ASP.NET MVC sends JSON data to a controller action

Question

I am trying to send some JSON data to my ASP.NET MVC3 controller action method, but it will not work no matter what I do.

Here is my ajax call (it uses the JSON.stringify method from json2.js ):

$.ajax({ url: '/Home/GetData', type: "POST", dataType: "json", contentType: "application/json; charset=utf-8;", data: JSON.stringify(filters_data), success: function (data) { alert(data); } }); 

The violinist shows the request as follows:

 POST http://localhost:51492/Home/GetData HTTP/1.1 Host: localhost:51492 Connection: keep-alive Content-Length: 171 Origin: http://localhost:51492 X-Requested-With: XMLHttpRequest User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.75 Safari/535.7 Content-Type: application/json; charset=UTF-8; Accept: application/json, text/javascript, */*; q=0.01 Referer: http://localhost:51492/ Accept-Encoding: gzip,deflate,sdch Accept-Language: en-GB,en-US;q=0.8,en;q=0.6 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 {"Filters":[{"Field":3,"Operator":0,"Values":["30.01.2012.","30.01.2012."]},{"Field":2,"Operator":0,"Values":["-1"]},{"Field":0,"Operator":0,"Values":["some-string"]}]} 

My C # code:

 [HttpPost] public string GetData(QueryFilters filters) { return "Ho ho ho and a bottle of rum."; } [Serializable] public enum Fields { A, B, C, D } [Serializable] public enum FilterOperator { Is, Between, GreaterOrEqual, } [Serializable] public class QueryFilter { public Fields Field { get; set; } public FilterOperator Operator { get; set; } public List<string> Values { get; set; } } [Serializable] public class QueryFilters { public List<QueryFilter> Filters { get; set; } } 

I added the following line to the Application_Start () method for global.asax.cs:

 ValueProviderFactories.Factories.Add(new JsonValueProviderFactory()); 

The breakpoint in the GetData action method hits, but the Filters property value is null. Any ideas?

One more note: I tried to pass a much simpler object: Person - the string Name and int Age properties, with the same result - it seems that automatic model binding does not work for me, but I do not know how to check it.

Answer 1

The problem is that your action argument is called filters , and inside your QueryFilters model you have a property called filters , which confuses the standard mediator.

So just rename your action argument:

 [HttpPost] public ActionResult GetData(QueryFilters model) { return Json("Ho ho ho and a bottle of rum."); } 

Oh and note that actions should return ActionResults, not strings.

Also remove the following line from your global.asax:

 ValueProviderFactories.Factories.Add(new JsonValueProviderFactory()); 

ASP.NET MVC 3 already has this built-in module.

Or, if for some reason you need to have a filters action argument, you can also change the JSON request you send to this:

 data: JSON.stringify({ filters: { Filters: [ { "Field": 3, "Operator": 0, "Values": ["30.01.2012.", "30.01.2012."] }, { "Field": 2, "Operator": 0, "Values": ["-1"] }, { "Field": 0, "Operator": 0, "Values": ["some-string"] } ] } }), 

Now there is no more ambiguity.