ASP.NET MVC: Json(IDictionary<string, string>) converts to array of key-value pairs

Question

If I have an IDictionary<string, string> MyDictionary that resembles this:

{
    {"foo", "bar"},
    {"abc", "xyz"}
}

and in my MVC controller I have a method like so:

[HttpPost]
public JsonResult DoStuff()
{
    return Json(MyDictionary);
}

...it sends back something like:

[
 {"Key":"foo", "Value":"bar"},
 {"Key":"abc", "Value":"xyz"}
]

I was expecting (and wanting) something like:

{
 "foo":"bar",
 "abc":"xyz"
}

How can I accomplish this?

UPDATE

So this is directly related to the fact that this project was upgraded from an ASP.NET 2.0 application that used a custom JSON serializer; apparently, for backwards compatibility, they made that the default JSON serializer in the MVC application. Ultimately I overrode that behavior in my controller with the Json.NET result, and my problem was solved.

You can take a look at this post: stackoverflow.com/questions/32253259/… — Adrian Stanescu
– Adrian Stanescu, Commented Dec 15, 2015 at 21:37
That is the dictionary format used by DataContractJsonSerializer. Are you using this serializer? See Json serializers in ASP.NET and other for a list of serializers used in various asp.net platforms. Which exact asp.net technology are you using? — dbc
– dbc, Commented Dec 15, 2015 at 21:45
As best I can tell asp.net-mvc doesn't use DataContractJsonSerializer by default in any version. Could you have overridden the default behavior? See ASP.NET MVC: Controlling serialization of property names with JsonResult for an example of this. To use Json.NET instead see Using JSON.NET as the default JSON serializer in ASP.NET MVC 3 - is it possible?. — dbc
– dbc, Commented Dec 15, 2015 at 21:55
It's entirely possible... there's a lot of weird settings in this project. :) — user610217
– user610217, Commented Dec 16, 2015 at 14:33

Nkosi · Accepted Answer · 2015-12-22 04:20:38Z

4

With the default Json serializer(Json.Net), It should return you the below JSON structure from a Dictionary<string, string>

{"Foo": "TTTDic", "Bar": "Scoo"}

With your action method:

[HttpPost]
public JsonResult DoStuff()
{
    var MyDictionary = new Dictionary<string, string>();
    MyDictionary.Add("Foo", "TTTDic");
    MyDictionary.Add("Bar", "Scoo");
    return Json(MyDictionary);
}

Verified this in MVC5 and MVC6.

If you are still having problems, why not create a simple POCO with the properties you want?

public class KeyValueItem
{
    public string Foo { set; get; }
    public string Abc { set; get; }
}

And create an object of that, set the property values and send that as JSON.

[HttpPost]
public JsonResult DoStuff()
{
  var item = new KeyValueItem
  {
      Foo="Bee",
      Abc="Scoo"
  };
  return Json(item );
}

edited Dec 22, 2015 at 4:20

Nkosi

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answered Dec 15, 2015 at 21:43

Shyju

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4 Comments

jpgrassi Over a year ago

Only a note: The POCO would only work if the dictionary is made of a concrete object. Usually people use Dictionaries like that for dynamic values.

user610217 Over a year ago

Exactly my situation; I cannot use a POCO in this case as the "properties" are dynamic.

Shyju Over a year ago

What version is yours ? I verified it in MVC5 and 6 It converts the dictionary to the JSON format you want.

user610217 Over a year ago

Looks like when this application was upgraded to MVC5 from the legacy ASP.NET, they purposely specified a custom json serializer for backwards compatibility (they were using it before the upgrade). I'll mark this as the answer, since it got me on the right track on what to look for. Thanks!

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