Json.Net Select Object based on a value

Question

I have a Json object that looks like this:

{
     wvw_matches: [
          {
               wvw_match_id: "1-4",
               red_world_id: 1011,
               blue_world_id: 1003,
               green_world_id: 1002,
               start_time: "2013-09-14T01:00:00Z",
               end_time: "2013-09-21T01:00:00Z"
          },
          {
               wvw_match_id: "1-2",
               red_world_id: 1017,
               blue_world_id: 1021,
               green_world_id: 1009,
               start_time: "2013-09-14T01:00:00Z",
               end_time: "2013-09-21T01:00:00Z"
          }
     ]
}

It contains a lot more objects in the array than the example above shows. Anyway, I need to select the Json object based on the wvw_match_id.

How would I achieve this? :)

Brian Rogers · Accepted Answer · 2013-09-21 00:01:07Z

10

Since it seems from the comments that you're already semi-comfortable with the idea of using JObject and Linq, here is an example program demonstrating how to get a specific match from your JSON by ID using that approach:

class Program
{
    static void Main(string[] args)
    {
        string json = @"
        {
            wvw_matches: [
                {
                    wvw_match_id: ""1-4"",
                    red_world_id: 1011,
                    blue_world_id: 1003,
                    green_world_id: 1002,
                    start_time: ""2013-09-14T01:00:00Z"",
                    end_time: ""2013-09-21T01:00:00Z""
                },
                {
                    wvw_match_id: ""1-2"",
                    red_world_id: 1017,
                    blue_world_id: 1021,
                    green_world_id: 1009,
                    start_time: ""2013-09-14T01:00:00Z"",
                    end_time: ""2013-09-21T01:00:00Z""
                }
            ]
        }";

        string matchIdToFind = "1-2";
        JObject jo = JObject.Parse(json);

        JObject match = jo["wvw_matches"].Values<JObject>()
            .Where(m => m["wvw_match_id"].Value<string>() == matchIdToFind)
            .FirstOrDefault();

        if (match != null)
        {
            foreach (JProperty prop in match.Properties())
            {
                Console.WriteLine(prop.Name + ": " + prop.Value);
            }
        }
        else
        {
            Console.WriteLine("match not found");
        }

    }
}

Output:

wvw_match_id: 1-2
red_world_id: 1017
blue_world_id: 1021
green_world_id: 1009
start_time: 9/14/2013 1:00:00 AM
end_time: 9/21/2013 1:00:00 AM

edited Sep 21, 2013 at 0:01

answered Sep 20, 2013 at 23:47

Brian Rogers

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2 Comments

German Over a year ago

Just in case not every array item is guaranteed to have a wvw_match_id, I'd slightly modify the where condition to .Where(m => m["wvw_match_id"]?.Value<string>() == matchIdToFind) to avoid a runtime exception.

Marcelo Scofano Diniz Over a year ago

This example should be at www.newtonsoft.com/json/help/html/QueryJsonSelectTokenBasedOnValue.htm

Ry- · Accepted Answer · 2018-09-05 16:45:24Z

0

You should just serialize it as you normally would then filter the array with LINQ. So I'm just going to assume you've defined a class for the objects in this array, call it MyObj

MyObj[] myObjects = serializer.Deserialize<MyObj[]>(jsonAsAString);
var filteredObjs = myObjects.Where(x => x.wvw_match_id == "the id i'm filtering on");

Keep in mind it's much easier to work with native C# objects than JSON. JSON.NET is for doing the serialization/deserialization. Filtering your collection is something you want to do with iteration or LINQ.

edited Sep 5, 2018 at 16:45

Ry-♦

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answered Sep 20, 2013 at 22:28

evanmcdonnal

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7 Comments

Jazerix Over a year ago

isn't it possible without serializing it?

evanmcdonnal Over a year ago

@Jazerix I was just writing an edit about that. Not that I know of, and even if it were I think it's a worse approach.

Jazerix Over a year ago

Well, I would be ever so happy if I could avoid serializing it :3 but if there are no way around it, I guess I'm gonna have to do it :(

evanmcdonnal Over a year ago

@Jazerix I would be shocked if json.NET offered you anyway to do it without serialzing the data. That's not what the library is made for and it would contradict the separation of concerns design principal.

Jazerix Over a year ago

I've been having no problem doing it without so far. Json.net offers its own Linq library. I'm no expert on this area, and I don't mean to offend you in any way, however it makes no sense to me, you can do a JObject.Select, JObject.Where ect... with it, if you have to serialize it first :)

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