RestSharp updating use of AddHandler mathod to use factory delegate

Question

The latest version of RestSharp v106.6.9 apparently makes some changes making the overrides of the AddHandler method of a Request obsolete such as this signature:

[Obsolete("Use the overload that accepts a factory delegate")]
public void AddHandler(IDeserializer deserializer, params string[] contentTypes)

As it suggest to use the factory delegate form

public void AddHandler(string contentType, Func<IDeserializer> deserializerFactory)

public void AddHandler(Func<IDeserializer> deserializerFactory, params string[] contentTypes)

Would anyone be able to point me to an example of implementing this. Or explain how to transform my use of a customSerializer implementing IDeserializer below, to a factory delegate:

RestClient.AddHandler("application/json", CustomJsonSerializer.Instance);


public class CustomJsonSerializer : IDeserializer
{
    public static CustomJsonSerializer Instance => new CustomJsonSerializer();

    public string ContentType
    {
        get => "application/json";
        set { } // maybe used for Serialization?
    }

    public string DateFormat { get; set; }

    public string Namespace { get; set; }

    public string RootElement { get; set; }

    public T Deserialize<T>(IRestResponse response) => RestSharpResponseHandlers.DeserializeObject<T>(response);
}

Answer 1

According to the source code at https://github.com/restsharp/RestSharp/blob/dev/src/RestSharp/RestClient.cs:

 [Obsolete("Use the overload that accepts a factory delegate")]
 public void AddHandler(string contentType, IDeserializer deserializer) =>
    AddHandler(contentType, () => deserializer);

The obsolete overload just calls the AddHandler(string contentType, Func<IDeserializer> deserializerFactory) overload.

So you can replace your code to add your custom handler as follows:

RestClient.AddHandler("application/json", () => { return CustomJsonSerializer.Instance; });

Answer 2

I ran into the same problem. It looks like the OpenAPI code is setting mulitple handlers for multiple context types, so I wrote this little function

        private void AddHandlerHelper(RestClient client, IDeserializer deserializerFactory, string[] contextTypes)
        {
            foreach( var contextType in contextTypes)
            client.AddHandler(contextType,() => deserializerFactory);
        }

And the the call changes from this:

client.AddHandler(() => existingDeserializer, "application/json", "text/json", "text/x-json", "text/javascript", "*+json");

to this

AddHandlerHelper(client, existingDeserializer, new string[] { "application/json", "text/json", "text/x-json", "text/javascript", "*+json"});

There are six places in the generated code I needed the function.