Fix: Version 3 import

Author: fsbraun

README.rst

@@ -4,16 +4,19 @@
 
 |pypi| |docs| |coverage| |python| |django| |djangocms| |djangocms4|
 
-**django CMS Frontend** is a plugin bundle which builds on and improves
+**django CMS Frontend** is a plugin bundle which originally built on and improved
 the architecture of `djangocms-bootstrap4 <https://github.com/django-cms/djangocms-bootstrap4>`_.
-Its objective is to provide a set of popular frontend components independent of the
-currently used frontend framework such as Bootstrap, or its specific version.
+Its objective is to provide a toolset to quickly create re-usable frontend
+components and comes preloaded with a set of popular frontend components
+independent of the currently used frontend framework such as Bootstrap, or
+its specific version.
 
 .. image:: preview.png
 
 Key features
 ============
 
+- Easy to implement re-usable frontend custom components.
 - Support of `Bootstrap 5 <https://getbootstrap.com>`_, django CMS 3.8+
   and django CMS 4.
 

djangocms_frontend/ui_plugin_base.py

@@ -1,17 +1,22 @@
-from cms.admin.placeholderadmin import PlaceholderAdmin
 from cms.plugin_base import CMSPluginBase
 
 # Import the components from the current directory's models module
 from django.utils.encoding import force_str
 
 from djangocms_frontend.helpers import get_related
 
-if hasattr(PlaceholderAdmin, "edit_field"):
-    # FrontendEditable functionality already implemented in core?
-    class FrontendEditableAdminMixin:
-        pass
-else:
-    # If not use our own version of the plugin-enabled mixin
+try:
+    from cms.admin.placeholderadmin import PlaceholderAdmin
+
+    if hasattr(PlaceholderAdmin, "edit_field"):
+        # FrontendEditable functionality already implemented in core?
+        class FrontendEditableAdminMixin:
+            pass
+    else:
+        # If not use our own version of the plugin-enabled mixin
+        raise ImportError
+except ImportError:
+    # django CMS 3 did not implement this: use our own version of the plugin-enabled mixin
     from .helpers import FrontendEditableAdminMixin