I am making some view functions to calculate the rank of one user in a community.
My problem is that i want to display the rank afferent to each user, in its profile, and i don't know how, since i don;t have a request and a render_to_response (cause i guessed they are not needed)
my code:
def calculate_questions_vote(request):
useranswer = Answer.objects.filter (answer_by = request.user)
positive_votes = VoteUpAnswer.objects.filter(answer = useranswer)
negative_votes = VoteDownAnswer.objects.filter(answer = useranswer)
question_vote_rank = sum(positive_votes) - sum(negative_votes.count)
return question_vote_rank
def calculate_replies(request):
the_new = News.objects.filter(created_by = request.user)
reply = Reply.objects.filter(reply_to = the_new)
reply_rank = sum(reply)
return reply_rank
def calculate_votes(request):
the_new = News.objects.filter(created_by = request.user)
vote = Vote.objects.filter(voted = the_new)
vote_rank = sum(vote)
return vote_rank
def personal_rank(request):
personal_rank = question_vote_rank + reply_rank + vote_rank
return personal_rank
and in UserProfiles:
user = request.user
personal_rank = calculate_questions_vote(user) + calculate_replies(user) + personal_rank(user)
but my error is:
Error binding parameter 0 - probably unsupported type.
Is mt approach correct? How should i call the rank function in the profile_view def ?
Thanks!
YOu can call the function in your view like rank = personal_rank(reuest.user) and add rank to your context then.
I wouldnt call this functions "view"-functions, since they are not dealing with a request nor are they returning a HttoResponce; they are more "helper" functions and also don't belong to a model if they are dealing with seperate entities (eg. News & Vote). A descent place for them would be eg. utils.py. You import them from there in your views.py and call them with the user as parameter (if it's the actual user it's request.user).
It makes sense that you can't access request from everywhere, because this forces you to keep more to a mvc-like design, if you need request somewhere you need to pass it on from your original view function!
You should change your last function to:
def personal_rank(user):
personal_rank = calculate_questions_vote(user) + \
calculate_replies(user) + \
calculate_votes(user)
return personl_rank
You could also add this last function to your User or UserProfile model class if you have something like that and then call eg. my_user.personal_rank() or my_user.get_profile().personal_rank().
lazerscience gave good explanation for your guestion. I just want to point some possible performance issues.
Please note that calling this method for each User yields with 7 queries. If your case will be showing rank for all users it might take a lot of time. I suggest make some caching (like in StackOverflow). There are many options here, for example you can assign special rank field to a User model (or UserProfile if User is auth.User) in which you could store precalaculated rank (calculated just after some operation, like News saving or in some scheduled intervals).
Related
Two models Users (built-in) and Posts:
class Post(models.Model):
post_date = models.DateTimeField(default=timezone.now)
user = models.ForeignKey(User, on_delete=models.CASCADE, null=True, related_name='user_post')
post = models.CharField(max_length=100)
I want to have an API endpoint that returns the percentage of users that have posted. Basically I want SUM(unique users who have posted) / total_users
I have been trying to play around with annotate and aggregate, but I am getting the sum of posts for each users, or the sum of users per post (which is one...). How can I get the sum of posts returned with unique users, divide that by user.count and return?
I feel like I am missing something silly but my brain has gone to mush staring at this.
class PostParticipationAPIView(generics.ListAPIView):
queryset = Post.objects.all()
serializer_class = PostSerializer
def get_queryset(self):
start_date = self.request.query_params.get('start_date')
end_date = self.request.query_params.get('end_date')
# How can I take something like this, divide it by User.objects.all().count() * 100, and assign it to something to return as the queryset?
queryset = Post.objects.filter(post_date__gte=start_date, post_date__lte=end_date).distinct('user').count()
return queryset
My goal is to end up with the endpoint like:
{
total_participation: 97.3
}
Thanks for any guidance.
BCBB
EDIT
OK, I am still struggling a bit. I tried to create a serializer that just had a decimal field for participation_percentage like:
percentage_participation = serializers.DecimalField(max_digits=5, decimal_places=2, max_value=100, min_value=0)
Then I calculate in the view, but I get an error:
Got AttributeError when attempting to get a value for field percentage_participation on serializer ParticipationSerializer.
The serializer field might be named incorrectly and not match any attribute or key on the str instance.
Original exception text was: 'str' object has no attribute 'percentage_participation'.
Error was the same if I made it a CharField (in case there was some string coercion?).
So then I tried to move it to a Serializer Method and put all the calculation logic in there. This calculated fine, but if I had to provide a query_set in the view. If provided a model object, it just returned the percentage as many times as the query (say Posts.objects.all() had a total of 100 posts, it returned the percentage 100 times).
So then I tried to override the get_queryset in the view, but I HAVE to return something. If I just return { "meh", "hello" } then I return the percentage from the SerializerMethodField one time and the end result is exactly what I want.
I just have no idea as to WHY or how to do this correctly.
Thanks for your help.
EDIT #2
OK so I realized why I was only getting one, it was iterating over the string I returned, which was one character. When I returned "meh" it gave me three of the percentage, iterating over each character in the string...
I am not understanding from playing around, reading the docs, or using GoogleFu how to do this properly. I just want to be able to perform some kind of summary logic on records from the DB - how can I do this properly?!?!
Thank you for all your time.
BCBB
something like this should work
# get total user count
total_users = User.objects.count()
# get unique set of users with post
total_users_who_posted = Post.objects.filter(...).distinct("user").count()
# calculate_percentage
percentage = {
"total_participation": (total_users_who_posted*100)/ total_users
}
# take caution of divion by zero
I don't think it is possible to use djangos orm to do this completely but you can use the orm to get the user counts (with posts and total):
from django.db.models import BooleanField, Case, Count, When, Value
counts = (User
.objects
.annotate(posted=Case(When(user_post__isnull=False,
then=Value(True)),
default=Value(False),
output_field=BooleanField()))
.values('posted')
.aggregate(posted_users=Count('pk', filter=Q(posted=True)),
total_users=Count('pk', filter=Q(posted__isnull=False)))
# This will result in a dict containing the following:
# counts = {'posted_users': ...,
# 'total_users': ....}
Would like to be able to access data in a post request directly as well as processing it in the normal way. First created form:
class TransactionForm(ModelForm):
class Meta:
model = Transaction
fields = ['dish', 'customer', 'grams', 'amount_payable']
('customer' is the pk of another model, Customer.)
Then process form:
#csrf_exempt
def create_transaction(request):
print(request.POST)
user_input = TransactionForm(request.POST)
print (user_input)
if user_input.is_valid():
user_input.save()
#customerobject = Customer.objects.get(pk= PK-TAKEN FROM POST)
#customerobject.account_balance -= (amount_payable TAKEN FROM POST)
#customerobject.save()
return HttpResponse('AOK~')
else:
return HttpResponse(user_input) #'ERROR: transaction not valid~')
Am struggling to correctly formulate the commented lines above. (The rest works fine.)
Would like to be able to extract the value 'customer' from the POST in order to find the customer. Then to extract the value 'amount_payable' from the POST in order to deduct it from the customer's balance.
Eventually stumbled upon the relevant command:
cust = user_input.cleaned_data.get('customer')
customerobject = Customer.objects.get(pk=cust.id)
customerobject.account_balance -= user_input.cleaned_data.get('amount_payable')
customerobject.save()
Low-level languages are easier for sieve-heads like me.
While creating a front end for a Django module I faced the following problem inside Django core:
In order to display a link to the next/previous object from a model query, we can use the extra-instance-methods of a model instance: get_next_by_FIELD() or get_previous_by_FIELD(). Where FIELD is a model field of type DateField or DateTimeField.
Lets explain it with an example
from django.db import models
class Shoe(models.Model):
created = models.DateTimeField(auto_now_add=True, null=False)
size = models.IntegerField()
A view to display a list of shoes, excluding those where size equals 4:
def list_shoes(request):
shoes = Shoe.objects.exclude(size=4)
return render_to_response(request, {
'shoes': shoes
})
And let the following be a view to display one shoe and the corresponding
link to the previous and next shoe.
def show_shoe(request, shoe_id):
shoe = Shoe.objects.get(pk=shoe_id)
prev_shoe = shoe.get_previous_by_created()
next_shoe = shoe.get_next_by_created()
return render_to_response('show_shoe.html', {
'shoe': shoe,
'prev_shoe': prev_shoe,
'next_shoe': next_shoe
})
Now I have the situation that the show_shoe view displays the link to the previous/next regardless of the shoes size. But I actually wanted just shoes whose size is not 4.
Therefore I tried to use the **kwargs argument of the get_(previous|next)_by_created() methods to filter out the unwanted shoes, as stated by the documentation:
Both of these methods will perform their queries using the default manager for the model. If you need to emulate filtering used by a custom manager, or want to perform one-off custom filtering, both methods also accept
optional keyword arguments, which should be in the format described in Field lookups.
Edit: Keep an eye on the word "should", because then also (size_ne=4) should work, but it doesn't.
The actual problem
Filtering using the lookup size__ne ...
def show_shoe(request, shoe_id):
...
prev_shoe = shoe.get_previous_by_created(size__ne=4)
next_shoe = shoe.get_next_by_created(size__ne=4)
...
... didn't work, it throws FieldError: Cannot resolve keyword 'size_ne' into field.
Then I tried to use a negated complex lookup using Q objects:
from django.db.models import Q
def show_shoe(request, shoe_id):
...
prev_shoe = shoe.get_previous_by_created(~Q(size=4))
next_shoe = shoe.get_next_by_created(~Q(size=4))
...
... didn't work either, throws TypeError: _get_next_or_previous_by_FIELD() got multiple values for argument 'field'
Because the get_(previous|next)_by_created methods only accept **kwargs.
The actual solution
Since these instance methods use the _get_next_or_previous_by_FIELD(self, field, is_next, **kwargs) I changed it to accept positional arguments using *args and passed them to the filter, like the **kwargs.
def my_get_next_or_previous_by_FIELD(self, field, is_next, *args, **kwargs):
"""
Workaround to call get_next_or_previous_by_FIELD by using complext lookup queries using
Djangos Q Class. The only difference between this version and original version is that
positional arguments are also passed to the filter function.
"""
if not self.pk:
raise ValueError("get_next/get_previous cannot be used on unsaved objects.")
op = 'gt' if is_next else 'lt'
order = '' if is_next else '-'
param = force_text(getattr(self, field.attname))
q = Q(**{'%s__%s' % (field.name, op): param})
q = q | Q(**{field.name: param, 'pk__%s' % op: self.pk})
qs = self.__class__._default_manager.using(self._state.db).filter(*args, **kwargs).filter(q).order_by('%s%s' % (order, field.name), '%spk' % order)
try:
return qs[0]
except IndexError:
raise self.DoesNotExist("%s matching query does not exist." % self.__class__._meta.object_name)
And calling it like:
...
prev_shoe = shoe.my_get_next_or_previous_by_FIELD(Shoe._meta.get_field('created'), False, ~Q(state=4))
next_shoe = shoe.my_get_next_or_previous_by_FIELD(Shoe._meta.get_field('created'), True, ~Q(state=4))
...
finally did it.
Now the question to you
Is there an easier way to handle this? Should shoe.get_previous_by_created(size__ne=4) work as expected or should I report this issue to the Django guys, in the hope they'll accept my _get_next_or_previous_by_FIELD() fix?
Environment: Django 1.7, haven't tested it on 1.9 yet, but the code for _get_next_or_previous_by_FIELD() stayed the same.
Edit: It is true that complex lookups using Q object is not part of "field lookups", it's more part of the filter() and exclude() functions instead. And I am probably wrong when I suppose that get_next_by_FIELD should accept Q objects too. But since the changes involved are minimal and the advantage to use Q object is high, I think these changes should get upstream.
tags: django, complex-lookup, query, get_next_by_FIELD, get_previous_by_FIELD
(listing tags here, because I don't have enough reputations.)
You can create custom lookup ne and use it:
.get_next_by_created(size__ne=4)
I suspect the method you've tried first only takes lookup arg for the field you're basing the get_next on. Meaning you won't be able to access the size field from the get_next_by_created() method, for example.
Edit : your method is by far more efficient, but to answer your question on the Django issue, I think everything is working the way it is supposed to. You could offer an additional method such as yours but the existing get_next_by_FIELD is working as described in the docs.
You've managed to work around this with a working method, which is OK I guess, but if you wanted to reduce the overhead, you could try a simple loop :
def get_next_by_field_filtered(obj, field=None, **kwargs):
next_obj = getattr(obj, 'get_next_by_{}'.format(field))()
for key in kwargs:
if not getattr(next_obj, str(key)) == kwargs[str(key)]:
return get_next_by_field_filtered(next_obj, field=field, **kwargs)
return next_obj
This isn't very efficient but it's one way to do what you want.
Hope this helps !
Regards,
I'm trying to populate a list based on partiular members, but it doesn't seem to be going to plan.
user = request.user
members = []
userprofile = user.get_profile()
if user.is_superuser or user.is_staff:
if userprofile.countries.count() == 0:
members = Member.objects.all()
elif userprofile.countries.count() >0:
for c in userprofile.countries.all():
m1 = Member.objects.filter(location__country = c)
members.append(m1)
else:
pass
self.fields['members'].choices = [(member.id, member.display_name()) for member in members]
Here, we see self.fields (it's a multi-select box) has member.id. I've tried both this and member.pk, but it doesn't seem to be working => Django informs me member has no attributes called id or pk
If a user is a superuser and has a countries count of 0, then It works fine; So i know its to do with the append function underneath the queryset call.
Could anyone offer any hints as to why id/pk is unavailable/lost after adding the results to a list? In addition, does anyone know of a workaround?
I think your problem is that Member.objects.filter(location__country = c) is going to return a QuerySet object... which is essentially a hook to execute a query (lazily) once it is evaluated. if you change that to list(Member.objects.filter(location__country = c)) it will be evaluated immediately and give you back a list of Member model instances instead of a QuerySet object.
There are a couple problems with your code. First, Member.objects.filter(location__country=c) returns a queryset. The queryset is not evaluated by being appended to members (see https://docs.djangoproject.com/en/1.3/ref/models/querysets/#when-querysets-are-evaluated). Second, even if you evaluate the queryset as Matthew suggests, members will be a list of lists, instead of a flat list as your code expects. Try this code instead:
if user.is_superuser or user.is_staff:
if not userprofile.countries.count():
members = Member.objects.all()
else:
members = Member.objects.filter(location__country__in=userprofile.countries.all())
I am trying to access data.get_age_display in my email template. I can't seem to get the display of this. I am not sure what I am doing wrong, I've using get_FIELD_display numerous times before but passed as context to a normal template. Is there something different with forms?
class RequestForm(forms.Form):
ADULT = 1
SENIOR = 2
STUDENT = 3
AGE_GROUP = (
(ADULT, 'Adult'),
(SENIOR, 'Senior'),
(STUDENT, 'Student'),
)
name = forms.CharField(max_length=255)
phone = forms.CharField(max_length=15)
age = forms.ChoiceField(choices=AGE_GROUP)
details = forms.CharField(widget=forms.Textarea())
def save(self):
order = Order(
name = self.cleaned_data['name'],
phone = self.cleaned_data['phone'],
age = self.cleaned_data['age'],
details = self.cleaned_data['details'],
)
order.save()
template = loader.get_template('request_email.txt')
# send over the order object in an email extracted so they can handle the ticket order
context = Context({
'data': order,
})
#import pdb; pdb.set_trace()
email_subject = 'Request Tickets'
mail_managers(email_subject, template.render(context))
in my request_email.txt all I am doing is {{ data.get_age_display }} any ideas?
Jeff
You haven't shown the code for the Order model that you're creating. Are you sure that the age field on the model has choices set?
Any reason you're not using a ModelForm? You're creating an Order object within the form's save() method, but not returning it. A modelform would do that for you, as well as removing the need to redeclare the fields for the form.
I know this is coming WAAAAAY later than the question being posted but here's my answer for completeness and anyone else who might benefit from it :-)
I'm going to assume that in AGE_GROUP, ADULT, SENIOR and STUDENT are integers. Your form cleaning will NOT automatically clean the string contained in the POST and return an integer. So in this code:
context = Context({
'data': order,
})
you would think order.age is referring to an integer but that is, in fact, incorrect. It's burned me a few times before because this will correctly save the integer to the physical table, but the order instance still has the string representation of the age field.
You could do one of two things:
1. Clean this in the field:
clean_age(self):
return int(self.cleaned_data['age'])
or create a new field type:
def MyChoiceField(forms.ChoiceField):
def clean(self, value):
if not value:
if self.required:
raise forms.ValidationError(self.error_messages['required'])
return None
else:
return None
return int(value)
link that to the form field:
age = MyChoiceField(choices=AGE_GROUP)
and then you'll be able to apply this logic to any other such choice field in future. Personally, I find the latter approach the best one and I stick all my custom field types into a form_utils file so that I can use them everywhere. Another gotcha is that forms.charField doesn't automatically strip the entered text and you can use this approach to fix that too.