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How can I fetch data by joining two tables in django?

Looking for help got stuck at a point, I am new to python and django. There ARE two payments corresponding to one order, one COLLECTION and multiple TRANSFER and i need the payment corresponding to an order whose direction is COLLECTION only NOT transfered yet so that i can initiate TRANSFER against that order
models.py
class Orders(models.Model):
id= models.AutoField(primary_key=True)
payment_gateway_code = models.CharField(max_length=20,choices=[('PAYTM','PAYTM')])
is_active = models.BooleanField(default=True)
class Payments(models.Model):
id = models.AutoField(primary_key=True)
orders = models.ForeignKey(Orders, on_delete=models.CASCADE)
direction = models.CharField(max_length=20,choices=[('COLLECTION','COLLECTION'),
('TRANSFER','TRANSFER')])
settlement_status = models.CharField(max_length=50,blank=True, null=True,choices=[('YES','YES'),
('NO','NO')])
is_active = models.BooleanField(default=True)
qualified_orders = Orders.objects.filter(payment_gateway_code='CASHFREE',
Exists(Payments.objects.filter(order=OuterRef('pk'), direction='COLLECTION',
settlement_status='YES')), ~Exists(Payments.objects.filter(order=OuterRef('pk'),
direction='TRANSFER')))
But above query is not working

What is OuterRef('pk')?
First, I'd suggest changing orders to order.
Then, the query you're trying to achieve will be something like this (Assuming order_id contains the ID of the order):
Paymen.objects.filter(order_id=order_id, direction="COLLECTION")

You can use views.py for that as follows
Models.py
class Orders(models.Model):
id= models.AutoField(primary_key=True)
payment_gateway_code = models.CharField(max_length=20,choices=[('PAYTM','PAYTM')])
is_active = models.BooleanField(default=True)
class Payments(models.Model):
id = models.AutoField(primary_key=True)
orders = models.ForeignKey(Orders, on_delete=models.CASCADE)
direction = models.CharField(max_length=20,related_name="direction",choices=[('COLLECTION','COLLECTION'),
('TRANSFER','TRANSFER')])
settlement_status = models.CharField(max_length=50,blank=True, null=True,choices=[('YES','YES'),
('NO','NO')])
is_active = models.BooleanField(default=True)
views.py
from App.models import orders, payments
#in case if you need objects of order this is for that
def orderfunc():
order = Orders.objects.all()
def paymentfunc():
payment = Payment.objects.all()
# from here you can check for what record you want using conditional operator
#if direction == COLLECTION:
#then do what you need

Django form: Update model values based on user input in one field

I am writing a form to let a user enter a purchase from the template. A couple things need to happen:
the purchase goes to populate a row in the replenishment table
some fields of the replenishment table get updated based on what the user has input
here is what my model look like:
class replenishment(models.Model):
Id = models.CharField(max_length=100, primary_key=True, verbose_name= 'references')
Name = models.CharField(max_length=200)
Quantity = models.FloatField(default=0)
NetAmount = models.FloatField(default=0)
SupplierID = models.CharField(max_length=200)
Supplier = models.CharField(max_length=200)
SellPrice = models.FloatField(default=0)
StockOnOrder = models.FloatField(default=0)
StockOnHand = models.FloatField(default=0)
def __str__(self):
return self.reference
and the form:
class ProcurementOperationRecord(forms.Form)
Id = forms.CharField(required=True)
Quantity = forms.FloatField(required=True)
NetAmount = forms.FloatField(required=True)
Supplier = forms.CharField(required=True)
SellPrice = forms.FloatField(required=True)
I have no clue how to let the user input the values in form and automatically add Quantity to StockOnOrder as well as automatically recognize the SupplierID based on Supplier. At this point I don't know where to start really. At least, is it possible to achieve what I try to do?

First, I've changed some things around and added some comments to what and why I did them.
# models/classes in python are singular AND camel cased (99.9%)
class Supplier(models.Model):
...
# models/classes in python are singular AND camel cased (99.9%)
class Replenishment(models.Model):
# attributes are normally lower case and snake cased (99.9%)
# try not to do this, a CharField??, unless you're using a guid? if so use UUIDField()
# https://docs.djangoproject.com/en/3.1/ref/models/fields/#uuidfield
id = models.CharField(db_column='Id', max_length=100, primary_key=True, verbose_name='references')
name = models.CharField(db_column='Name', max_length=200)
quantity = models.FloatField(db_column='Quantity', default=0)
net_amount = models.FloatField(db_column='NetAmount', default=0)
# deleted your field "Supplier" -- with this change you can join to the other table and get what you need without having to duplicate anything
supplier = models.ForeignKey(Supplier, db_column='SupplierID')
sell_price = models.DecimalField(db_column='SellPrice', default=0, max_digits=6, decimal_places=2) # You're asking for trouble if you keep this as FloatField
stock_on_order = models.IntegerField(db_column='StockOnOrder', default=0) # how can you have ordered a .5 for your stock? changed to IntegerField
stock_on_hand = models.IntegerField(db_column='StockOnHand', default=0) # how can you have a .5 of your stock? changed to IntegerField
class Meta:
db_table = 'replenishment' # try not to do this either.. let django come up with the name.. unless you're using an existing database/table?
...
# models/classes in python are singular AND camel cased (99.9%)
# django has a standard that they normally postfix forms with "Form" at the end of the class (no matter if it's a ModelForm or regular Form)
class ProcurementOperationRecordForm(forms.ModelForm)
class Meta:
model = Replenishment
fields = ('id', 'quantity', 'net_amount', 'supplier', 'sell_price')
# I would remove the "id", the client shouldn't care or know about it..
Now to create and update. (This would live inside a view)
# creating?
form = ProcurementOperationRecordForm(data=request.POST)
if form.is_valid():
form.save()
return redirect(..) or render(..)
# updating?
replenishment = Replenishment.objects.get(id='...something')
form = ProcurementOperationRecordForm(data=request.POST, instance=replenishment)
if form.is_valid():
form.save()
return redirect(..) or render(..)

This is just a general idea. You can try something like this.
First get the user input values of quantity and supplier like this from the valid form.
quantity = form.cleaned_data.get('quantity')
supplier = form.cleaned_data.get('supplier')
Then you can update your replenishment model
replenishment.objects.filter(Supplier=supplier).update(StockOnOrder=quantity)

Django Cannot assign "'Pizza'": "Order.Food_Name" must be a "Foods" instance

Hello Guys I am working on a restaurant project which allow user to select food item and book an order but i am getting this error as i try to book an order
"Django Cannot assign "'Pizza'": "Order.Food_Name" must be a "Foods" instance."
I am using drop down menu to select food items i am using django version 2.1.5 . Please Help
views.py
def place_order(request):
name = request.POST["user"]
food_items = request.POST['food_item']
qty = request.POST['qty']
rating = request.POST['ratings']
price = Foods.Food_Price
order = Order(Date=datetime.date, Name_of_Person=name,Food_Name=food_items, Qty=qty, Total=price, Ratings=rating)
order.save()
return render(request, "index.html")
model.py
from django.db import models
class Foods(models.Model):
Food_Number = models.IntegerField(null=False,)
Food_Name = models.CharField(max_length=30, primary_key=True, null=False)
Food_Qty = models.CharField(max_length=10)
Food_Price = models.IntegerField()
def __str__(self):
return f"{self.Food_Number} - {self.Food_Name} {self.Food_Price}"
class Order(models.Model):
Order_id = models.AutoField(null=False, primary_key=True)
Date = models.DateField()
Name_of_Person = models.CharField(null=False, max_length=40)
Food_Name = models.ForeignKey(Foods, on_delete=models.CASCADE)
Qty = models.CharField(max_length=10)
Total = models.IntegerField()
Ratings = models.IntegerField()
def __str__(self):
return f"{self.Order_id} - {self.Name_of_Person} |{self.Food_Name} |{self.Total}"
What can i do solve this error

Problem is in your Order model Food_Name is foreign-key field. So you need to assign model-instance which is Food in this case to this field. But you are assigning food_items = request.POST['food_item'] which is suppose to be food_name string i guess. That is why this error raise. I don't think your model is properly design. Food_Name is not an unique id field in Food model rather in your Order table you would like to have Food not Food_name.

Django choices in Admin when Enum is used

I have a model where I am using Enum for choices:
class Agreement(models.Model):
class Category(enum.Enum):
EULA = 0
PROVIDER = 1
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
category = models.IntegerField(
choices=[(choice.name, choice.value)
for choice in Category])
title = models.CharField(max_length=128)
content = models.TextField()
I register it using simple admin site registration:
admin.site.register(Agreement)
When admin site renders the object it doesn't allow me to save it? Has anyone had a similar issue?

According to the documentation:
The first element in each tuple is the actual value to be set on the model, and the second element is the human-readable name.
name and value should be the other way around, like this:
category = models.IntegerField(
choices=[(choice.value, choice.name)
for choice in Category])
because category is an integer field and name returns a string.

Django order by primary key does not work

I have a model as below:
class Photos(models.Model):
id = models.IntegerField(primary_key=True, default=1)
name = models.CharField(max_length=500)
size = models.IntegerField()
path = models.CharField(max_length=500)
date = models.DateField(default=datetime.now)
def __str__(self):
return self.date.strftime('%Y-%m-%d')
class Meta:
verbose_name_plural = "Photos"
I want to retrieve the last primary key from the database (postgresql) as below:
try:
last_inserted = Photos.objects.order_by('-id')[0]
print(last_inserted)
except IndexError:
print("No data in the database")
but instead of a primary key I always get a date from the date column which is really strange! printing the last_inserted gives me '2018-09-04'.
As a test I change the 'id' column to lang (does not exists in table) gives below error message:
Cannot resolve keyword 'lang' into field. Choices are: date, id, name, path, size
in the above message why date is coming first then id and so on ..!
please help!

print(last_inserted) will show you result of model's __str__ method. To see id you can change model:
class Photos(models.Model):
id = models.IntegerField(primary_key=True, default=1)
name = models.CharField(max_length=500)
size = models.IntegerField()
path = models.CharField(max_length=500)
date = models.DateField(default=datetime.now)
def __str__(self):
return str(self.id)
class Meta:
verbose_name_plural = "Photos"
Or just change query to select only id field using values_list:
last_inserted = Photos.objects.order_by('-id').values_list('id', flat=True)[0]
print(last_inserted)
As for
in the above message why date is coming first then id and so on ..!
I suppose it because of alphabetical order.

You can also try it like this. A bit shorter
Photos.objects.order_by('-id').first().id
There is also a last()