Improved efficiency of rendering plugins embedded in text plugins usi…

…ng bulk queries

This reduces the rendering of a text plugin with N embedded plugins from 3N
+ 1 queries to 3 queries.

cms/models/pluginmodel.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import itertools
 import os
 import warnings
 from datetime import datetime, date
@@ -61,8 +62,35 @@ def __new__(cls, name, bases, attrs):
             new_class._meta.db_table = table_name
 
         return new_class
-
-
+
+
+class CMSPluginManager(models.Manager):
+    def bulk_get(self, ids, with_instances=True, select_placeholder=True):
+        """
+        Retrieve a set of CMSPlugin objects, with their plugin model instances,
+        efficiently, and a return as dictionary of {pk:CMSPlugin object}.
+        """
+        from cms.plugin_pool import plugin_pool
+        objs = list(self.get_query_set().filter(id__in=ids))
+        retval = dict([(o.id, o) for o in objs])
+        if with_instances:
+            # group according to plugin_type, and retrieve the child objects in
+            # batches.
+            for plugin_type, parents in itertools.groupby(objs, lambda o: o.plugin_type):
+                parents = list(parents)
+                plugin_class = plugin_pool.get_plugin(parents[0].plugin_type)
+                q = plugin_class.model.objects.filter(id__in=[o.id for o in parents])
+                if select_placeholder:
+                    q = q.select_related('placeholder')
+                children = list(q)
+                # Now match them up
+                children_parent_dict = dict([(o.cmsplugin_ptr_id, o) for o in children])
+                for parent in parents:
+                    child = children_parent_dict[parent.id]
+                    parent._instance = child
+        return retval
+
+
 class CMSPlugin(MPTTModel):
     '''
     The base class for a CMS plugin model. When defining a new custom plugin, you should
@@ -88,7 +116,9 @@ class CMSPlugin(MPTTModel):
     lft = models.PositiveIntegerField(db_index=True, editable=False)
     rght = models.PositiveIntegerField(db_index=True, editable=False)
     tree_id = models.PositiveIntegerField(db_index=True, editable=False)
-
+
+    objects = CMSPluginManager()
+
     class Meta:
         app_label = 'cms'
 
@@ -151,6 +181,10 @@ def get_plugin_instance(self, admin=None):
         from cms.plugin_pool import plugin_pool
         plugin_class = plugin_pool.get_plugin(self.plugin_type)
         plugin = plugin_class(plugin_class.model, admin)# needed so we have the same signature as the original ModelAdmin
+
+        if hasattr(self, '_instance'):
+            return self._instance, plugin
+
         if plugin.model != self.__class__: # and self.__class__ == CMSPlugin:
             # (if self is actually a subclass, getattr below would break)
             try:

cms/plugins/text/utils.py

@@ -38,12 +38,19 @@ def plugin_tags_to_user_html(text, context, placeholder):
 
     context is the template context to use, placeholder is the placeholder name
     """
+    # Collect all the objects at once to minimize DB queries
+    plugin_ids = map(int, set(OBJ_ADMIN_RE.findall(text)))
+    plugin_objs = CMSPlugin.objects.bulk_get(plugin_ids,
+                                             with_instances=True,
+                                             select_placeholder=True)
+
+    # Now render and subsitute
     def _render_tag(m):
         plugin_id = int(m.groups()[0])
         try:
-            obj = CMSPlugin.objects.get(pk=plugin_id)
+            obj = plugin_objs[plugin_id]
             obj._render_meta.text_enabled = True
-        except CMSPlugin.DoesNotExist:
+        except KeyError:
             # Object must have been deleted.  It cannot be rendered to
             # end user so just remove it from the HTML altogether
             return u''

cms/tests/plugins.py

@@ -336,6 +336,33 @@ def test_inheritplugin_media(self):
             response = self.client.get(page.get_absolute_url())
             self.assertTrue('%scms/js/libs/jquery.tweet.js' % settings.STATIC_URL in response.content, response.content)
 
+    def test_render_textplugin(self):
+        # Setup
+        page = create_page("render test", "nav_playground.html", "en")
+        ph = page.placeholders.get(slot="body")
+        text_plugin = add_plugin(ph, "TextPlugin", "en", body="Hello World")
+        link_plugins = []
+        for i in range(0, 10):
+            link_plugins.append(add_plugin(ph, "LinkPlugin", "en",
+                                           target=text_plugin,
+                                           name="A Link",
+                                           url="http://django-cms.org"))
+        txt = text_plugin.text
+        txt.body = plugin_tags_to_admin_html(
+            '\n'.join(["{{ plugin_object %d }}" % l.cmsplugin_ptr_id
+                       for l in link_plugins]))
+        txt.save()
+        text_plugin = self.reload(text_plugin)
+
+        # 1 query for Placeholder object (could be eliminated with select_related
+        #   in the right place)
+        # 1 query for the CMSPlugin objects,
+        # 1 query for each type of child object (1 in this case, all are Link)
+        with self.assertNumQueries(3):
+            rendered = text_plugin.render_plugin(placeholder=ph)
+
+        self.assertTrue('A Link' in rendered)
+
     def test_copy_textplugin(self):
         """
         Test that copying of textplugins replaces references to copied plugins