fix: prefix_default_language = False redirect behavior fixes (#6851)

* make is_language_prefix_patterns_used check for non-empty language_prefix insted of doing isinstance check on pattern only
* if prefix patterns are used get_language_from_request normally, otherwise default
* updated CHANGELOG
* remove previous details request_language change and replace it with page model cache workaround
* fix tests
* if prefix patterns are used get_language_from_request normally, otherwise default
* add language check workaround to menus as well

Co-authored-by: Radosław Stępień <rstepien@cloudferro.com>
Co-authored-by: Florian Delizy <florian.delizy@gmail.com>

CHANGELOG.rst

@@ -2,6 +2,11 @@
 Changelog
 =========
 
+Unreleased
+==================
+
+* Fixed redirect issues when i18n_patterns had prefix_default_language = False
+
 
 Unreleased
 ==================

cms/utils/i18n.py

@@ -193,16 +193,16 @@ def hide_untranslated(language, site_id=None):
 
 def is_language_prefix_patterns_used():
     """
-    Returns `True` if the `LocaleRegexURLResolver` or `LocalePrefixPattern` is
-    used at root level of the urlpatterns, else it returns `False`.
-    """
-    return any(
-        isinstance(
-            getattr(url_pattern, 'pattern', url_pattern),
-            LocalePrefixPattern
-        )
-        for url_pattern in get_resolver(None).url_patterns
-    )
+    Returns `True` if the `LocaleRegexURLResolver` or `LocalePrefixPattern` 
+    is used at root level of the urlpatterns and doesn't have empty 
+    language_prefix, else it returns `False`.
+    """
+    for url_pattern in get_resolver(None).url_patterns:
+        pattern = getattr(url_pattern, 'pattern', url_pattern)
+        if isinstance(pattern, LocalePrefixPattern):
+            if pattern.language_prefix != '':
+                return True
+    return False
 
 
 def is_valid_site_language(language, site_id):

cms/views.py

@@ -86,7 +86,10 @@ def details(request, slug):
     else:
         user_languages = get_public_languages(site_id=site.pk)
 
-    request_language = get_language_from_request(request, check_path=True)
+    if is_language_prefix_patterns_used():
+        request_language = get_language_from_request(request, check_path=True)
+    else:
+        request_language = get_default_language_for_site(site.pk)
 
     if not page.is_home and request_language not in user_languages:
         # The homepage is treated differently because

menus/menu_pool.py

@@ -9,7 +9,9 @@
 from django.utils.functional import cached_property
 from django.utils.module_loading import autodiscover_modules
 from django.utils.translation import get_language_from_request, gettext_lazy as _
-
+from cms.utils import get_current_site
+from cms.utils.i18n import (get_default_language_for_site,
+                        is_language_prefix_patterns_used)
 from cms.utils.conf import get_cms_setting
 from cms.utils.moderator import use_draft
 
@@ -101,7 +103,10 @@ def __init__(self, pool, request):
         # instance lives.
         self.menus = pool.get_registered_menus(for_rendering=True)
         self.request = request
-        self.request_language = get_language_from_request(request, check_path=True)
+        if is_language_prefix_patterns_used():
+            self.request_language = get_language_from_request(request, check_path=True)
+        else:
+            self.request_language = get_default_language_for_site(get_current_site().pk)
         self.site = Site.objects.get_current(request)
 
     @property