How to desrialize JSON and get out a value in C#

Question

// Get the JSON response.
                    string contentString = await response.Content.ReadAsStringAsync();

                    Console.WriteLine(contentString);
                    var rs = Newtonsoft.Json.Linq.JToken.Parse(contentString);
 Result rst = JsonConvert.DeserializeObject<Result>(contentString);

//Here i need to get the first value in the description as it appears to be a list

var firstValue= rst.description;

//And also a value from caption
var captionValue = rst.Caption


 public class Result
    {
        public Category[] categories { get; set; }
        public Description description { get; set; }
        public string requestId { get; set; }
        public  Caption caption { get; set;}
        public Metadata metadata { get; set; }
        public Color color { get; set; }

    }

    public class Description
    {
        public string[] tags { get; set; }
        public Caption[] captions { get; set; }
    }

    public class Caption
    {
        public string text { get; set; }
        public float confidence { get; set; }
    }

    public class Metadata
    {
        public int width { get; set; }
        public int height { get; set; }
        public string format { get; set; }
    }

    public class Color
    {
        public string dominantColorForeground { get; set; }
        public string dominantColorBackground { get; set; }
        public string[] dominantColors { get; set; }
        public string accentColor { get; set; }
        public bool isBWImg { get; set; }
    }

    public class Category
    {
        public string name { get; set; }
        public float score { get; set; }
    }
} 

JSON DATA:

{
   "categories": [
      {
         "name": "abstract_",
         "score": 0.00390625
      },
      {
         "name": "others_",
         "score": 0.0234375
      },
      {
         "name": "outdoor_",
         "score": 0.00390625
      }
   ],
   "description": {
      "tags": [
         "road",
         "building",
         "outdoor",
         "street",
         "night",
         "black",
         "city",
         "white",
         "light",
         "sitting",
         "riding",
         "man",
         "side",
         "empty",
         "rain",
         "corner",
         "traffic",
         "lit",
         "hydrant",
         "stop",
         "board",
         "parked",
         "bus",
         "tall"
      ],
      "captions": [
         {
            "text": "a close up of an empty city street at night",
            "confidence": 0.7965622853462756
         }
      ]
   },
   "requestId": "dddf1ac9-7e66-4c47-bdef-222f3fe5aa23",
   "metadata": {
      "width": 3733,
      "height": 1986,
      "format": "Jpeg"
   },
   "color": {
      "dominantColorForeground": "Black",
      "dominantColorBackground": "Black",
      "dominantColors": [
         "Black",
         "Grey"
      ],
      "accentColor": "666666",
      "isBWImg": true
   }
}

I understand What I wanted is simple but looks a bit more complex for me. I have use the

Result //rst = JsonConvert.DeserializeObject<Result>(contentString);

to connect and get the response and I have passed in the contentString which is the JSON data. I just want to get out my desired value. Using description as an example will be more helpful. Thanks

There's pre-existing NuGet package that interfaces with Congnitive Services: [Microsoft.ProjectOxford.Vision](https://www.nuget.org/packages/Microsoft.ProjectOxford.Vision/), perhaps there's no point in reinventing the wheel? — orhtej2, Jul 16 '18 at 07:53
Possible duplicate of [How to get some values from a JSON string in C#?](https://stackoverflow.com/questions/17617594/how-to-get-some-values-from-a-json-string-in-c) — BugFinder, Jul 16 '18 at 08:33

score 2 · Accepted Answer · answered Jul 16 '18 at 08:06

Complementing Andrew's answer, you can use the following class structure:

    public class Result
    {
        public Category[] categories { get; set; }
        public Description description { get; set; }
        public string requestId { get; set; }
        public Metadata metadata { get; set; }
        public Color color { get; set; }
    }

    public class Description
    {
        public string[] tags { get; set; }
        public Caption[] captions { get; set; }
    }

    public class Caption
    {
        public string text { get; set; }
        public float confidence { get; set; }
    }

    public class Metadata
    {
        public int width { get; set; }
        public int height { get; set; }
        public string format { get; set; }
    }

    public class Color
    {
        public string dominantColorForeground { get; set; }
        public string dominantColorBackground { get; set; }
        public string[] dominantColors { get; set; }
        public string accentColor { get; set; }
        public bool isBWImg { get; set; }
    }

    public class Category
    {
        public string name { get; set; }
        public float score { get; set; }
    }

And then use Newsontsoft's Result result = JsonConvert.DeserializeObject<Result>(json); to deserialize your Json.

Newtonsoft download: https://www.nuget.org/packages/Newtonsoft.Json/

Hello, i created the class but how do i access each values in the variable as its turns out to be an array. e.g i need get the first value in description and the text in caption Result rsult = JsonConvert.DeserializeObject(contentString); var value1= rsult.description; — Oluwatosin Samuel Babalola, Jul 16 '18 at 14:09
Nice! If you only need one specific value from the Json, you can also take a look in `SelectToken` ([link](https://www.newtonsoft.com/json/help/html/SelectToken.htm)), as pointed out by Mahesh. — Nathalia Soragge, Jul 16 '18 at 18:04

score 1 · Answer 2 · answered Jul 16 '18 at 07:59

The best option here would be to create a model that will represent the response and then deserialize the response into an instance of the model using JsonConvert.DeserializeObject of Newtonsoft Json.Net. It will be much more OOP-like approach, easier to maintain and extend.

See an example here.

score 0 · Answer 3 · answered Jul 16 '18 at 08:03

0

https://www.newtonsoft.com/json/help/html/SelectToken.htm

Check the JToken class in details. Everything you can extract either using whole class like structure using deserialization or extract any specific value directly

answered Jul 16 '18 at 08:03

Mahesh Malpani

1,782
16
27

score 0 · Answer 4 · answered Jul 16 '18 at 15:56

To get the caption under description, first generate a class with the JSON response. You can use the link to do that [json2c#][1]

//Using the result class

// Get the JSON response.
  string contentString = await response.Content.ReadAsStringAsync();
  Result rsult = JsonConvert.DeserializeObject<Result>(contentString);
  var dsc = rsult.description;
  string cap = dsc.captions[0].text.ToString();

public class Result
    {
        public Category[] categories { get; set; }
        public Description description { get; set; }
        public string requestId { get; set; }
        public Metadata metadata { get; set; }
        public Color color { get; set; }
    }

    public class Description
    {
        public string[] tags { get; set; }
        public Caption[] captions { get; set; }
    }

    public class Caption
    {
        public string text { get; set; }
        public float confidence { get; set; }
    }

    public class Metadata
    {
        public int width { get; set; }
        public int height { get; set; }
        public string format { get; set; }
    }

    public class Color
    {
        public string dominantColorForeground { get; set; }
        public string dominantColorBackground { get; set; }
        public string[] dominantColors { get; set; }
        public string accentColor { get; set; }
        public bool isBWImg { get; set; }
    }

    public class Category
    {
        public string name { get; set; }
        public float score { get; set; }

  [1]: http://json2csharp.com/

How to desrialize JSON and get out a value in C#

4 Answers4