Passing Dynamic JSON Object to Web API - Newtonsoft Example

Question

I need to pass a dynamic JSON object to my Web API controller so that I can process it depending on what type it is. I have tried using the JSON.NET example that can be seen here but when I use Fiddler, I can see that the passed in JObect is always null.

This is an exert from the example pasted into Fiddler:

POST http://localhost:9185/api/Auto/PostSavePage/  HTTP/1.1
User-Agent: Fiddler
Content-type: application/json
Host: localhost
Content-Length: 88

{AlbumName: "Dirty Deeds",Songs:[ { SongName: "Problem Child"},{ SongName:  
"Squealer"}]}

Ans here is my very simple Web API controller method:

 [HttpPost]
 public JObject PostSavePage(JObject jObject)
 {        
     dynamic testObject = jObject;         
     // other stuff here
 }

I am new to this and I have a couple of questions around this area:

Am I doing something wrong in this particular example?

Arguably, more importantly, is there a better way to pass in a dynamic JSON object (from an JavaScript AJAX post)?

You should stringify your JavaScript object before posting it to the server. The data shown (currently) in your question does not represent valid JSON. — Perception, Dec 28 '12 at 15:29
I was not able to repro your issue in a newly created MVC4 Web.API project. I send a request with fiddler with the exact same values and the `jObject` parameter is properly filled with data. Maybe something is wrong with your routing, do you have any custom routes? — nemesv, Dec 28 '12 at 17:36
Thanks nemesv. I also tried a new project and you're right, the jObject is fine. I do have custom routes so will have a look there. — davy, Jan 01 '13 at 22:49

Mark Jones · Answer 1 · 2012-12-28T17:42:59.127

16

As per Perception's comment your JSON doesn't look valid. Run it through JSONLint and you get:

Parse error on line 1:
{    AlbumName: "Dirty De
-----^
Expecting 'STRING', '}'

Change it to have " around the field names:

{
    "AlbumName": "Dirty Deeds",
    "Songs": [
        {
            "SongName": "Problem Child"
        },
        {
            "SongName": "Squealer"
        }
    ]
}

Also have you tried swapping out your JObject for either a JToken or a Dynamic object (e.g. here)?

[HttpPost]
 public JObject PostSavePage(JToken testObject)
 {                
     // other stuff here
 }

OR

 [HttpPost]
 public JObject PostSavePage(dynamic testObject)
 {                
     // other stuff here
 }

edited Dec 28 '12 at 17:42

answered Dec 28 '12 at 17:37

Mark Jones

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Thanks, none of these suggestions is working for me. See nemesv's comment above. I think it must be something to do with my custom routes. – davy Dec 31 '12 at 12:25
@davy sorry to hear that. If you are able to see that testObject is null then your routes should be OK... can you get a breakpoint inside PostDavePage? I will try take another stab at answering if you have your route config to share. – Mark Jones Jan 02 '13 at 11:06
Thanks a lot. Something strange is going. I'm in th eprocess of copying files into my basic working solution. Hopefully then, it will work or I'll be able to pinpoint the problem. I think the project may be corrupted in some way as I'm getting some other weird errors that I wont go into yet as I don't get them in the new app. I will update when I find anything. Thanks again. – davy Jan 02 '13 at 12:36

score 4 · Accepted Answer · answered Jan 02 '13 at 16:18

Thanks to everyone who helped here. Unfortunately, I never got to the bottom of what was wrong.

I ported the project over piece by piece to a new project and it works fine.

For info, I have a RouteConfig class, which is quite simple at the moment:

public class RouteConfig
{       
    private static string ControllerAction = "ApiControllerAction";

    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapHttpRoute(
            name: ControllerAction,
            routeTemplate: "api/{controller}/{action}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    }
}

My call into the API now uses JSON.Stringify:

$.ajax("http://localhost:54997/api/values/PostSavePage/", {
    data:  JSON.stringify(jObject),                               
    contentType: 'application/json',
    type: 'POST'
});

The original API action works.

Note, that I'm only playing with this at the moment so the code is not the best but I thought it may be useful in basic form in case someone else has a similar issue.

are you sure of your controller in the first app ? http://localhost:9185/api/Auto/PostSavePage/ it must be AutoController — riadh gomri, Dec 06 '13 at 16:57

Passing Dynamic JSON Object to Web API - Newtonsoft Example

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