Converting C++ Class to JSON

How do I turn a C# object into a JSON string in .NET?

Please Note

Microsoft recommends that you DO NOT USE JavaScriptSerializer

See the header of the documentation page:

For .NET Framework 4.7.2 and later versions, use the APIs in the System.Text.Json namespace for serialization and deserialization. For earlier versions of .NET Framework, use Newtonsoft.Json.

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Original answer:

You could use the JavaScriptSerializer class (add reference to System.Web.Extensions):

using System.Web.Script.Serialization;

var json = new JavaScriptSerializer().Serialize(obj);

A full example:

using System;
using System.Web.Script.Serialization;

public class MyDate
{
    public int year;
    public int month;
    public int day;
}

public class Lad
{
    public string firstName;
    public string lastName;
    public MyDate dateOfBirth;
}

class Program
{
    static void Main()
    {
        var obj = new Lad
        {
            firstName = "Markoff",
            lastName = "Chaney",
            dateOfBirth = new MyDate
            {
                year = 1901,
                month = 4,
                day = 30
            }
        };
        var json = new JavaScriptSerializer().Serialize(obj);
        Console.WriteLine(json);
    }
}

Converting C++ class to JSON

JSON Spirit would allow you to do it like so:

Object addr_obj;

addr_obj.push_back( Pair( "house_number", 42 ) );
addr_obj.push_back( Pair( "road",         "East Street" ) );
addr_obj.push_back( Pair( "town",         "Newtown" ) );

ofstream os( "address.txt" );
os.write( addr_obj, os, pretty_print );
os.close();

Output:

{
    "house_number" : 42,
    "road" : "East Street",
    "town" : "Newtown"
}

The json_map_demo.cpp would be a nice place to start, I suppose.

Converting C# Objects to Json format

You didn't write which version of asp .net core you use.

In version 2.0 Json Newtonsoft library is used to handle json serialization/deserialization.

Product product = new Product();
product.Name = "Apple";
product.Expiry = new DateTime(2008, 12, 28);
product.Sizes = new string[] { "Small" };

string json = JsonConvert.SerializeObject(product);
// {
//   "Name": "Apple",
//   "Expiry": "2008-12-28T00:00:00",
//   "Sizes": [
//     "Small"
//   ]
// }

In version 3.0 has been introduced new default library for handling json operations System.Text.Json, but you can change configuration to still use Newtonsoft. Example usage of the System.Text.Json.

string jsonString;
jsonString = JsonSerializer.Serialize(weatherForecast);
// {
//  "Date": "2019-08-01T00:00:00-07:00",
//  "TemperatureCelsius": 25,
//  "Summary": "Hot",
//  "DatesAvailable": ["2019-08-01T00:00:00-07:00",
//  "2019-08-02T00:00:00-07:00"],
//  "TemperatureRanges": {
//      "Cold": {
//          "High": 20,
//          "Low": -10
//      },
//      "Hot": {
//          "High": 60,
//          "Low": 20
//      }
//  },
//  "SummaryWords": ["Cool",
//  "Windy",
//  "Humid"]
// }

Convert C# Object to Json Object

To create correct JSON first you need to prepare appropriate model. It can be something like that:

[DataContract]
public class Customer
{
    [DataMember(Name = "gors_descr")]
    public string ProductDescription { get; set; }

    [DataMember(Name = "b_name_first")]
    public string Fname { get; set; }

    [DataMember(Name = "b_name_last")]
    public string Lname { get; set; }
}

To be able to use Data attributes you will need to choose some other JSON serializer. For example DataContractJsonSerializer or Json.NET(I will use it in this example).

Customer customer = new Customer
{
    ProductDescription = tbDescription.Text,
    Fname = tbFName.Text,
    Lname = tbLName.Text
};

string creditApplicationJson = JsonConvert.SerializeObject(
    new
    {
        jsonCreditApplication = customer
    });

So jsonCreditApplication variable will be:

{
  "jsonCreditApplication": {
    "gors_descr": "Appliances",
    "b_name_first": "Marisol",
    "b_name_last": "Testcase"
  }
}

How to convert C# class object to json?

I believe you are new to this and want a working sample to kick off the work.

Here you go.

using System;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
                    
public class Program
{
    public static void Main()
    {
        var o = new UserResponse();
        o.Age = "25";
        o.Gender = "Male";
        o.Message = "Hello";
        o.UserInfo = new User();
        o.UserInfo.Id = 1;
        o.UserInfo.FirstName = "John";
        o.UserInfo.LastName = "Doe";
        o.UserInfo.Balance = 1000M;
        var json = JsonConvert.SerializeObject(o, Formatting.Indented, new JsonSerializerSettings {ContractResolver = new CamelCasePropertyNamesContractResolver()}  );
        Console.WriteLine(json);
    }
}

public class User
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName{ get; set; }
        public decimal Balance { get; set; }
    }

public class UserResponse
    {
        public User UserInfo { get; set; }
        public string Age { get; set; }
        public string Gender { get; set; }
        public string Message { get; set; }
    }

Try it out here...

Sample Code

Convert C# class to Json with customized structure

As you have tagged your question with json.net, you can do this by applying a custom JsonConverter to the "selected attributes" that should be nested inside a {"value" : ... } object when serialized.

First, define the following converter:

public class NestedValueConverter<T> : JsonConverter
{
    class Value
    {
        public T value { get; set; }
    }

    public override bool CanConvert(Type objectType)
    {
        throw new NotImplementedException();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        switch (reader.MoveToContent().TokenType)
        {
            case JsonToken.Null:
                return null;

            default:
                return serializer.Deserialize<Value>(reader).value;
        }
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        serializer.Serialize(writer, new Value { value = (T)value });
    }
}

public static partial class JsonExtensions
{
    public static JsonReader MoveToContent(this JsonReader reader)
    {
        if (reader.TokenType == JsonToken.None)
            reader.Read();
        while (reader.TokenType == JsonToken.Comment && reader.Read())
            ;
        return reader;
    }
}

Now, apply it the "selected attributes" of PrimaryContact as follows:

public class PrimaryContact
{
    [JsonConverter(typeof(NestedValueConverter<string>))]
    public string PrefixTitle { get; set; }

    public string SurName { get; set; }

    public string GivenName { get; set; }
}

And you will be able to deserialize and serialize as follows:

var settings = new JsonSerializerSettings
{
    ContractResolver = new CamelCasePropertyNamesContractResolver(),
};
var root = JsonConvert.DeserializeObject<RootObject>(jsonString, settings);

var json2 = JsonConvert.SerializeObject(root, Formatting.Indented, settings);

Notes:

• As the converter is intended to be applied directly using the attributes [JsonConverter(typeof(NestedValueConverter<...>))] or [JsonProperty(ItemConverterType = typeof(NestedValueConverter<...>))], CanConvert, which is only called when the converter is included in settings, is not implemented.

• The converter is generic in case you need to nest non-string values.

Sample fiddle here.

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