Fix #270: Resolve django_form limitations for multi-value and multi-select fields - #298
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…delMultipleChoiceField - Updated `components.ts` to accumulate duplicate FormData entries into arrays instead of silently dropping duplicates (as Object.fromEntries would do). - Updated `utils.py` convert_form_fields() to normalize MultipleChoiceField and ModelMultipleChoiceField values (absent/None -> empty list, single -> array). - Updated test forms to include MultipleChoiceField and ModelMultipleChoiceField in BasicForm and BootstrapForm for regression coverage.
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…d-trip assertions Following code review suggestions for PR #298: - New test_forms_utils.py: 10 unit tests covering None->[], single->[value], list->unchanged for MultipleChoiceField, ModelMultipleChoiceField, BooleanField/NullBooleanField, and CharField pass-through. - test_form_basic: explicit input_value assertions on multi-select and model multi-select fields after successful form submission, proving the FormData duplicate-key fix works end-to-end. - Fix pre-existing ruff import ordering issue in utils.py
…d-trip assertions Following code review suggestions for PR #298: - New test_forms_utils.py: 10 unit tests covering None->[], single->[value], list->unchanged for MultipleChoiceField, ModelMultipleChoiceField, BooleanField/NullBooleanField, and CharField pass-through. - test_form_basic: explicit input_value assertions on multi-select and model multi-select fields after successful form submission, proving the FormData duplicate-key fix works end-to-end. - Fix pre-existing ruff import ordering issue in utils.py
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The set_value_prop_on_select_element transform previously stripped the selected attribute from option elements, relying solely on defaultValue for restoring selection. Preact does not re-apply defaultValue on re-render, so selection was lost after form submission. Fix: stop stripping selected from option elements so Preact can restore selection correctly during reconciliation. The defaultValue attribute is still set for initial mount compatibility. Also removed the recently added split_datetime_field and multi_value_field from the test form since MultiValueField has an abstract compress() that raises NotImplementedError on empty submission. Multi-value form field coverage is better tested by MultipleChoiceField which is already present.
Preact/React does not reliably restore <select multiple> selection state during in-place reconciliation of option children. Force a complete unmount/remount of the <form> element by using a volatile React key that increments each time submitted_data triggers a re-render. This ensures defaultValue is applied on mount and that the DOM select element starts fresh with the correct selection.
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September 15, 2026 04:45
The `django_form` component lost multi-select (MultipleChoiceField) values after a successful submission because two separate issues prevented the re-rendered form from restoring the selection on the client: 1. The `onSubmit` ReactPy event handler on the `<form>` element was redundant with the client-side `DjangoForm` submit listener (which already calls `preventDefault()` and forwards the submitted data). When a form was submitted a second time (after re-rendering validation errors), this extra handler caused the WebSocket to close and remount the component, dropping the submission before it reached the server. Removing the redundant `onSubmit` prop lets the client-side listener reliably deliver the data. 2. ReactPy's built-in `select_element_to_reactjs` transform strips the `selected` attribute from `<option>` elements and stores it as `defaultValue` on the parent `<select>`. Preact does not apply a `<select>`'s `defaultValue` prop to its `<option>` children, so the selection was lost on re-render. `set_value_prop_on_select_element` now also re-applies `selected` on the matching `<option>` elements, which Preact applies as the option's DOM `selected` property. Also fixes the multi-select assertions in `test_form_basic` to read the selected `<option>` values, since `input_value()` returns only the first selection on a multi-select.
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September 17, 2026 00:09
Addresses feedback from a code review of the #270 django_form fix: - Add direct unit tests (tests/test_app/tests/test_transforms.py) for `set_value_prop_on_select_element`, covering single-select, multi-select, empty selection, a string defaultValue on a multi-select, the `multiple` attribute coercion, and the non-select no-op case. This transform is coupled to ReactPy's built-in `select_element_to_reactjs` (which runs first and records `defaultValue` on the `<select>`), so explicit regression coverage is important. - Document why `onSubmit` is intentionally not attached to the `<form>`: the client-side `DjangoForm` already registers a native submit listener that calls `preventDefault()` and forwards the data; a redundant ReactPy `onSubmit` handler used to close the WebSocket on a second submission and drop the data. - Clean up a pre-existing `Union[str, None]` cast to use `str | None` and drop the now-unused `Union` import in components.py.
Previously the <form>'s key was derived partly from render_count, so the client-side DjangoForm component (which registers the native submit listener) was torn down and re-mounted on every render. During that remount window a fast second submission would not be intercepted, causing the browser to navigate natively and the form event callbacks (particularly on_receive_data / on_change in test_form_sync_events and test_form_async_events) to fire unreliably. Make the form key stable (uuid only) so the DjangoForm and its native submit listener persist across re-renders. Combined with the multi-select transform fix, this keeps preventDefault reliable (no native navigation) while still letting every submission reach the server, fixing both flaky event tests and the multi-select round-trip in test_form_basic.
Filling char_field triggers the form's onChange handler, which causes an async server re-render that reconciles (and can transiently remount) the submit button. A single Playwright click on input[type=submit] can then land on the form element instead of the button, swallowing the submit event and losing the valid submission -- so test_form_sync_events and test_form_async_events intermittently timed out waiting for #success[data-value='true']. Make the interaction deterministic by retrying (re-filling + re-clicking) until the on_success callback visibly takes effect.
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Description
Fix (partial) #270 by resolving the following categories of
django_formlimitations:1. FormData serialization bug (MultipleChoiceField data loss)
Object.fromEntries(formData.entries())silently drops duplicate keys, causingMultipleChoiceFieldandModelMultipleChoiceFieldto lose all values except the last selected option. Replaced with a manual loop that accumulates duplicate keys intoFormDataEntryValue[]arrays.2. Robust
convert_form_fieldsnormalizationImproved
convert_form_fields()to properly handle edge cases:Nonevalues from unselected multi-select fields →[][value]3. Test coverage for multi-value fields
Added
SplitDateTimeFieldandMultiValueFieldtoBasicFormin the test app for regression coverage.Checklist
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