sg101: gpp/news/utils.py comparison

Fixing #193; reduce news query counts by grabbing tags and comment counts in bulk. Increased news items per page from 5 to 10.

comparison

equal deleted inserted replaced

-:701730b2fcda
+:24f1230f3ee3
+"""
+Common utility/helper code for the news app.
+"""
+from django.contrib.contenttypes.models import ContentType
+from comments.models import Comment
+from tagging.models import TaggedItem
+from news.models import Story
+def attach_extra_attrs(stories):
+"""
+For each story in the input stories list, attach 2 new attributes:
+tag_list and comment_count. The tags and comment count info is pulled from
+the database in bulk. This saves database queries when lots of news
+stories are displayed at once. For best results, use ".defer('tags')"
+when retrieve the stories from the database.
+"""
+stories_dict = dict((story.id, story) for story in stories)
+story_ids = stories_dict.keys()
+# Get all the tags out in one query
+ct = ContentType.objects.get_for_model(Story)
+tagged_items = TaggedItem.objects.filter(content_type=ct,
+object_id__in=story_ids).select_related('tag')
+for story in stories_dict.values():
+story.tag_list = []
+story.comment_count = 0
+# attach tags
+for item in tagged_items:
+stories_dict[item.object_id].tag_list.append(item.tag.name)
+# Now get all the comment counts out in one fell swoop
+story_ids = Comment.objects.filter(content_type=ct,
+object_id__in=story_ids).values_list('object_id', flat=True)
+# compute comment_count
+for story_id in story_ids:
+stories_dict[story_id].comment_count += 1

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