Trouble deserializing rather simple JSON data using JSON.NET

Question

I have problem with deserializing some JSON data which looks like this:

{
    "Var1": 0,
    "Var2": 2,
    "Var3": -1,
    "Var4": 5,
    "Var5": 1,
    "Var6": 3
}

This is located on a remote server and I fetch it then deserialize using this method in a separate class:

public static T _download_serialized_json_data<T>() where T : new()
{
    using (var w = new WebClient())
    {
        var json_data = string.Empty;
        try
        {
            json_data = w.DownloadString("http://url_to_json_data.json");
        }
        catch (Exception) { }
        return !string.IsNullOrEmpty(json_data) ? JsonConvert.DeserializeObject<T>(json_data) : new T();
    }
}

My JSON class:

public class Variables
{
    public int Var1 { get; set; }
    public int Var2 { get; set; }
    public int Var3 { get; set; }
    public int Var4 { get; set; }
    public int Var5 { get; set; }
    public int Var6 { get; set; }
}

Then in a different class when I need to access the data, I do this:

List<JsonClass.Variables> VARS = JsonClass._download_serialized_json_data<List<JsonClass.Variables>>();

System.Console.WriteLine("Variable 1: " + VARS[0].Var1);

And in the last part I get a massive exception thrown in my face saying this:

Newtonsoft.Json.JsonSerializationException: Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List`1[Solution1.JsonClass+Variables]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.

How would I properly access those simple integers without overdoing the thing? I tried dictionaries but that didn't work out too well. Thank you for your time.

The sample data you have given is not an array, just one instance of the class. Are you sure it is an array (List)? — Mark PM
– Mark PM, Commented Jan 27, 2014 at 22:44
Looking at your examples the JSON only contains one object, not an array of objects so the generic argument for your download-method should be JsonClass.Variables, not List<JsonClass.Variables>. — Mark
– Mark, Commented Jan 27, 2014 at 22:44
The whole file is exactly what I have posted there. It doesnt contain the [ ] array brackets. Only { and }. — user3242355
– user3242355, Commented Jan 27, 2014 at 22:45

Ben Allred · Accepted Answer · 2014-01-27 22:46:46Z

4

Try this instead

JsonClass.Variables VARS = JsonClass._download_serialized_json_data<JsonClass.Variables>();

System.Console.WriteLine("Variable 1: " + VARS.Var1);

You're original code was expecting to deserialize a list of JsonClass.Variables, but your example JSON only has a single object.

answered Jan 27, 2014 at 22:46

Ben Allred

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