RestSharp: How to skip serializing null values to JSON?

An alternative, you can use other json libraries (json.net, servicestack.text, etc.) which support ignoring null values to serialize it first:

RestRequest request = new RestRequest();...string jsonString = ThirdPartySerialization(jsonObject);request.AddParameter("application/json", jsonString, ParameterType.RequestBody);

You can use a custom IJsonSerializerStrategy together with the default SimpleJson JSON serializer to ignore null values.

The easiest way to do it is to extend the PocoJsonSerializerStrategy like below.

public class IgnoreNullValuesJsonSerializerStrategy : PocoJsonSerializerStrategy{    protected override bool TrySerializeUnknownTypes(object input, out object output)    {        bool returnValue = base.TrySerializeUnknownTypes(input, out output);        if (output is IDictionary<string, object> obj)        {            output = obj.Where(o => o.Value != null).ToDictionary(o => o.Key, o => o.Value);        }        return returnValue;    }}

And then use it as the default serializer strategy.

SimpleJson.CurrentJsonSerializerStrategy = new IgnoreNullValuesJsonSerializerStrategy();

Here is a link to a version that has been modified to ignore null values. You just need to set the serializer options to ignore nulls.

Restsharp that ignores null values