Django - How to query and display multiple relationship struture - django-models

Question

I'm building a RSS feed reader where users can add own feeds and categories. I want to store content all of the the feeds in db and run a script that would fetch that content for all of the feed_url present in db periodically (I had working project where each feed is fetched live and it wasn't good idea)
Now after several attempts I got into the following model structure.
class Category(models.Model):
name = models.CharField(unique=False, max_length=64)
user = models.ForeignKey(User)
def __unicode__(self):
return self.name
class Meta:
ordering = ('name',)
class Feed(models.Model):
feed_url = models.URLField(unique=True)
def __unicode__(self):
return self.feed_url
class UserFeed(models.Model):
feed = models.ForeignKey(Feed)
title = models.CharField(max_length=256)
category = models.ForeignKey(Category)
user = models.ForeignKey(User)
def __unicode__(self):
return self.title
class Post(models.Model):
feed = models.ForeignKey(Feed, related_name='feed_posts')
## starting from here, my cronjob / script populates the data (using feedparser lib)
title = models.CharField(max_length=256)
content = models.TextField()
link = models.URLField(max_length=512)
dt_published = models.DateTimeField()
dt_cached = models.DateTimeField(auto_now_add=True)
def __unicode__(self):
return '%s (%s)' % (self.feed, self.title)
class Meta:
ordering = ('-dt_published',)
What I'm looking for now is ability for pull into a view and later into templates, the following entities:
->Category -> Feed -> Posts
In my previous version where Feed and UserFeed fields were stored in one table/model, I had such view:
def category(request, category_id):
user = request.user
page_title = "Category: "
category = get_object_or_404(Category.objects.filter(id=category_id, user=user)).feed_set.all()
category_name = Category.objects.get(id=category_id)
context = {
'page_title': page_title,
'category': category,
'category_name': category_name,
}
return expand_context_and_render(request, context, 'reader/category.html')
and this is my template:
{% for feed in category %}
<p>{{ feed.title }}</p>
{% for post in feed.post_set.all|slice:"6" %}
<p>{{ post.title }}</p>
<p>{{ post.content }}</p>
<p>{{ post.dt_published|timesince }} ago.</p>
{% endfor %}
{% endfor %}
And it was working as intended.
Now, since I don't want to have multiple copies of feed_url in my database, I think the new models are OK, but I simply can't figure out how to query and display this new structure which has upstream and downstream relationships. I was looking at select_related but didn't get it to work. Could you please help ?

Answer 1

I eventually found the solution myself. It's bit hacky :( but does the job.
def category(request, user_category_id):
user = request.user
page_title = "Category: "
user_category = get_object_or_404(Category.objects.filter(id=user_category_id, user=user))
user_feeds = UserFeed.objects.filter(category=user_category, user=user)
context = {
'page_title': page_title,
'user_category': user_category,
'user_feeds': user_feeds,
}
return expand_context_and_render(request, context, 'reader/category.html')
and template:
{% for user_feed in user_feeds %}
<p><strong>{{ user_feed }}</strong></p>
{% for post in user_feed.feed.post_set.all|slice:"6" %}
<div class="col-md-4">
<p>{{ post.title|truncatechars:"45" }}</p>
<p>{{ post.content|striptags|safe|truncatechars:"85" }}</p>
<p class="feed_date">{{ post.dt_published|timesince }} ago.</p>
<hr />
</div>
{% endfor %}
{% endfor %}