using System;

using System.Text.Json;

using System.Text.Json.Serialization;

public class Program

{

    public static void Main()

    {

        string json = "{\"d\":{\"__metadata\":{\"id\":\"http://my.dev.int:8000/sap/opu/odata/sap/ZFIORI_SERIAL_NUMBERS_SRV/MATERIALSet('250')\",\"uri\":\"http://my.dev.int:8000/sap/opu/odata/sap/ZFIORI_SERIAL_NUMBERS_SRV/MATERIALSet('250')\",\"type\":\"ZFIORI_SERIAL_NUMBERS_SRV.MATERIAL\"},\"MATNR\":\"250\",\"MAKTX\":\"X:K10/MF250\"}}";

        var myjson = System.Text.Json.JsonSerializer.Deserialize<MyJson>(json);

        Console.WriteLine(myjson.D.MATNR);

        Console.WriteLine(myjson.D.MetaB.ID);

    }

}

​

public class MyJson

{

    [JsonPropertyName("d")]

    public MetaData D {get; set;}

}

​

public class MetaData

{

   [JsonPropertyName("__metadata")]

   public MetaBase MetaB {get; set;}

   public string MATNR { get; set; }

   public string MAKTX { get; set; }    

}

​

public class MetaBase

{

   [JsonPropertyName("id")]

   public string ID {get; set;}

   [JsonPropertyName("uri")]

   public string Uri {get; set;}

   [JsonPropertyName("type")]

   public string Type {get; set;}

}