Form values with type bool always interpreted as true

[OnkV]

My System:

• Debian 12
• OCaml 5.2.1
• Ocsigenserver 6.0.0
• Eliom 11.1.1

This code creates a form which toggles a boolean value (stored in a reference):

(*** Services ***)

let%server test_service =
  let open Eliom_service in
  create ~path:(Path ["test"]) ~meth:(Get Eliom_parameter.unit) ()

let%client test_service = ~%test_service

let%server redir_to_test_service =
  let open Eliom_service in
  create ~path:(Path ["redir_to_test"])
    ~meth:(Get Eliom_parameter.unit) ()

let%client redir_to_test_service = ~%redir_to_test_service

let%server test_form_service =
  let open Eliom_service in
  create_attached_post
    ~fallback:redir_to_test_service
    ~post_params:(Eliom_parameter.(bool "bool_value")) ()

let%client test_form_service = ~%test_form_service

(*** References ***)

let persistent = ...

let%server ref_bool_test : bool Eliom_reference.eref =
  Eliom_reference.eref ~persistent
    ~scope:Eliom_common.default_session_scope
    false

let%rpc set_ref_bool_test (value:bool) =
  Eliom_reference.set ref_bool_test value

let%rpc get_ref_bool_test () =
  Eliom_reference.get ref_bool_test

(*** Handlers ***)

let%shared redir_to_test_handler () () =
  Lwt.return (Eliom_registration.Redirection test_service)

let%shared test_form next_bool_value =
  let open Eliom_content.Html.F in
  let button_value = if next_bool_value then "-> true" else "-> false" in
  Form.post_form ~service:test_form_service
    (fun next_bool_param -> [
         Form.input ~input_type:`Hidden ~name:next_bool_param
           ~value:next_bool_value Form.bool;
         Form.input ~input_type:`Submit ~value:button_value Form.string]) ()

let%shared test_form_handler () next_bool_value =
  set_ref_bool_test next_bool_value

let%shared test_handler () () =
  let open Eliom_content.Html.F in
  let%lwt curr_bool_value = get_ref_bool_test () in
  let next_bool_value = not curr_bool_value in
  Lwt.return (html (head (title (txt "Test")) [])
                (body [h1 [txt "Test"];
                       txt ("current bool value: " ^
                            (string_of_bool curr_bool_value));
                       (test_form next_bool_value)]))

(*** Registration ***)

module%shared Test_app =
  Eliom_registration.App (struct
    let application_name = application_name
    let global_data_path = Some ["__global_data__"]
  end)

let%shared () =
  let open Eliom_registration in
  Test_app.register ~service:test_service test_handler ;
  Redirection.register ~service:redir_to_test_service redir_to_test_handler ;
  Action.register ~service:test_form_service test_form_handler 

I hope you don't mind the elaborate example code.

The HTML generated from the form looks fine. It includes a hidden input field with the correct boolean value - but the form handler always receives true.