Close this search box. and Deserializing Anonymous Types

I had a situation where I had to deserialize a small chunk of JSON-formatted data and I didn’t want to create a class for it since it was a very specific use and I was confident there wasn’t a need to reuse it elsewhere in the application.

If I did have a class defined for the JSON data, I could easily use JSON.NET’s JsonConvert.DeserializeObject method:

1 : string myJson = "[{id: 10, typeID: 4},{id: 100, typeID: 3}]";
2 : MyObject obj = JsonConvert.DeserializeObject<MyObject>(myJson);
3 : Console.WriteLine(obj[0].id);

So this is easy to do, but I really didn’t want to define a MyObject class for a one-time use.  So I thought I’d go the route of an anonymous type and use JSON.NET’s JsonConvert.DeserializeAnonymousType method.  I thought it was a bit vague how to use this since it asks for a type parameter – but since my output will be an anonymous type, what would my type parameter be?

Well, the best way that I came up with in a short period of time was to define a dummy anonymous type and pass it to the JsonConvert method.  It’s a little bit of overhead and an extra line of code, but it does work.

1 : string myJson = "[{id: 10, typeID: 4},{id: 100, typeID: 3}]";
2 : var dummyObject = new[]{new {id = 0, typeID = 0}};
3 : var myObjects = JsonConvert.DeserializeAnonymousType(myJson, dummyObject);
4 : Console.WriteLine(myObjects[0].id);

The slightly confusing part was the Intellisense provided by

Seeing the ‘T’ type parameter makes you think you need a call to typeof() or something similar.  But in the case of deserializing to an anonymous type, you just need an instance of the anonymous type.

I thought I may have been missing something, but a little Bing research showed that there were similar approaches taken (see here and here).

Posted on Friday, January 6, 2012 1:08 PM C# , JSON.NET | Back to top

This article is part of the GWB Archives. Original Author: DAVID HOERSTER

Related Posts