I've been searching Google, but couldn't find a simple answer to this problem:
I have a django models that stores students information and three other models like this:
class Level(models.Model):
name = models.CharField(max_length=50)
class Pricing(models.Model):
level = models.ForeignKey(Level, on_delete=models.PROTECT)
price = models.PositiveSmallIntegerField(default=0)
class Enrollment(models.Model):
student = models.ForeignKey(Student, on_delete=models.PROTECT)
level = models.ForeignKey(Level, on_delete=models.CASCADE)
date_enrolled = models.DateField()
price = models.PositiveSmallIntegerField(default=0)
I want the Enrollment.price field to be populated dynamically depending on Enrollment.level field value. In javascript, it amounts to setting an event listener to Enrollement.level, but I can't find the equivalent in django.
hi you can modify your save method to fill automatically field price from Level model
Enrollment.level
class Enrollment(models.Model):
student = models.ForeignKey(Student, on_delete=models.PROTECT)
level = models.ForeignKey(Level, on_delete=models.CASCADE)
date_enrolled = models.DateField()
price = models.PositiveSmallIntegerField()
def save(self,*args,**kwargs):
self.price = Pricing.objects.get(level=self.level).price
super().save(*args,*kwargs)
but I recommend to rewrite your model like above example because its simple and you can access to price of every level directly
like Enrollment.level.price
class Level(models.Model):
level = models.CharField(max_length=50,unique=True)
price = models.PositiveSmallIntegerField(default=0)
class Enrollment(models.Model):
student = models.ForeignKey(Student, on_delete=models.PROTECT)
level = models.ForeignKey(Level, on_delete=models.CASCADE)
date_enrolled = models.DateField()
I hope it helped you
Related
I am trying to adapt the Viewflow Dynamicsplit example
The objective is to split approvals of an Order based on OrderLines and to assign them to the appropriate approver. It seems that this should be possible as there seems to be a possibility described in this answer - Assign user to tasks automatically (Viewflow, Django)
The issue is that whenever I try to grab the current order pk in the DynamicSplitActivation - the queryset comes back empty. Not sure where I am going wrong. The queryset works fine if I set the pk manually, but as soon as I try to use a dynamic variable it stops working.
I have listed the flow and models etc. at the end of the post, however, I am guessing the issue is quite basic. Any help would be appreciated!
nodes.py
...
class DynamicSplitActivation(AbstractGateActivation):
def calculate_next(self):
self._order = self.flow_task._order_callback(self.process)
order_id = self._order.pk
# order_id = 28
order_lines = models.OrderLine.objects.filter(order_id=order_id)
project_lines = project_models.ProjectLine.objects.filter(orderline__in=order_lines)
users = User.objects.filter(projectline__in=project_lines).distinct()
self._approvers = users
...
class DynamicSplit(...):
...
def __init__(self, callback):
super(DynamicSplit, self).__init__()
self._order_callback = callback
self._ifnone_next_node = None
...
flows.py
...
approval_split = (
nodes.DynamicSplit(lambda act: act.order)
.IfNone(this.end)
.Next(this.split_approval_budget)
)
models.py
...
class ProjectLine(models.Model):
project = models.ForeignKey(Project, on_delete=models.CASCADE)
description = models.CharField(max_length=50)
budget_holder = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True)
class Order(models.Model):
description = models.CharField(max_length=30)
class OrderLine(models.Model):
order = models.ForeignKey(Order, on_delete=models.CASCADE)
project_line = models.ForeignKey(project_models.ProjectLine, on_delete=models.SET_NULL, null=True, blank=False)
product = models.ForeignKey(catalogue_models.Product, on_delete=models.CASCADE)
quantity = models.PositiveIntegerField()
budgetholder_approved = models.BooleanField(null=True)
class OrderProccess(Process):
order = models.ForeignKey(Order, blank=True, null=True, on_delete=models.CASCADE)
...
I am trying to create an E-Commerce Website and I am at the Final Step i.e. Placing the Order. So, I am trying to add all the Cart Items into my Shipment model. But I am getting this error.
'QuerySet' object has no attribute 'product'
Here are my models
class Product(models.Model):
productId = models.AutoField(primary_key=True)
productName = models.CharField(max_length=200)
productDescription = models.CharField(max_length=500)
productRealPrice = models.IntegerField()
productDiscountedPrice = models.IntegerField()
productImage = models.ImageField()
productInformation = RichTextField()
productTotalQty = models.IntegerField()
alias = models.CharField(max_length=200)
url = models.CharField(max_length=200, blank=True, null=True)
class Customer(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
name = models.CharField(max_length=100, null=True, blank=True)
email = models.EmailField(max_length=100)
profileImage = models.ImageField(blank=True, null=True, default='profile.png')
phoneNumber = models.CharField(max_length=10, blank=True, null=True)
address = models.CharField(max_length=500, blank=True, null=True)
class Order(models.Model):
customer = models.ForeignKey(Customer, on_delete=models.SET_NULL, blank=True, null=True)
dateOrdered = models.DateTimeField(auto_now_add=True)
orderCompleted = models.BooleanField(default=False)
transactionId = models.AutoField(primary_key=True)
class Cart(models.Model):
product = models.ForeignKey(Product, on_delete=models.SET_NULL, blank=True, null=True)
order = models.ForeignKey(Order, on_delete=models.SET_NULL, blank=True, null=True)
quantity = models.IntegerField(default=0, blank=True, null=True)
dateAdded = models.DateTimeField(auto_now_add=True)
class Shipment(models.Model):
customer = models.ForeignKey(Customer, on_delete=models.SET_NULL, blank=True, null=True)
orderId = models.CharField(max_length=100)
products = models.ManyToManyField(Product)
orderDate = models.CharField(max_length=100)
address = models.CharField(max_length=200)
phoneNumber = models.CharField(max_length=13)
I just removed additional functions i.e. __str__ and others.
Here is the views.py
def orderSuccessful(request):
number = Customer.objects.filter(user=request.user).values('phoneNumber')
fullAddress = Customer.objects.filter(user=request.user).values('address')
timeIn = time.time() * 1000 # convert current time in milliSecond
if request.method == 'POST':
order = Shipment.objects.create(customer=request.user.customer, orderId=timeIn,
orderDate=datetime.datetime.now(), address=fullAddress,
phoneNumber=number)
user = Customer.objects.get(user=request.user)
preOrder = Order.objects.filter(customer=user)
orders = Order.objects.get(customer=request.user.customer, orderCompleted=False)
items = orders.cart_set.all() # Here is all the items of cart
for product in items:
product = Product.objects.filter(productId=items.product.productId) # error is on this line
order.products.add(product)
Cart.objects.filter(order=preOrder).delete()
preOrder.delete()
order.save()
else:
return HttpResponse("Problem in Placing the Order")
context = {
'shipment': Shipment.objects.get(customer=request.user.customer)
}
return render(request, "Amazon/order_success.html", context)
How to resolve this error and all the cart items to field products in Shipment model?
Your model is not really consistent at all. Your Cart object is an m:n (or m2m - ManyToMany) relationship between Product and Order. Usually, you would have a 1:n between Cart and Product (a cart contains one or more products). One Cart might be one Order (unless you would allow more than one carts per order). And a shipment is usually a 1:1 for an order. I do not see any of this relationships in your model.
Draw your model down and illustrate the relations between them first - asking yourself, if it should be a 1:1, 1:n or m:n? The latter can be realized with a "through" model which is necessary if you need attributes like quantities.
In this excample, we have one or more customers placing an order filling a cart with several products in different quantities. The order will also need a shipment fee.
By the way: bear in mind that "filter()" returns a list. If you are filtering on user, which is a one to one to a unique User instance, you would better use "get()" as it returns a single instance.
Putting in into a try - except or using get_object_or_404() makes it more stable.
product = Product.objects.filter(productId=items.product.productId)
should be something like:
product = product.product
not to say, it becomes obsolete.
It looks like you make a cart for a product by multiple instances of Cart, the problem is you try to access the wrong variable, also you don't need to filter again when you already have the instance, make the following changes:
carts = orders.cart_set.all() # Renamed items to carts for clarity
for cart in carts:
product = cart.product
order.products.add(product) # The name order is very misleading makes one think it is an instance of Order, actually it is an instance of Shipment
As mentioned above in my comment your variable names are somewhat misleading, please give names that make sense to any variable.
Each time i want to add an invoice, i want to have a unique invoice_id which is an increment number (+1), but the problem is that i have a multiple users app, so i get the error that this invoice_id already exist. how can i customize the ids so each user can have its ids following the latest of same user.
class Company(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
name = models.CharField(max_length=64)
class Invoice(models.Model):
company = models.ForeignKey('Company', on_delete=models.CASCADE)
invoice_id = models.CharField(max_length=20, unique=True)
name = models.CharField(max_length=256)
add an last_invoice field in your company record. Then let it do the work for you by adding a function that generates new invoice:
class Company(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
name = models.CharField(max_length=64)
last_invoice = models.CharField(max_length=20)
def get_invoice(self):
l_newNum = self.last_invoice + '1' #your number here
self.last_invoice = l_newNum
self.save()
return l_newNum
class Invoice(models.Model):
company = models.ForeignKey('Company', on_delete=models.CASCADE)
#you no longer need unique as it will create a mess between companies
invoice_id = models.CharField(max_length=20)
name = models.CharField(max_length=256)
def save(self):
self.invoice_id = self.company.get_invoice()
super(Invoice,self).save()
You need to fill in the details here and there, but this should work for you. IDeally I would suggest that the get_invoice is actually used to automatically create Invoice entry for the company, but this would depend on the concrete case you are building.
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'm new in Django and DRF, have questions with serialization.
I have models:
class Commodity(models.Model):
shop = models.ForeignKey(Company, on_delete=models.PROTECT)
price = models.DecimalField(max_digits=10, decimal_places=2)
active = models.BooleanField(default=False)
class Clother(models.Model):
commodity = models.ForeignKey(Commodity, related_name='commodity', on_delete=models.CASCADE)
color = models.ManyToManyField(Color, related_name='color')
material = models.ManyToManyField(Material, related_name='material')
gender = models.CharField(max_length=2, choices=GENDER_CHOICES, default=UNISEX)
class Outwear(models.Model):
clother = models.ForeignKey(Clother, on_delete=models.CASCADE)
name = models.CharField(max_length=30, blank=True)
outwear_type = models.ForeignKey(OutwearType, on_delete=models.CASCADE)
size = models.ManyToManyField(ClotherSize)
So I suppose to make a Serializer like that:
class OutwearSerializer(serializers.ModelSerializer):
commodity = CommoditySerializer(many=False, read_only=False)
clother = ClotherSerializer(many=False, read_only=False)
class Meta:
model = Outwear
fields = ('commodity', 'clother', 'name', 'outwear_type', 'size')
As I understand that read_only fields let me add or edit Outwear object further, but I supposed to have 2 types of permition:
All users can see only active Commodity objects.
Only Companies can create and edit their own objects.
Do I need to make 2 Serializer Models for read_only=True/False?
What is the best practice and where can I find good examples of something familiar?
I call User - unauthorized User. Company is authorized User.
Thanks!
For your first question:
class CommoditySerializer(ModelSerializer):
class Meta:
model = Commodity
fields = (shop, price)
Class CommodityActiveAPIView(generics.ListAPIView):
serializer_class = serializers.CommoditySerializer
queryset = Commodity.objects.filter(active=True)
second question is ambiguous. first define user role please