Input widget bound to a page variable: MDL cannot write it (MDL-WIDGET34) and DESCRIBE PAGE silently drops the binding

[kaspergff]

Environment: mxcli nightly-20260927-95091765 (2026-09-27T08:03:29Z), Mendix 11.12.1, Windows 11.

Summary: An input widget (checkbox, text box, …) bound directly to a page variable (Forms$PageVariable.LocalVariable) cannot be expressed in MDL, on either the write or the read side. On read, DESCRIBE drops the binding silently, so a DESCRIBE → exec round-trip turns a bound widget into an unbound one without any warning.

This is the input-widget counterpart of #977 (ContentParams bound to a page variable) and #565 (DESCRIBE of a ClientTemplateParameter bound to a page variable).

Steps to reproduce — write side

create or replace page MyModule.Order_Overview (
  Title: 'Orders',
  Layout: Atlas_Core.Atlas_Default,
  Variables: { $ShowAll: Boolean = 'true' }
) {
  checkbox cbShowAll (Label: 'Show all', Attribute: $ShowAll)
}

Actual (mxcli check)

checkbox `cbShowAll`: `Attribute: $ShowAll` is not an attribute binding MDL can store — the widget would be written with no binding at all, inside a data view or outside one. [...] [MDL-WIDGET34]

Steps to reproduce — read side

1. In Studio Pro, create a page with a Boolean page variable ShowAll and a checkbox whose value is bound to that page variable.
2. mxcli describe page MyModule.Order_Overview

Actual: the checkbox is printed as checkbox checkBox1 (Label: 'Show all'): no binding, no comment, no warning. mxcli bson dump --type page does contain the binding (Forms$PageVariable with LocalVariable: "ShowAll"). Executing the DESCRIBE output writes an unbound checkbox.

Expected

• Write: Attribute: $ShowAll (or a dedicated keyword) on an input widget writes the page-variable binding.
• Read: DESCRIBE prints that same form. At minimum, until writing is supported, DESCRIBE should emit a warning/comment that the widget has a page-variable binding MDL cannot represent, so a round-trip is not silently lossy.

Workaround: a non-persistent helper entity with a data view around the widget.

[github-actions]

Issue Triage

Summary:
The issue reports that mxcli cannot write or read MDL bindings of input widgets to page variables, causing silent loss of the binding during a DESCRIBE → exec round‑trip.

Checklist (bug‑report requirements)

Required info	Present?	Details
mxcli version	✅	nightly-20260927-95091765 (2026-09-27T08:03:29Z)
Mendix version	✅	11.12.1
Scenario (what the user was trying to do)	✅	MDL script creating a page with a checkbox bound to a page variable; mxcli describe page command
Expected output	✅	Binding should be preserved (or at least warned about) when writing/reading MDL
Experienced output	✅	Write side: MDL‑WIDGET34 error; Read side: binding omitted silently, no warning
AI bug report (mxcli diag --bundle or session log)	❌	Not included

What’s missing:
To help diagnose the issue, could you please provide the output of mxcli diag --bundle (or at least the relevant session log) for the commands that triggered the problem? This will give us the internal context needed to investigate further.

Thank you for the detailed report! Once we have the diagnostic bundle, we’ll be able to look into the binding handling.

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