Using System.Web.Script.Serialization.JavascriptSerializer to deserialize JSON - how to?

Maxim Zaslavsky picture Maxim Zaslavsky · Sep 20, 2009 · Viewed 23.9k times · Source

Note: I posted a similar question, which was the ancestor of this question, as I was originally thinking of using JSON.NET to parse the JSON, but I'm using the built-in deserializer, so it's a different question.

This is what I'm trying to do: I have a class called Item, for example. The json has many "elements" (if that's what they are called - they mimic the Item class), and each contains 3 fields: an integer named id, a string named name, and a datetime named creationTime. I would like to parse all of these Item "elements" from the json into a list of Item objects. I have created 3 fields in the Item class to match the JSON.

This is what I'm currently doing:

JavaScriptSerializer ser = new JavaScriptSerializer();          
List<Item> items = ser.Deserialize<Item>(new StreamReader(response.GetResponseStream()).ReadToEnd());

However, this isn't working, because I "cannot implicitly convert type 'superapi.Item' to 'System.Collections.Generic.List<superapi.Item>'". Thus, I do not know how to approach this problem, as there are many elements of the Item architecture in the JSON. Is it somehow possible to do this in a foreach loop, to find each deserialized Item in the JSON, add that to the list, and continue the loop? I'm going to attempt to do just that with some similar code, and I will post my results.

Thanks!

UPDATE: This is what some of the JSON looks like:

[{
    "Id": 1,
    "Name": "First item name",
    "creationTime": "\/Date(1247258293690)\/"
},
{
    "Id": 2,
    "Name": "Second item name",
    "creationTime": "\/Date(1247088323430)\/"
}]

This is what my Item class looks like:

public class Item
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public DateTime creationTime { get; set; }
    }

Answer

Marc Gravell picture Marc Gravell · Sep 20, 2009

I tried with your example json / class, and the following works fine:

List<Item> items = ser.Deserialize<List<Item>>(json);

Is the actual code any different?

(where json is the string - feel free to replace by ReadToEnd etc; or use WebClient.DownloadString, which is simpler)