fix: django 5's choice widget is not lazy (#7707)

* Support for Django 5.0 * Fix: test.yml and django Promise handling * Shorten github action names * Update test.yml * Update _cms.scss * Update setup.py * Fix: Django 5 choice widget is not lazy either * Add test * Fix: Swapped underscore * Deprecate SuperLazyIterator and LazyChoiceField
django-cms · fsbraun · Dec 21, 2023 · Sep 22, 2023 · Nov 30, 2023 · Dec 20, 2023
commit 40c93b53a036d7ad5942a16cd273033fc7ba10d0
diff --git a/cms/forms/fields.py b/cms/forms/fields.py
@@ -1,16 +1,22 @@
+import warnings
+
 from django import forms
 from django.contrib.admin.widgets import RelatedFieldWidgetWrapper
 from django.core.validators import EMPTY_VALUES
+from django.forms import ChoiceField
 from django.utils.translation import gettext_lazy as _
 
 from cms.forms.utils import get_page_choices, get_site_choices
 from cms.forms.validators import validate_url_extra
 from cms.forms.widgets import PageSelectWidget, PageSmartLinkWidget
 from cms.models.pagemodel import Page
+from cms.utils.compat import DJANGO_4_2
 
 
 class SuperLazyIterator:
     def __init__(self, func):
+        warnings.warn("SuperLazyIterator is deprecated.",
+                      DeprecationWarning, stacklevel=2)
         self.func = func
 
     def __iter__(self):
@@ -19,14 +25,23 @@ def __iter__(self):
 
 class LazyChoiceField(forms.ChoiceField):
 
+    def __init__(self, *args, **kwargs):
+        warnings.warn("LazyChoiceField is deprecated. Use Django's ChoiceField instead.",
+                      DeprecationWarning, stacklevel=2)
+        super().__init__(*args, **kwargs)
+
     @property
     def choices(self):
         return super().choices()
 
     @choices.setter
-    def _set_choices(self, value):
-        # we overwrite this function so no list(value) is called
-        self._choices = self.widget.choices = value
+    def choices(self, value):
+        # we overwrite this function so no list(value) or normalize_choices(value) is called
+        # also, do not call the widget's setter as of Django 5
+        if DJANGO_4_2:
+            self._choices = self.widget.choices = value
+        else:
+            self._choices = self.widget._choices = value
 
 
 class PageSelectFormField(forms.MultiValueField):
@@ -42,14 +57,12 @@ def __init__(self, queryset=None, empty_label="---------", cache_choices=False,
         errors = self.default_error_messages.copy()
         if 'error_messages' in kwargs:
             errors.update(kwargs['error_messages'])
-        site_choices = SuperLazyIterator(get_site_choices)
-        page_choices = SuperLazyIterator(get_page_choices)
         self.limit_choices_to = limit_choices_to
         kwargs['required'] = required
         kwargs.pop('blank', None)
         fields = (
-            LazyChoiceField(choices=site_choices, required=False, error_messages={'invalid': errors['invalid_site']}),
-            LazyChoiceField(choices=page_choices, required=False, error_messages={'invalid': errors['invalid_page']}),
+            ChoiceField(choices=get_site_choices, required=False, error_messages={'invalid': errors['invalid_site']}),
+            ChoiceField(choices=get_page_choices, required=False, error_messages={'invalid': errors['invalid_page']}),
         )
         super().__init__(fields, *args, **kwargs)
 

diff --git a/cms/tests/test_forms.py b/cms/tests/test_forms.py
@@ -238,6 +238,17 @@ def test_superlazy_iterator_behaves_properly_for_pages(self):
 
         self.assertEqual(normal_result, list(lazy_result))
 
+    def test_lazy_choice_field_behaves_properly(self):
+        """Ensure LazyChoiceField is really lazy"""
+        choices_called = False
+        def get_choices():
+            nonlocal choices_called
+            choices_called = True
+            return ("", "-----"),
+
+        LazyChoiceField(choices=SuperLazyIterator(get_choices))
+        self.assertFalse(choices_called, "Lazy choice function called")
+
 
 class PermissionFormTestCase(CMSTestCase):