How to deserialize json property for enumeration class using Json.Net?

Question

I am trying to avoid using Enums and use enumeration classes instead such as explained here https://docs.microsoft.com/en-us/dotnet/architecture/microservices/microservice-ddd-cqrs-patterns/enumeration-classes-over-enum-types

Now I have the following example

public class Dto
{
public string Name {get;set;}
public StatusType Status {get;set;}
}

public class StatusType : Enumeration
{
public static readonly StatusType Active = new StatusType (1, "Active");
public static readonly StatusType Inactive = new StatusType (2, "Inactive");
}

When I try to deserialize Dto such as

var message = JsonConvert.DeserializeObject<Dto>(test);

I get an error 'Error converting value "Active" to type 'StatusType'.

Is it possible to use or create a converter that would actually convert value "Active" to a proper StatusType?

Answer 1

You will need to write custom JsonConverter . For example like this:

public class StatusTypeConverter : JsonConverter<StatusType>
{
    // can be build with reflection 
    private static Dictionary<string, StatusType> _map = new Dictionary<string, StatusType>(StringComparer.InvariantCultureIgnoreCase)
    {
        {StatusType.Active.Name, StatusType.Active},
        {StatusType.Inactive.Name, StatusType.Inactive}
    };
    public override void WriteJson(JsonWriter writer, StatusType value, JsonSerializer serializer)
    {
        writer.WriteValue(value.Name);
    }

    public override StatusType ReadJson(JsonReader reader, Type objectType, StatusType existingValue, bool hasExistingValue, JsonSerializer serializer)
    {
        string s = (string)reader.Value;

        return _map[s];
    }
}

public class Dto
{
    public string Name { get; set; }
    [JsonConverter(typeof(StatusTypeConverter))]
    public StatusType Status { get; set; }
}

var js = "{'name': 'Name', 'status': 'active'}";
Console.WriteLine(JsonConvert.DeserializeObject<Dto>(js).Status.Name); // prints "Active"

This code obviously can be improved(meaningful exception for missing keys, building converter which can handle all subtypes of Enumeration with help of reflection).