How should I serialize JSON from Refit in an F# project?

Question

I'm using Refit in a C# project to create an API client. I'd prefer to do everything with F# but Refit doesn't fully support F# yet.

If I create my User model in C# everything is fine but I'd prefer to be able to express which properties are optional and handle them appropriately.

If I add FSharp.Core and use FSharpOption<string> or similar then assertions that try to access those members fail with a NullReferenceException but only if the JSON response contains something optional.

If I create a separate F# project that contains a User model I always get a NullReferenceException when trying to deserialize.

Admittedly, keeping any models as part of the C# project seems easier but I don't want to sacrifice knowing which members are optional on the F# side.

What is the best way to go about this?

Answer 1

My current thinking is to leave the C# project as-is and create an F# wrapper which returns models in a Result type, with optional members where appropriate.

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Update:

I ended up doing this and adding the following to my FSharp models:

static member ToCSharp :
    user: User
       -> CSharp.User

static member FromCSharp :
    user: CSharp.User
       -> User option