模板中的Django过滤器查询集

Question

I'm still studying in school and still new in Python language & Django framework and I'm trying doing projects to learn the best practice for it.

Right now I'm building a project like following :

• Topics Model => which is user can write a new topic
• Replies Model => which is user can write a new reply for a specific topic
• Likes Model => which is user can vote up or down for a topic or reply

it's a little bit close from stackoverflow site .

Models.py

class Topic(models.Model):
user = models.ForeignKey(CustomUser, on_delete=models.CASCADE)
title = models.CharField(max_length=400)
like = models.IntegerField(default=0)
dislike = models.IntegerField(default=0)
image = models.FileField(blank=True, null=True)
created_date = models.DateTimeField(auto_now=True)

def __str__(self):
    return self.title[0:51]



class Reply(models.Model):
user = models.ForeignKey(CustomUser, on_delete=models.CASCADE)
topic = models.ForeignKey(Topic, on_delete=models.CASCADE)
reply = models.TextField()
created_date = models.DateTimeField(auto_now=True)

def likes(self):
    return Likes.objects.filter(reply=self, reply_flag=1).count()
    likes.short_description = 'likes'

def dislikes(self):
    return Likes.objects.filter(reply=self, reply_flag=-1).count()
    dislikes.short_description = 'dislikes'

def __str__(self):
    return self.reply



class Likes(models.Model):
user = models.ForeignKey(CustomUser, on_delete=models.CASCADE)
reply = models.ForeignKey(Reply, on_delete=models.CASCADE)
reply_flag = models.CharField(max_length=5, choices=(
('0', 'No'), ('1', 'Positive'), ('-1', 'Negative')))  # 1 = vote up , -1 vote down

Views.py

# get all topics 
def Topics(request):
topics = models.Topic.objects.all()
return render(request, 'Topics.html', {'topics': topics})



# get detail of specific topic
def TopicDetails(request, topic_id):
topic = get_object_or_404(models.Topic, pk=topic_id)
return render(request, 'Topic_Details.html', {'topic': topic, 'Likse': models.Likes.objects.all})

Templates:

topics.html :

 {% for topic in topics %}

   {% if topic.image}
      <img src="{{topic.image.url}}"
   {% endif %}
   title : {{ topic.title }}
   by : {{ topic.user }}
   total agree : {{ topic.like }}
   total not agree : {{ topic.dislike }}

{% endfor %}

topic.html :

 topic title : {{ topic.title }}

 {% for reply in topic.reply_set.all %}

   reply : {{ topic.reply }}
   by : {{ reply.user }}
   total agree : {% for like in reply.lieks_set.all %} {% if like.reply == reply and like.reply_flag == '1' %} <!-- should be total of vote up --> {% endif %} {%endfor %}
   total not agree : {% for like in reply.lieks_set.all %} {% if like.reply == reply and like.reply_flag == '-1' %} <!-- should be total of vote down --> {% endif %} {%endfor %}

{% endfor %}

I faced an issue with filter likes based on reply, user and reply flag (vote up, vote down) in topic.html, I have two questions :

• As my knowledge and as I read after search I couldn't filter data in template, So how could I show the filtered data in template based on reply, user and reply flag (vote up, vote down) ?
• Is structure of app is correct ?

Answer 1

First of all, you should definitely make use of generic views (like DetailView or TemplateView ). You have couple of options on how to include proper information, decide which is simpler for you:

1. Override a get_context of a generic view (and include aggregates in a template variable)
2. Override get_queryset of a view (inluding aggregates in a query)
3. Create a custom model manager and include appropriate aggregates in a queryset.

See aggregate and annotate for more information on how to count or sum dependent models.