SAFE-Dojo Update function.fs

/// The update function knows how to update the model given a message.
let update msg model =
    match model, msg with
    | { ValidationError = None; Postcode = postcode }, GetReport ->
        { model with ServerState = Loading }, Cmd.ofPromise getResponse postcode GotReport ErrorMsg
    | _, GetReport -> model, Cmd.none
    | _, GotReport response ->
        { model with
            ValidationError = None
            Report = Some response
            ServerState = Idle }, Cmd.none
    | _, PostcodeChanged p ->
        let p = p.ToUpper()
        let validationError p =
            match Validation.validatePostcode p with
            | true -> None
            | _ -> Some "INvalid Postal Code"
        { model with
            Postcode = p
            (* Task 2.2 Validation. Use the Validation.validatePostcode function to implement client-side form validation.
               Note that the validation is the same shared code that runs on the server! *)

            ValidationError = validationError(p) }, Cmd.none
    | _, ErrorMsg e -> { model with ServerState = ServerError e.Message }, Cmd.none