Generate a list of custom objects from Json object using LINQ

Question

Currently I am facing an issue to create a LINQ statement which will generate the list of objects that I want. The following section is an example of the LINQ object that i want to process.

{
  "successful": "true",
  "result": [
    [
      {
        "Param1": "A1",
        "Param2": "A2",
        "Param3": "A3",
        "Param4": "A4",
        "Param5": "1",
        "Param6": "A5",
      },
      {
        "Param1": "B1",
        "Param2": "B2",
        "Param3": "B3",
        "Param4": "B4",
        "Param5": "2",
        "Param6": "B5",
      },
      {
        "Param1": "C1",
        "Param2": "C2",
        "Param3": "C3",
        "Param4": "C4",
        "Param5": "2",
        "Param6": "C5",
      }
    ]
  ]
}

I have a custom object class as follow,

public class CContainer
{
    public string param1{ get; set; }

    public string param2{ get; set; }

    public string param3{ get; set; }
}

My end goal is to create a list of CContainer objects, that contain only the first 3 parameters (Param1, Param2, and Param3) for each item under the 'result' category. Also, I would like to select only item which its Param5 == "2". I am currently unable to do that using LINQ, please advice.

The following snippet don't work (even if I remove the 'Where' clause).

    List<CContainer> testList = new List<CContainer>();
    string responseRet = await response.Content.ReadAsStringAsync();
    JObject o = JObject.Parse(responseRet);

    testList =
     (from item in o["result"]
      where item["Param5"].Value<string>() == "2"
      select new CCOntainer
      {
          param1 = item["Param1"].Value<string>(),
          param2 = item["Param2"].Value<string>(),
          param3 = item["Param3"].Value<string>(),
      }).ToList();

Why are you not using the property attributes and JsonConvert.Deserialize<T>() method? — toadflakz
– toadflakz, Commented Apr 13, 2017 at 13:56
I am not sure how to extract only Param1, Param2, Param3, under result with certain condition using Deserialize method. — YYTan
– YYTan, Commented Apr 13, 2017 at 14:00
Are you aware your results property is an array with a single element... and that single element is itself an array of your CContainer object? Is that a mistake or intentional? — Jamiec
– Jamiec, Commented Apr 13, 2017 at 14:16
I just realized that it is an array with a single element. I am not familiar with JSON, and I think this format is made intentionally, and I can't change it. Thanks for pointing it out. — YYTan
– YYTan, Commented Apr 13, 2017 at 14:57

ImDarrenG · Accepted Answer · 2017-04-13 14:07:38Z

1

"result" in your json sample is an array containing one array, which contains your objects.

So either change the json so that "result" is a 1D array, or, something along the lines of:

testList =
 (from item in o["result"].FirstOrDefault()
// etc.

answered Apr 13, 2017 at 14:07

ImDarrenG

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1 Comment

YYTan Over a year ago

Thanks, after extracting the first element, I can process it to the list I want, I guess its the design of the JSON object.

toadflakz · Accepted Answer · 2017-04-13 14:23:29Z

0

You are trying to do two different things at once.

You are trying to deserialize JSON into objects.
You are trying to filter the returned results.

I suggest you treat them as separate operations to simplify your code.

To deserialize all the objects using JsonConvert.DeserializeObject<T>() setup your classes as follows:

[JsonObject(MemberSerialization.OptIn)]
public class Result
{
    [JsonProperty("success")]
    public bool Success{ get; set; }

    [JsonProperty("result")]
    public List<List<JsonCContainer>> Items{ get; set; }

}

[JsonObject(MemberSerialization.OptIn)]
public class JsonCContainer
{
    [JsonProperty("Param1")]
    public string param1{ get; set; }

    [JsonProperty("Param2")]
    public string param2{ get; set; }

    [JsonProperty("Param3")]
    public string param3{ get; set; }

    [JsonProperty("Param5")]
    public string param5{ get; set; }

}

public class CContainer
{
    public string param1{ get; set; }
    public string param2{ get; set; }
    public string param3{ get; set; }
}

You would get your Result object with the following code:

string responseRet = await response.Content.ReadAsStringAsync();
Result resultObj = JsonConvert.DeserializeObject<Result>(responseRet);

Once you've got your Result class object, then do the filtering:

return resultObj.Items.SelectMany(x => x)
                .Where(x => x.param5 == "2")
                .Select(y => new CContainer()
                                 {
                                   param1 = y.param1, 
                                   param2 = y.param2, 
                                   param3 = y.param3
                                 }).ToList();

edited Apr 13, 2017 at 14:23

answered Apr 13, 2017 at 14:15

toadflakz

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2 Comments

ImDarrenG Over a year ago

Some really nice code, but the json structure is the issue.

toadflakz Over a year ago

Updated to handle the multidimensional array.

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