Re: Querying a model with a ForeignKey

[ofeyofey]

This also grabs the frequency or number of views per post.

On Tuesday, 3 May 2016 18:43:53 UTC+1, ofeyofey 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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Re: Querying a model with a ForeignKey

[ofeyofey]

Hi,
Just in case it is useful to anyone, here is the solution,

>
> pModel = PostModel.objects.raw('SELECT *, max(pub_date), count(topicid_id) 
> AS freq FROM crudapp_postmodel GROUP BY topicid_id ORDER BY pub_date DESC 
> LIMIT 0,20')


Thanks

On Tuesday, 3 May 2016 18:43:53 UTC+1, ofeyofey 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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Re: Querying a model with a ForeignKey

[ofeyofey]

No problem. I will post if i figure it out.
Thanks very much for your help

On Tuesday, 3 May 2016 18:43:53 UTC+1, ofeyofey 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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Re: Querying a model with a ForeignKey

[Aaron Cannon]

I fear doing this efficiently is beyond my limited abilities.  Will
look forward to other answers you might get.

Good luck.

Aaron

On 5/3/16, ofeyofey  wrote:
> Aaron thanks for looking at this.
> I understand what you did now, and that is great.
> But I actually realised that the views I showed are not the correct ones
> and the view I want to do this in called 'init' actually has no id.
> So How might I get one instance of each topic where if there is more than
> one instance I get the latest one only?
>
> Here is the view i should have posted.
>
> def init(request):
> # tModel = reversed(TopicModel.objects.all())
> # pModel = reversed(PostModel.objects.all())
> pModel =
> reversed(PostModel.objects.filter(topicid_id=pk).order_by('-pub_date')[0])
> # context = {'tModel': tModel, 'pModel': pModel}
> context = {'pModel': pModel}
> return render(request, 'forum.html', context)
>
> Thanks again,
>
>
> On Tuesday, 3 May 2016 18:43:53 UTC+1, ofeyofey 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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> For more options, visit https://groups.google.com/d/optout.
>

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Re: Querying a model with a ForeignKey

[ofeyofey]

Aaron thanks for looking at this.
I understand what you did now, and that is great.
But I actually realised that the views I showed are not the correct ones 
and the view I want to do this in called 'init' actually has no id.
So How might I get one instance of each topic where if there is more than 
one instance I get the latest one only?

Here is the view i should have posted.

def init(request):
# tModel = reversed(TopicModel.objects.all())
# pModel = reversed(PostModel.objects.all())
pModel = 
reversed(PostModel.objects.filter(topicid_id=pk).order_by('-pub_date')[0])
# context = {'tModel': tModel, 'pModel': pModel}
context = {'pModel': pModel}
return render(request, 'forum.html', context)

Thanks again,


On Tuesday, 3 May 2016 18:43:53 UTC+1, ofeyofey 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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Re: Querying a model with a ForeignKey

[Aaron Cannon]

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  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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>

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