ASP.NET WebAPI JSON Binding Case-Sensitivity

Question

Upgrading from ASP.NET WebAPI Beta to RC has provided some amount of excitement and a great deal of frustration. I have been able to work through the majority of the issues, but the one that is biting me right now is case-sensitivity of JSON request data.

The formatter used for JSON requests (which by default is a JSON.NET formatter) appears to be case sensitive while the formatter used for form-urlencoded data does not. Is there a way to configure the JSON requests to use a case-insensitive formatter?

Here is a simple example to illustrate the problem that I am having with JSON requests:

HTML / JavaScript

<button id="tester">Click here!</button> <script type="text/javascript"> $(function () { $("#tester").on("click", function() { $.ajax({ type: "POST", url: "/Api/Test/Index/" + 168, data: ko.toJSON({ key: 123, value: "test value" }), // THIS FAILS // Key: 123, Value: "test value" <- BUT THIS WORKS contentType: "application/json; charset=utf-8", statusCode: { 200: function () { $("body").append("<p>Success</p>"); }, 400: function () { $("body").append("<p>Failure</p>"); } } }).always(function () { $("body").append("<hr />"); }); }); }); </script>

C#

public class TestController : ApiController { public HttpResponseMessage Index(int? id, KeyValuePair<int, string> test) { if (id != 168 || test.Key != 123 || test.Value != "test value") return Request.CreateResponse(HttpStatusCode.BadRequest); return Request.CreateResponse(HttpStatusCode.OK); } }

I've provided a comment on the line where the JSON data is provided. I would rather not break convention with my JavaScript objects by proper casing property members and I certainly do not want to break convention by lower casing my C# properties. Any thoughts?

I'm a bit confused here. You send your data within a POST request - in other words, within a request body. But in the HTTP documentation it's said that header fields (and values) are considered case-insensitive, and there's nothing about the body... Why do you think "it's not the behaviour for form-urlencoded data", I wonder? — raina77ow
– raina77ow, Commented Jun 29, 2012 at 14:52
@raina77ow This isn't really a question about the HTTP specification but the behavior of JSON.NET formatter used by ASP.NET WebAPI RC. The FormUrl formatter appears to be case-insensitive while the JSON.NET formatter is case-sensitive. — Phil Klein
– Phil Klein, Commented Jun 29, 2012 at 15:33
I think case-sensitivity is correct. Why would you need case-insensitivity while C# and JavaScript are both case-sensitive? — Aliostad
– Aliostad, Commented Jun 29, 2012 at 15:56
I realize that they are both case sensitive, but the value provider or formatter used for parameter binding does not need to be case-sensitive as evidenced by the behavior of form-urlencoded data. I'll update the question to reflect this. Thanks. — Phil Klein
– Phil Klein, Commented Jun 29, 2012 at 16:08

Mike Wasson · Accepted Answer · 2012-06-29 17:48:36Z

25

The Json.NET formatter is case insensitive for deserialization (json -> CLR).

On serialization, you can get camel casing by using the CamelCasePropertyNamesContractResolver.

In your Global.asax:

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter; json.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();

answered Jun 29, 2012 at 17:48

Mike Wasson

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4 Comments

Phil Klein Over a year ago

I believed this to be the case, but I haven't been able to prove that behavior. Please see my related question: stackoverflow.com/questions/11266695/…

Mike Wasson Over a year ago

Hmm ... I just did some experimenting with JsonConvert. Deserializing KeyValuePair<T> is case-sensitive, like you say, but if I create a POCO, the behavior is definitely case insensitive. Seems to be related to KeyValuePair having getters but no setters, because I defined my own version of KeyValuePair with setters and that worked.

Phil Klein Over a year ago

Ah, you might be on to something ... I'll do some further experimenting and see if I can determine how it is deserializing with matching cased keys. Thanks!

Schiavini Over a year ago

Do you know whether the same is possible in XML? See stackoverflow.com/questions/16835100/…

Community · Accepted Answer · 2017-05-23 12:09:24Z

After digging into this issue in significant depth I came to realize that I was hitting a bug in the Json.NET KeyValuePair converter. James Newton-King was kind enough to answer my related question and provided a link to the fix:

Json.NET Case-insensitive Property Deserialization

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