How can I deserialize JSON to a simple Dictionary<string,string> in ASP.NET?

Question

I have a simple key/value list in JSON being sent back to ASP.NET via POST. Example:

{ "key1": "value1", "key2": "value2"}

I AM NOT TRYING TO DESERIALIZE INTO STRONGLY-TYPED .NET OBJECTS

I simply need a plain old Dictionary(Of String, String), or some equivalent (hash table, Dictionary(Of String, Object), old-school StringDictionary--hell, a 2-D array of strings would work for me.

I can use anything available in ASP.NET 3.5, as well as the popular Json.NET (which I'm already using for serialization to the client).

Apparently neither of these JSON libraries have this forehead-slapping obvious capability out of the box--they are totally focused on reflection-based deserialization via strong contracts.

Any ideas?

Limitations:

1. I don't want to implement my own JSON parser
2. Can't use ASP.NET 4.0 yet
3. Would prefer to stay away from the older, deprecated ASP.NET class for JSON

Answer 1

Take a look at the System.Runtime.Serialization.Json namespace. It has the DataContractJsonSerializer class that can be of help in your case.

Also, take a look at http://www.codeplex.com/Json

Answer 2

Edit: This works, but the accepted answer using Json.NET is much more straightforward. Leaving this one in case someone needs BCL-only code.

It's not supported by the .NET framework out of the box. A glaring oversight--not everyone needs to deserialize into objects with named properties. So I ended up rolling my own:

<Serializable()> Public Class StringStringDictionary
    Implements ISerializable
    Public dict As System.Collections.Generic.Dictionary(Of String, String)
    Public Sub New()
        dict = New System.Collections.Generic.Dictionary(Of String, String)
    End Sub
    Protected Sub New(info As SerializationInfo, _
          context As StreamingContext)
        dict = New System.Collections.Generic.Dictionary(Of String, String)
        For Each entry As SerializationEntry In info
            dict.Add(entry.Name, DirectCast(entry.Value, String))
        Next
    End Sub
    Public Sub GetObjectData(info As SerializationInfo, context As StreamingContext) Implements ISerializable.GetObjectData
        For Each key As String in dict.Keys
            info.AddValue(key, dict.Item(key))
        Next
    End Sub
End Class

Called with:

string MyJsonString = "{ \"key1\": \"value1\", \"key2\": \"value2\"}";
System.Runtime.Serialization.Json.DataContractJsonSerializer dcjs = new
  System.Runtime.Serialization.Json.DataContractJsonSerializer(
    typeof(StringStringDictionary));
System.IO.MemoryStream ms = new
  System.IO.MemoryStream(Encoding.UTF8.GetBytes(MyJsonString));
StringStringDictionary myfields = (StringStringDictionary)dcjs.ReadObject(ms);
Response.Write("Value of key2: " + myfields.dict["key2"]);

Sorry for the mix of C# and VB.NET...

Answer 3

Json.NET does this...

string json = @"{""key1"":""value1"",""key2"":""value2""}";

Dictionary<string, string> values = JsonConvert.DeserializeObject<Dictionary<string, string>>(json);

Answer 4

I did discover .NET has a built in way to cast the JSON string into a Dictionary<String, Object> via the System.Web.Script.Serialization.JavaScriptSerialize type in the 3.5 System.Web.Extensions assembly. Use the method DeserializeObject(String).

I stumbled upon this when doing an ajax post (via jquery) of content type 'application/json' to a static .net Page Method and saw that the method (which had a single parameter of type Object) magically received this Dictionary.