Unable to send JSON data to MVC controller

Question

I have a JavaScript function that looks as follows:

function exportToExcel() {
    $.ajax({
        url: "/eBird/ExportToExcel",
        data: jsonSightingData,
        type: 'POST',
        contentType: 'application/json'
    });
}

My MVC controller looks like this:

    public ActionResult ExportToExcel(List<Entities.MyClass> data)
{
    try
    {
        ...
    }
    catch (System.Exception exception)
    {
       ...
    }

MyClass defintion is:

   public class MyClass
    {
        public string comName { get; set; }
        public int howMany { get; set; }
        public double lat { get; set; }
        public double lng { get; set; }
        public string locID { get; set; }
        public string locName { get; set; }
        public bool locationPrivate { get; set; }
        public string obsDt { get; set; }
        public bool obsReviewed { get; set; }
        public bool obsValid { get; set; }
        public string sciName { get; set; }
    }

The class matches the JSON data coming in exactly. The problem is that when my controller method is called, 'data' is always NULL. My understanding was that the MVC model binder would automatically bind the JSON data to my MyClass list. But it doesn't appear to be working.

Sample JSON is as follows:

[{"comName":"Great Black-backed Gull","lat":42.4613266,"lng":-76.5059255,"locID":"L99381","locName":"Stewart Park","locationPrivate":false,"obsDt":"2014-09-19 12:40","obsReviewed":false,"obsValid":true,"sciName":"Larus marinus"}]

When you look at `ModelState` in the controller action do you see any errors? — Andrew Whitaker, Sep 20 '14 at 00:44
@StephenMuecke - Tried that, but now my MVC controller method is never getting called. No JavaScript error either. — Randy Minder, Sep 20 '14 at 01:24
Strange - copied your code to my project. With `data: jsonSightingData,` I get Internal Server Error`, With `data: JSON.stringify(jsonSightingData),` it populates correctly. — , Sep 20 '14 at 01:31
@Randy, I've Had the same issue, I used "object" as I mentioned in my answer to catch it (instead of the List, than I was able to see what was wrong - in my case unicode. but anyway - once you get the object in your controller you can use another de-serializer to do what need to be done.... — Dani, Sep 20 '14 at 03:13

score 0 · Accepted Answer · edited May 23 '17 at 12:29

Use a General Object (Like JContainer) to "capture" the incoming data. or even Object if you are not sure what you get. Then see what you have inside. I use an external deserializer to convert json back to class. (using .ToString() to make it readable to the serializer)

(try Json.Net)

Also - make sure that the JSON is not converted into Unicode. I've had an issue with that as well.

another remark - I think content type should be application/json. Read this: SO about json content type

score -1 · Answer 2 · answered Sep 20 '14 at 01:29

Run Fiddler and capture Json sent to controller. The controller expects a List but looks like you are sending single object. Stuff coming in as null happens to many of us. I'll try and run what you have. Can you also mess with controller and give it just MyClass coming in?

Unable to send JSON data to MVC controller

2 Answers2