JSON Deserialize is not working with List object

Question

I have a JSON file such as:

{
   "samples":[
      {
         "date":"2014-08-10T09:00:00Z",
         "temperature":10,
         "pH":4,
         "phosphate":4,
         "chloride":4,
         "nitrate":10
      },
      {
         "date":"2014-08-12T09:05:00Z",
         "temperature":10.5,
         "pH":5,
         "chloride":4,
         "phosphate":4
      },
      {
         "date":"2014-08-14T09:02:00Z",
         "temperature":10.8,
         "pH":3,
         "phosphate":4
      },
      {
         "date":"2014-08-16T09:02:00Z",
         "temperature":11.2,
         "pH":6,
         "chloride":4
      },
      {
         "date":"2014-08-18T08:58:00Z",
         "temperature":10.9,
         "pH":10,
         "chloride":4,
         "phosphate":4,
         "nitrate":10
      },
      {
         "date":"2014-08-20T09:10:00Z",
         "temperature":9.3,
         "pH":6,
         "phosphate":4
      },
      {
         "date":"2014-08-22T09:01:00Z",
         "temperature":9.5,
         "pH":10,
         "chloride":4,
         "phosphate":4,
         "nitrate":10
      }
   ]
}

I need to access each sub-element like "temperature", "pH" and so on to calculate their avarage. To do this, I wanted to use deserializer. First of all, I created a custom class to hold json's parameters,

public class SampleClass
{
    public float temperature { get; set; } = 0;
    public int pH { get; set; } = 0;
    public int phosphate { get; set; } = 0;
    public int chloride { get; set; } = 0;
    public int nitrate { get; set; } = 0;

}

Right after, I applied the deserializer with using this custom class;

List<SampleClass> json = JsonConvert.DeserializeObject<List<SampleClass>>(jsonStr);

With the above line of code, I am taking an error;

Newtonsoft.Json.JsonSerializationException: Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List`1[GeneralKnowledge.Test.App.Tests.SampleClass]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.
To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.
Path 'samples', line 2, position 14.

What would you suggest me to solve it? Thanks in advance.

This is the whole json file. I shared all of it.

Ozan Yurtsever
– Ozan Yurtsever

2019-05-11 19:56:22 +00:00
Commented May 11, 2019 at 19:56 — Ozan Yurtsever
– Ozan Yurtsever, Commented May 11, 2019 at 19:56

dbc · Accepted Answer · 2019-05-11 20:02:07Z

3

Assuming that your JSON looks like:

{
   "samples":[ ... ]
}

You have an outer container object that encapsulates your array of samples. You need to deserialize to a data model that reflects this structure. One easy way to do it is to use an anonymous object, along with JsonConvert.DeserializeAnonymousType():

var result = JsonConvert.DeserializeAnonymousType(jsonStr, new { samples = default(List<SampleClass>) })
    .samples;

This approach avoids loading the JSON into an intermediate dynamic or JToken representation.

Sample fiddle here.

answered May 11, 2019 at 20:02

dbc

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Comments

Berianidze Luka · Accepted Answer · 2019-05-11 19:53:37Z

1

Try this:

dynamic json = Newtonsoft.Json.JsonConvert.DeserializeObject(json_string);
List<SampleClass> result = JsonConvert.DeserializeObject<List<SampleClass>>(json.samples.ToString());

but if it doesn't,use this

 List<SampleClass> result = new List<SampleClass>();
 foreach (var item in json.samples)
 {               
  result.Add(Newtonsoft.Json.JsonConvert.DeserializeObject<SampleClass>(item.ToString()));
 }

answered May 11, 2019 at 19:53

Berianidze Luka

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