Transferring private types

[DejanMilicic]

I have a type that looks like this:

    module DateRange = 
        type T = private
            { 
                StartDate: DateTime option
                EndDate: DateTime option
            }

When making Fable.Remoting calls, NewtonSoft.Json complains that there is not public constructor exposed.
Removing private is a quick fix.

However, is there any other way I could resolve this without exposing properties of the type? E.g. would switching to some other serialization method work? What would be your recommendation in this case?

[Zaid-Ajaj]

Hi there @DejanMilicic I haven't tested what the binary serialization does to private fields, maybe you could try that and see if it fixes the problem? Otherwise I don't think there is a way to do this right now with Newtonsoft.Json 🤔

[Larocceau]

Hi! came here with the same problem as @DejanMilicic. Just wanted to confirm that turning on binary serialization does indeed fix the issue. Thanks @Zaid-Ajaj

[randrag]

Hi @DejanMilicic, a quick note to say that private discriminated unions are successfully transferred.

I.e.,

module DateRange =
   type T = private T of {
      StartDate : Option<DateTime>
      EndDate : Option<DateTime>
}

I'm not sure whether this is by design, or by accident.

One upshot is that constrained types coming from the JS front end don't get constructed with the proper constructor, which leaves you vulnerable to exploits, since the JSON can contain illegal values, which are placed in your constrained type during deserialisation.

We have toyed with the idea of implementing a ReWrap () or similar method on these types, which would apply the business rules to make sure that the constrained type is valid, and adding Fable remoting option to allow us to call this method using reflection invoke if it exists. @Zaid-Ajaj does this seem like a reasonable addition to the library?

Roland