Building complex QuerySets to recommend similar posts

Module03/mysite/blog/templates/blog/post/detail.html

@@ -13,6 +13,18 @@ <h1>{{ post.title }}</h1>
             Share this post
         </a>
     </p>
+
+
+    <h2>Similar posts</h2>
+    {% for post in similar_posts %}
+        <p>
+            <a href="{{ post.get_absolute_url }}">{{ post.title }}</a>
+        </p>
+    {% empty %}
+        There are no similar posts yet.
+    {% endfor %}
+
+
     {% with comments.count as total_comments %}
         <h2>
             {{ total_comments }} comment{{ total_comments|pluralize }}

Module03/mysite/blog/views.py

@@ -6,6 +6,7 @@
 from django.core.mail import send_mail
 from django.views.decorators.http import require_POST
 from taggit.models import Tag
+from django.db.models import Count
 
 def post_list(request, tag_slug=None):
     post_list = Post.objects.all()
@@ -46,7 +47,12 @@ def post_detail(request, year, month, day, post):
     comments = post.comments.filter(active=True)
     # Form for users to comment
     form = CommentForm()
-    return render(request, 'blog/post/detail.html', {'post': post, 'comments': comments, 'form': form})
+
+    # List of similar posts
+    post_tags_ids = post.tags.values_list('id', flat=True)
+    similar_posts = Post.objects.filter(tags__in=post_tags_ids).exclude(id=post.id)
+    similar_posts = similar_posts.annotate(same_tags=Count('tags')).order_by('-same_tags','-publish')
+    return render(request, 'blog/post/detail.html', {'post': post, 'comments': comments, 'form': form, 'similar_posts': similar_posts})
 
 def post_share(request, post_id):
     # Retrieve post by id