I am trying to run query that sum of the same record that on the database. It is more clear to use codes instead of words.
class Track(models.Model):
title = models.CharField()
isrc = models.CharField()
...
class Playlog(models.Model):
track = models.ForeignKey(Track, on_delete=models.CASCADE)
....
On database there is multiple record which has same isrc value. To get real playlog data I needed to get total playlog count which has same isrc of all Track. I tried following query but it shows me a duplicated values of Track. if there is same isrc I wanted to get sum of all playlog of same isrc record.
Playlog.objects.values("track__isrc").annotate(Count("track__playlog", filter=Q(track__playlog__duration__gte=10))
You should add a .order_by('track__isrc') to force it to "fold". You should also count on the model, not on a related model:
Playlog.objects.values('track__isrc').annotate(
Count('pk', filter=Q(duration__gte=10)
).orer_by('track__isrc')
That being said, if the same value of isrc means it is the same product, etc. It is better to make a model and a ForeignKey to that product, for example:
class Product(models.Model):
isrc = mode.sCharField(max_length=128, unique=True)
# …
class Track(models.Model):
title = models.CharField(max_length=128)
isrc = models.ForeignKey(Product, on_delete=models.CASCADE)
# …
class Playlog(models.Model):
track = models.ForeignKey(Track, on_delete=models.CASCADE)
duration = models.IntegerField()
# …
Then you can annotate the Product, for example:
from django.db.models import Count, Q
Product.objects.annotate(
total_play=Count('track__playlog', filter=Q(track__playlog__duration__gte=10))
)
Related
Good afternoon,
I am really struggling with getting a sum using Annotate in DJango.
I am using User object and the following models:
class Depts(models.Model):
dept_name = models.CharField(max_length=55)
dept_description = models.CharField(max_length=255)
isBranch = models.BooleanField(default=False)
def __str__(self):
return "{}".format(self.dept_name)
class UserProfile(models.Model):
user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='profile')
title = models.CharField(max_length=75)
dept = models.ForeignKey(Depts, on_delete=models.CASCADE, related_name="dept", null=True)
class ActivityLog(models.Model):
activity_datetime = models.DateTimeField(default=timezone.now)
user = models.ForeignKey(User, on_delete=models.CASCADE, null=True, related_name='activity_user')
activity_category = models.ForeignKey(ActivityCategory, on_delete=models.CASCADE, null=True, related_name='activity_cat')
activity_description = models.CharField(max_length=100, default="Misc Activity")
class ActivityCategory(models.Model):
activity_name = models.CharField(max_length=40)
activity_description = models.CharField(max_length=150)
pts = models.IntegerField()
def __str__(self):
return '%s' % (self.activity_name)
What I need to do is get a group of departments with aggregating the sum of the pts earned by all the users activitylogs.
So a user is part of department, they do activities, each activity is of a type activity_category and has associated points. How can I query using the ORM to get a sum of points for everyone in each department?
Thank you, I cannot seem to wrap my mind around it.
You annotate the departments with the sum:
from django.db.models import Sum
Depts.objects.annotate(
total_pts=Sum('dept__user__activity_user__activity_category__pts')
)
Note: The related_name=… parameter [Django-doc]
is the name of the relation in reverse, so from the Depts model to the UserProfile
model in this case. Therefore it (often) makes not much sense to name it the
same as the forward relation. You thus might want to consider renaming the dept relation to userprofiles.
After setting the related_name='userprofiles', the query is:
from django.db.models import Sum
Depts.objects.annotate(
total_pts=Sum('userprofiles__user__activity_user__activity_category__pts')
)
I'd like to ask, how I could shrink this to one command? I understand that annotate is proper way to do this,but don't understand how.
Here is my code, which is too slow:
sum = 0
for contact in self.contacts.all():
sum += (contact.orders.aggregate(models.Sum('total'))['total__sum'])
return sum
I'd like to get Sum for each contact, all records in total column of relevant orders.
Code above produces sum, but is sluggishly slow. It is my understand it can be done with annotate,but not sure how to use it.
Here is Contact:
class Contact(models.Model):
company = models.ForeignKey(
Company, related_name="contacts", on_delete=models.PROTECT)
first_name = models.CharField(max_length=80)
last_name = models.CharField(max_length=80, blank=True)
email = models.EmailField()
And here is Orders:
class Order(models.Model):
order_number = models.CharField(max_length=80)
company = models.ForeignKey(Company, related_name="orders")
contact = models.ForeignKey(Contact, related_name="orders")
total = models.DecimalField(max_digits=12, decimal_places=6)
order_date = models.DateTimeField(null=True, blank=True)
Help please
You can annotate your queryset on the Contract model with:
from django.db.models import Sum
Contract.objects.annotate(
total_orders=Sum('orders__total')
)
The Contract objects that arise from this queryset will have an extra attribute .total_orders that contains the sum of the total field of the related Order objects.
This will thus create a query that looks like:
SELECT contract.*, SUM(order.total)
FROM contract
LEFT OUTER JOIN order ON order.contract_id = contract.id
GROUP BY contract.id
I have a class Summary:
class Summary(models.Model):
title = models.CharField(max_length=128)
category = models.ForeignKey(Category)
subcategory = models.ForeignKey(Subcategory)
content = RichTextField(null=True, blank=True)
users_rated_positive = models.ManyToManyField(
User, blank=True, related_name='summaries_rated_positive')
users_rated_negative = models.ManyToManyField(
User, blank=True, related_name='summaries_rated_negative')
author = models.ForeignKey(User, related_name='summaries_authored')
and a class UserProfile:
class UserProfile(models.Model):
user = models.OneToOneField(User, primary_key=True, related_name='profile')
karma = models.IntegerField(default=0)
rank = models.IntegerField(null=True,blank=True)
I want the karma to be calculated as the positive ratings on all the users summaries minus the negative ratings on all the users summaries
I figured I could add a property like this instead of a field:
#property
def karma(self):
summaries_list = self.user.summaries_authored.all()
positive_karma = sum(
[summary.users_rated_positive.count() for summary in summaries_list])
negative_karma = sum(
[summary.users_rated_negative.count() for summary in summaries_list])
return positive_karma - negative_karma
Is this the right way to do this? I feel like I should be using aggregate, or annotate but to be honest I'm new to Django and not entirely sure how they work for complex situations.
from django.db.models import Count
positive_karma = Summary.objects.filter(author=self.user).aggregate(pos_count=Count('users_rated_positive'))['pos_count']
negative_karma = Summary.objects.filter(author=self.user).aggregate(neg_count=Count('users_rated_negative'))['neg_count']
aggregate returns a dict so the actual value must be retrieved by the key
You would use annotate if you wanted to get the count of pos/neg ratings for every user.
I have models like this:
class Person(models.Model):
first_name = models.CharField(max_length=60)
last_name = models.CharField(max_length=60)
class Ticket(models.Model):
assigned_to = models.ForeignKey(Person, null=True, blank=True)
estimate = models.DecimalField(null=True, blank=True, decimal_places=1, max_digits=4)
I want to find the total of all estimates for all tickets that are assigned to a particular person.
I am trying to do:
for i in Person.objects.all():
Ticket.objects.filter(assigned_to=i)
and use Sum() to add estimate() for each model.
But I am getting no data with the first query. I am sure I have datas. What's wrong?
You can do this entirely in the db with an aggregate.
from django.db.models import Sum
people_with_estimates = Person.objects.all().annotate(
estimate_total=Sum('ticket__estimate'))
Now each Person has an estimate_total attribute containing the sum of all their ticket estimates.
Assuming you know the person try this:
estimate_total = Decimal(0)
ticket_list = Ticket.objects.filter(assigned_to = person.id)
for i in range(len(ticket_list)):
estimate_total += ticket_list[i].estimate
Guys,
Is there an easy way to return different fields names from different models by chaining joins?
My model:
Class Item(models.Model):
item_code = models.CharField(max_length=10)
name = models.CharField(max_length=255)
...
Class Stock(models.Model):
item_code = models.ForeignKey( Item )
userid = models.ForeignKey( User )
qty = models.IntegerField()
...
I want to select " Item.Item_code, Item.name, Stock.qty where Stock.userid=2 and Item.item_code = Stock.Item_Code"
How do i do this in Django?
Gath
I want to select " Item.Item_code, Item.name, Stock.qty where Stock.userid=2 and Item.item_code = Stock.Item_Code"
You can pick these specific fields only using one SQL, provided you start from the Stock model. For instance
q = Stock.objects.select_related('userid', 'item_code').filter(
userid__id = 2).values('item_code__item_code', 'item_code__name', 'qty')
This will help if you want to limit the data and then number of queries. If you are not concerned with this then do:
q = Stock.objects.filter(userid__id = 2)
for stock in q:
print stock.item_code.item_code
print stock.item_code.name
print stock.qty
This will return a queryset with only those fields you have chose using values. You can then iterate through it.
PS: Re: your models.
Class Stock(models.Model):
item_code = models.ForeignKey( Item )
userid = models.ForeignKey( User )
qty = models.IntegerField()
...
It is a good idea to use the model name in lower case for FK relationships. For e.g. you ought to write:
Class Stock(models.Model):
item = models.ForeignKey( Item ) # Changed
user = models.ForeignKey( User ) # Changed
qty = models.IntegerField()
...
You can also use this:
Stock.objects.filter(user=2).values('item__item_code', 'item__name')
First of all change fileds names
Read this very carefuly http://docs.djangoproject.com/en/dev/ref/models/querysets/
Class Item(models.Model):
item_code = models.CharField(max_length=10)
name = models.CharField(max_length=255)
...
Class Stock(models.Model):
item = models.ForeignKey( Item )
user = models.ForeignKey( User )
qty = models.IntegerField()
...
#view
stocks = Stock.objects.filter(user=2)
for stock in stocks:
print stock.item.item_code, stock.item.name
#one query version