F# class serialization: mutable fields within F# records are duped with @ suffix

[nodakai]

Library Version

4.23.0

OS

macOS 14.6.1 (23G93)

OS Architecture

64 bit

How to reproduce?

module Main

open System.IO
open Parquet.Serialization

[<CLIMutable>]
type Foo = {
  mutable A: int
  B: float
}

let [<EntryPoint>] main _ =
  task {
    use f = File.Create "test.parquet"
    let! sch = ParquetSerializer.SerializeAsync([|{A=1; B=1.}|], f)
    printfn $"schema:\n%O{sch}"
    return 0
  } |> _.GetAwaiter().GetResult()

<= 4.22.1

schema:
A (System.Int32)
B (System.Double)

>= 4.23.0

schema:
A (System.Int32)
B (System.Double)
A@ (System.Int32)

The columns A and A@ contain duplicated data. The latter seems to come from .field public int32 A@ according to Rider's IL viewer.

% dotnet --version
8.0.401

Failing test

No response

[nodakai]

Hmm maybe F# shouldn't have defined the backing field as public...

Is it possible to add a new field, sth like PropertiesOnly to ParquetSerializerOptions to restore the pre 4.23 behavior?
I can't seem to apply JsonIgnore to the F# compiler-generated backing fields.

[aloneguid]

Thanks, I need to think about how to do this without impacting performance, as type info is cached at the moment and not discovered on every deserialisation call.

In the meantime you could do something like this:

type Foo = 
    val mutable private _a: int
    val B: float

    member this.A
        with get() = this._a
        and set(value) = this._a <- value