Step21: number of post in category

yangxg · yangxg · commit 1438df2bab2e · 2017-06-02T14:54:43.000+08:00
diff --git a/blog/templatetags/blog_tags.py b/blog/templatetags/blog_tags.py
@@ -1,4 +1,5 @@
 from django import template
+from django.db.models.aggregates import Count
 
 from ..models import Post, Category
 
@@ -17,4 +18,5 @@ def archives():
 
 @register.simple_tag
 def get_categories():
-    return Category.objects.all()
+    # 记得在顶部引入 count 函数
+    return Category.objects.annotate(num_posts=Count('post')).filter(num_posts__gt=0)
diff --git a/templates/base.html b/templates/base.html
@@ -110,7 +110,7 @@ <h3 class="widget-title">分类</h3>
                         {% for category in category_list %}
                             <li>
                                 <a href="{% url 'blog:category' category.pk %}">{{ category.name }} <span
-                                        class="post-count">(13)</span></a>
+                                        class="post-count">({{ category.num_posts }})</span></a>
                             </li>
                         {% empty %}
                             暂无分类！
