我正在使用django和redis来构建排名应用程序，项目分数存储在一个排序集中，其密钥为“ranking：id：item_rank”。 Django-debug-toolbar表示当我在索引页面中显示排名及其前三项时，SQL查询会有重复。
＃models.py
class Ranking(models.Model):
title = models.CharField(max_length=16, unique=True)
class Item(models.Model):
title = models.CharField(max_length=128)
ranking = models.ForeignKey(Ranking, related_name='items')
＃views.py
def index(request):
rankings = Ranking.objects.all()
return render(request, 'myapp/index.html', {'rankings': rankings})
我创建自定义模板标签以显示索引页面中的前三项。
＃templatetags / ranking_tags.py
r = redis.StrictRedis(host=settings.REDIS_HOST,
port=settings.REDIS_PORT,
db=settings.REDIS_DB)
@register.assignment_tag
def get_top_3(ranking):
item_rank = r.zrange('ranking:{}:item_rank'.format(ranking.id), 0, 2, desc=True)
item_ids = [int(id) for id in item_rank]
items = list(Item.objects.filter(id__in=item_ids))
text = ''
try:
text = '<p>#1 :' + items[0].title + '</p>'
text = text + '<p>#2 :' + items[1].title + '</p>'
text = text + '<p>#3 :' + items[2].title + '</p>'
except:
pass
return text
#index.html
{% for ranking in rankings %}
<div>
<h4>{{ ranking.title }}</h4>
</div>
<div>
{% autoescape off %}
<div>
{% get_top_3 ranking %}
</div>
{% endautoescape %}
</div>
{% endfor %}
＃Django调试工具栏
1.SELECT "myapp_ranking"."id", "myapp_ranking"."title" FROM "myapp_ranking"
2.SELECT "myapp_item"."id", "myapp_item"."title" FROM "myapp_item" WHERE "myapp_item"."id" IN ('1', '2', '5')
Duplicated 2 times.
3.SELECT "myapp_item"."id", "myapp_item"."title" FROM "myapp_item" WHERE "myapp_item"."id" IN ('8', '10', '7')
Duplicated 2 times.
现在我在数据库中有2个排名，所以有两个重复。更多排名，更多重复。如何减少SQL查询？提前谢谢。