Serialization

RestSharp has JSON and XML serializers built in.

TIP

The default behavior of RestSharp is to swallow deserialization errors and return null in the Data property of the response. Read more about it in the Error Handling.

JSON

The default JSON serializer uses System.Text.Json, which is a part of .NET since .NET 6. For earlier versions, it is added as a dependency. There are also a few serializers provided as additional packages.

XML

The default XML serializer is DotNetXmlSerializer, which uses System.Xml.Serialization library from .NET.

In previous versions of RestSharp, the default XML serializer was a custom RestSharp XML serializer. To make the code library size smaller, that serializer is now available as a separate package RestSharp.Serializers.Xmlopen in new window. You can add it back if necessary by installing the package and adding it to the client:

client.UseXmlSerializer();

As before, you can supply three optional arguments for a custom namespace, custom root element, and if you want to use SerializeAs and DeserializeAs attributed.

NewtonsoftJson (aka Json.Net)

The NewtonsoftJson package is the most popular JSON serializer for .NET. It handles all possible scenarios and is very configurable. Such a flexibility comes with the cost of performance. If you need speed, keep the default JSON serializer.

RestSharp support Json.Net serializer via a separate package RestSharp.Serializers.NewtonsoftJsonopen in new window.

WARNING

Please note that RestSharp.Newtonsoft.Json package is not provided by RestSharp, is marked as obsolete on NuGet, and no longer supported by its creator.

Use the extension method provided by the package to configure the client:

client.UseNewtonsoftJson();

The serializer configures some options by default:

JsonSerializerSettings DefaultSettings = new JsonSerializerSettings {
    ContractResolver     = new CamelCasePropertyNamesContractResolver(),
    DefaultValueHandling = DefaultValueHandling.Include,
    TypeNameHandling     = TypeNameHandling.None,
    NullValueHandling    = NullValueHandling.Ignore,
    Formatting           = Formatting.None,
    ConstructorHandling  = ConstructorHandling.AllowNonPublicDefaultConstructor
};

If you need to use different settings, you can supply your instance of JsonSerializerSettings as a parameter for the extension method.

Custom

You can also implement your custom serializer. To support both serialization and deserialization, you must implement the IRestSerializer interface.

Here is an example of a custom serializer that uses System.Text.Json:

public class SimpleJsonSerializer : IRestSerializer {
    public string Serialize(object obj) => JsonSerializer.Serialize(obj);

    public string Serialize(Parameter bodyParameter) => Serialize(bodyParameter.Value);

    public T Deserialize<T>(IRestResponse response) => JsonSerializer.Deserialize<T>(response.Content);

    public string[] SupportedContentTypes { get; } = {
        "application/json", "text/json", "text/x-json", "text/javascript", "*+json"
    };

    public string ContentType { get; set; } = "application/json";

    public DataFormat DataFormat { get; } = DataFormat.Json;
}

The value of the SupportedContentTypes property will be used to match the serializer with the response Content-Type headers.

The ContentType property will be used when making a request so the server knows how to handle the payload.