Nest 2.x - Custom JsonConverter - elasticsearch

Question

I want to use the IsoDateTimeConverter from Newtonsoft to format the json version of my DateTime properties.
However, I cant figure out how this is done in Nest 2.x.
Here is my code:
var connectionPool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
var settings = new ConnectionSettings(connectionPool, s => new MyJsonNetSerializer(s));
var client = new ElasticClient(settings);
public class MyJsonNetSerializer : JsonNetSerializer
{
public MyJsonNetSerializer(IConnectionSettingsValues settings) : base(settings) { }
protected override void ModifyJsonSerializerSettings(JsonSerializerSettings settings)
{
settings.NullValueHandling = NullValueHandling.Ignore;
}
protected override IList<Func<Type, JsonConverter>> ContractConverters => new List<Func<Type, JsonConverter>>()
{
type => new Newtonsoft.Json.Converters.IsoDateTimeConverter()
};
}
I'm getting this exception:
message: "An error has occurred.",
exceptionMessage: "Unexpected value when converting date. Expected DateTime or DateTimeOffset, got Nest.SearchDescriptor`1[TestProject.DemoProduct].",
exceptionType: "Elasticsearch.Net.UnexpectedElasticsearchClientException"
Any help is appreciated

Answer 1

with the Func<Type, JsonConverter>, you need to check that the type is the right one for the converter that you want to register; if it is, return the converter instance, otherwise return null
public class MyJsonNetSerializer : JsonNetSerializer
{
public MyJsonNetSerializer(IConnectionSettingsValues settings) : base(settings) { }
protected override void ModifyJsonSerializerSettings(JsonSerializerSettings settings)
{
settings.NullValueHandling = NullValueHandling.Ignore;
}
protected override IList<Func<Type, JsonConverter>> ContractConverters => new List<Func<Type, JsonConverter>>()
{
type =>
{
return type == typeof(DateTime) ||
type == typeof(DateTimeOffset) ||
type == typeof(DateTime?) ||
type == typeof(DateTimeOffset?)
? new Newtonsoft.Json.Converters.IsoDateTimeConverter()
: null;
}
};
}
NEST uses the IsoDateTimeConverter for those types by default, so you won't need to register a converter for them unless you would like to change other settings on the converter.