Supercharging Marten with the Jil Serializer

Some blog posts you write for attention or self promotion, some you write just because you’re excited about the topic, and some posts you write just to try to stick some content for later into Google searches. This one’s all about users googling for this information down the road.

Out of the box, Marten uses Newtonsoft.Json as its primary JSON serialization mechanism. While Newtonsoft has outstanding customizability and the most flexible feature set, you can opt to forgo some of that flexibility in favor of higher performance by switching instead to the Jil serializer.

In the last couple months I finally made a big effort to be able to run Marten’s test suite using the Jil serializer. I had to make one small adjustment to our JilSerializer (turning on includeInherited), and a distressingly intrusive structural change to make the internal handling of Enum values (!) in Linq queries be dependent upon the internal serializer’s behavior for enum storage.

At this point, we’re not supplying a separate Marten.Jil adapter package, but the code to swap in Jil is just this class:

public class JilSerializer : ISerializer
    private readonly Options _options 
        = new Options(dateFormat: DateTimeFormat.ISO8601, includeInherited:true);

    public string ToJson(object document)
        return JSON.Serialize(document, _options);

    public T FromJson<T>(string json)
        return JSON.Deserialize<T>(json, _options);

    public T FromJson<T>(Stream stream)
        return JSON.Deserialize<T>(new StreamReader(stream), _options);

    public object FromJson(Type type, string json)
        return JSON.Deserialize(json, type, _options);

    public string ToCleanJson(object document)
        return ToJson(document);

    public EnumStorage EnumStorage => EnumStorage.AsString;

And this one line of code in your document store set up:

var store = DocumentStore.For(_ =>
    _.Connection("the connection string");

    // Replace the ISerializer w/ the JilSerializer

A couple things to note about using Jil in place of Newtonsoft:

  • The enumeration persistence behavior is different from Newtonsoft as it stores enum values by their string representation. Most Marten users seem to prefer this anyway, but watch the value of the “EnumStorage” property in your custom serializer.
  • We’ve tried very hard with Marten to ensure that the Json stored in the database doesn’t require .Net type metadata, but the one thing we can’t address is having polymorphic child collections. For that particular use case, you’ll have to stick with Newtonsoft.Json and turn on its type metadata handling.


3 thoughts on “Supercharging Marten with the Jil Serializer

  1. You could do one of the nuget packages that just drop the code file directly out into the project.

    Potentially you could only put a readme in the package which links to a gist to copy and paste the code. I don’t know if that potentially breaks the rules of

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