Tuesday, May 3, 2016

Re: Querying a model with a ForeignKey

Does

pModel = PostModel.objects.filter(topicid_id=pk).order_by('-pub_date')[0]

work for you?

Also, I believe it would be more conventional if you named your
topicid field simply topic, your post field as body, and your topic
field as name.

Luck.

Aaron

On 5/3/16, ofeyofey <shanegibney@gmail.com> wrote:
> I have two tables in a sqlite3 DB, PostModel and TopicModel. The PostModel
> has fields id, post, author, pub_date and topicid. This last fields topicid
>
> has a foreignkey to the other table Postmodel. PostModel has the fields id,
>
> topic.
> There is a one-to-many relation from the TopicModel to the PostModel. So a
> Topic can have many posts but a post can only have one topic.
> I would like to create query the PostModel to get the latest post for each
> topicid.
> So something like, SELECT PostModel.topicid WHERE date_pub is the latest.
> But i would like to use the Django Query API not SQL.
> My models look like this,
>
> class TopicModel(models.Model):
> topic = models.CharField(max_length=300)
> extra = models.CharField(max_length=100)
>
> def __str__(self): # __unicode__ on Python 2
> return self.topic
>
> class PostModel(models.Model):
> post = HTMLField(blank=True)
> pub_date = models.DateTimeField('date published')
> author = models.CharField(max_length=30)
> topicid = models.ForeignKey(TopicModel, related_name = 'topicThing')
>
> def __str__(self): # __unicode__ on Python 2
> return self.post
>
> Here is the view
>
> def thread(request, id):
> if request.method == "POST":
> print 'we are inside POST'
> pk = id
> tform = get_object_or_404(TopicModel, pk=id)
> Pform = PostForm(request.POST)
> if Pform.is_valid():
> # tform = Tform.save(commit=False)
> pform = Pform.save(commit=False)
> pform.topicid = tform
> # pform.topicid = pk
> pform.author = request.user
> pform.pub_date = timezone.now()
> pform.save()
> # return redirect('post_detail', pk=post.pk)
> return redirect('thread', id)
> else:
> pk=id
> pModel = reversed(PostModel.objects.all().filter(topicid_id=pk))
> postform = PostForm()
> return render(request, 'thread.html', {'pModel': pModel, 'postform' :
> postform})
>
> Thanks
>
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