVC controller

Question

I'm was trying to fill in a description field when a drop-down was selected. I Got it working but I couldn't use a Json Content Type. This works

<script type="text/javascript">
    $(document).ready(function () {
        $("#ddl_id").change(function () {
            var test = $("#ddl_id").val();
            $.ajax({
                type: "POST",
                url: "<%= Url.Action("GetVal") %>",
                data: {id: test},
                //contentType: "text/plain",
                dataType: "json",
                success: function(result) {
                    $("#serial").val(result);
                },
                error: function(e) {
                    alert(e);
                }
            });
        });
    });

</script>

But when I uncomment the contentType: I get null returned to my controller. I've also tried

contentType: "application/json; charset=utf-8",

This is my controller

 [HttpPost]
    public JsonResult GetVal(string id)
    {.......

Why is it that when I have a contentType I get null passed? And what is the best way to encode Json data? I'm totally new at this and I couldn't find a straight forward explanation.

Matthew Flaschen · Accepted Answer · 2010-08-19 02:24:23Z

2

$.ajax({
      type: "POST",
      url: "<%= Url.Action("GetVal") %>",
      data: JSON.stringify({id: test}),
      contentType: "application/json",
      dataType: "json",
      success: function(result) {
          $("#serial").val(result);
      },
      error: function(e) {
          alert(e);
      }
});

One of the gotchas with this function is that specifying a JSON contentType does not actually cause jQuery to JSON-encode your request. You have to do so manually or it will be serialized to application/x-www-form-urlencoded.

You need json2 and/or native JSON.

edited Aug 19, 2010 at 2:24

answered Aug 19, 2010 at 2:19

Matthew Flaschen

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1 Comment

Peter Over a year ago

Thanks for the response but, I tired what you gave me and I still can't get Null in the controller. The post has {"ID":"string"} but it still shows null on the server side.

Steve Czetty · Accepted Answer · 2012-10-21 03:01:51Z

0

On the server side, use an object to get the parameters value. like :

public class sealed MyClass{
   public Int32 ID{get;set;}
   // other properties here...
}

in the action method use like

[HttpPost]
public ActionResult MyAction(MyClass mycls){
    // here your can get the property,like
    mycls.ID;
}

you can read read the MSDN blog: Introducing ASP.NET MVC 3 (Preview 1)

edited Oct 21, 2012 at 3:01

Steve Czetty

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answered Jun 21, 2012 at 6:12

billschen

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