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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)

Trying to know how many rows I have from the different fleets in django

I'm working with a project that has 3 models.
Devices: All the devices involved in the project.
Fleets: Each device is in one fleet.
Data: The data that the devices send.
Now I want to know how much data have come me today.
In my view I have this,
def dataPlots(request):
today = datetime.date(2020, 5, 18)
data = DevData.objects.filter(data_timestamp__date=today)
data = loads(serializers.serialize('json', data))
If I use len() I can now the total value. But how can I know how much data do I have for each fleet?
I have come to create this loop that would tell me for each device, but what I need is the value for each fleet and furthermore I think I am getting complicated.
data_dict = {}
for d in data:
if d['fields']['dev_eui'] in data_dict:
data_dict[d['fields']['dev_eui']] = data_dict[d['fields']['dev_eui']] + 1
else:
data_dict[d['fields']['dev_eui']] = 1
print(data_dict)
The models are:
class Fleet(models.Model):
fleet_id = models.IntegerField(primary_key=True, unique=True)
fleet_name = models.CharField(max_length=20, unique=True)
class Device(models.Model):
dev_eui = models.CharField(max_length=16, primary_key=True, unique=True)
dev_name = models.CharField(max_length=20, unique=True)
fleet_id = models.ForeignKey(Fleet, on_delete=models.CASCADE)
def __str__(self):
return self.dev_eui
class DevData(models.Model):
data_uuid = models.UUIDField(primary_key=True, default=uuid.uuid1, editable=False)
data_timestamp = models.DateTimeField()
data = models.FloatField()
dev_eui = models.ForeignKey(Device, on_delete=models.CASCADE)
def __str__(self):
return self.dev_eui
Can somebody help me? I imagine that combining two models and some filter should suffice, but I don't know how to do it.

You can annotate the Fleets with the given amount of data, for example:
from django.db.models import Count
Fleet.objects.filter(
device__devdata__data_timestamp__date=today
).annotate(
total_data=Count('device__devdata')
)
The Fleet objects that arise from this queryset will have an extra attribute .total_data that contains the total amount of data for today.

Reference multiple foreign keys in Django Model

I'm making a program that helps log missions in a game. In each of these missions I would like to be able to select a number of astronauts that will go along with it out of the astronauts table. This is fine when I only need one, but how could I approach multiple foreign keys in a field?
I currently use a 'binary' string that specifies which astronauts are to be associated with the mission (1 refers to Jeb, but not Bill, Bob, or Val and 0001 means only Val), with the first digit specifying the astronaut with id 1 and so forth. This works, but it feels quite clunky.
Here's the model.py for the two tables in question.
class astronauts(models.Model):
name = models.CharField(max_length=200)
adddate = models.IntegerField(default=0)
experience = models.IntegerField(default=0)
career = models.CharField(max_length=9, blank=True, null=True)
alive = models.BooleanField(default=True)
def __str__(self):
return self.name
class Meta:
verbose_name_plural = "Kerbals"
class missions(models.Model):
# mission details
programid = models.ForeignKey(programs, on_delete=models.SET("Unknown"))
missionid = models.IntegerField(default=0)
status = models.ForeignKey(
missionstatuses, on_delete=models.SET("Unknown"))
plan = models.CharField(max_length=1000)
# launch
launchdate = models.IntegerField(default=0)
crewmembers = models.IntegerField(default=0)
# recovery
summary = models.CharField(max_length=1000, blank=True)
recdate = models.IntegerField(default=0)
def __str__(self):
return str(self.programid) + '-' + str(self.missionid)
class Meta:
verbose_name_plural = "Missions"
I saw a post about an 'intermediate linking table' to store the crew list but that also isn't ideal.
Thanks!

This is the use case for Django's ManyToManyField. Change the appropriate field on the missions:
class missions(models.Model):
crewmembers = models.ManyToManyField('astronauts')
You can access this from the Astronaut model side like so:
jeb = astronaut.objects.get(name='Jebediah Kerman')
crewed_missions = jeb.missions_set.all()
Or from the mission side like so:
mission = missions.objects.order_by('?')[0]
crew = mission.crewmembers.all()
This creates another table in the database, in case that is somehow a problem for you.

Django filter only on aggregate/annotate

I'm trying to construct a fairly complicated Django query and I'm not making much progress. I was hoping some wizard here could help me out?
I have the following models:
class Person(models.Model):
MALE = "M"
FEMALE = "F"
OTHER = "O"
UNKNOWN = "U"
GENDER_CHOICES = (
(MALE, "Male"),
(FEMALE, "Female"),
(UNKNOWN, "Other"),
)
firstName = models.CharField(max_length=200, null=True, db_column="firstname")
lastName = models.CharField(max_length=200, null=True, db_column="lastname")
gender = models.CharField(max_length=1, choices=GENDER_CHOICES, default=UNKNOWN, null=True)
dateOfBirth = models.DateField(null=True, db_column="dateofbirth")
dateInService = models.DateField(null=True, db_column="dateinservice")
photo = models.ImageField(upload_to='person_photos', null=True)
class SuccessionTerm(models.Model):
originalName = models.CharField(max_length=200, null=True, db_column="originalname")
description = models.CharField(max_length=200, blank=True, null=True)
score = models.IntegerField()
class Succession(model.Model):
position = models.ForeignKey(Position, to_field='positionId', db_column="position_id")
employee = models.ForeignKey(Employee, to_field='employeeId', db_column="employee_id")
term = models.ForeignKey(SuccessionTerm)
class Position(models.Model):
positionId = models.CharField(max_length=200, unique=True, db_column="positionid")
title = models.CharField(max_length=200, null=True)
# There cannot be a DB constraint, as that would make it impossible to add the first position.
dottedLine = models.ForeignKey("Position", to_field='positionId', related_name="Dotted Line",
null=True, db_constraint=False, db_column="dottedline_id")
solidLine = models.ForeignKey("Position", to_field='positionId', related_name="SolidLine",
null=True, db_constraint=False, db_column="solidline_id")
grade = models.ForeignKey(Grade)
businessUnit = models.ForeignKey(BusinessUnit, null=True, db_column="businessunit_id")
functionalArea = models.ForeignKey(FunctionalArea, db_column="functionalarea_id")
location = models.ForeignKey(Location, db_column="location_id")
class Employee(models.Model):
person = models.OneToOneField(Person, db_column="person_id")
fte = models.IntegerField(default=100)
dataSource = models.ForeignKey(DataSource, db_column="datasource_id")
talentStatus = models.ForeignKey(TalentStatus, db_column="talentstatus_id")
retentionRisk = models.ForeignKey(RetentionRisk, db_column="retentionrisk_id")
retentionRiskReason = models.ForeignKey(RetentionRiskReason, db_column="retentionriskreason_id")
performanceStatus = models.ForeignKey(PerformanceStatus, db_column="performancestatus_id")
potential = models.ForeignKey(Potential, db_column="potential_id")
mobility = models.ForeignKey(Mobility, db_column="mobility_id")
currency = models.ForeignKey(Currency, null=True, db_column="currency_id")
grade = models.ForeignKey(Grade, db_column="grade_id")
position = models.OneToOneField(Position, to_field='positionId', null=True,
blank=True, db_column="position_id")
employeeId = models.CharField(max_length=200, unique=True, db_column="employeeid")
dateInPosition = models.DateField(null=True, db_column="dateinposition")
Now, what I want is for each employee to get the position title, the person's name, and for each succession term (of which there are three) how many times the position of that employee is in the succession table, and the number of times each of these employees occurs in the successors table. Above all, I want to do all of this in a singe query (or more specifically, a single Django ORM statement), as I'm doing this in a paginated way, but I want to be able to order the result on any of these columns!
So far, I have this:
emps = Employee.objects.all()
.annotate(ls_st=Count('succession__term'))
.filter(succession__term__description="ShortTerm")
.order_by(ls_st)
.prefetch_related('person', 'position')[lower_limit:upper_limit]
This is only one of the succession terms, and I would like to extend it to all terms by adding more annotate calls.
My problem is that the filter call works on the entire query. I would like to only filter on the Count call.
I've tried doing something like Count(succession__term__description'="ShortTerm") but that doesn't work. Is there any other way to do this?
Thank you very much in advance,
Regards,
Linus

So what you want is a count of each different type of succession__term? That is pretty complex, and I don't think you can do this with the built in django orm right now. (unless you did a .extra() query)
In django 1.8, I believe you will be able to do it with the new Query Expressions (https://docs.djangoproject.com/en/dev/releases/1.8/#query-expressions). But of course 1.8 isn't released yet, so that doesn't help you.
In the meantime, you can use the very handy django-aggregate-if package. (https://github.com/henriquebastos/django-aggregate-if/, https://pypi.python.org/pypi/django-aggregate-if)
With django-aggregate-if, your query might look like this:
emps = Employee.objects.annotate(
ls_st=Count('succession__term', only=Q(succession__term__description="ShortTerm")),
ls_lt=Count('succession__term', only=Q(succession__term__description="LongTerm")), # whatever your other term descriptions are.
ls_ot=Count('succession__term', only=Q(succession__term__description="OtherTerm"))
)
.order_by('ls_st')
.prefetch_related('person', 'position')[lower_limit:upper_limit]
Disclaimer: I have never used django-aggregate-if, so I'm not entirely sure if this will work, but according the the README, it seems like it should.

django querying from 3 models

My models are :
model 1:
class source_of_enquiry(models.Model):
source_of_enquiry = models.CharField(max_length=200, null=True, blank=True)
def __unicode__(self):
return '%s' % self.source_of_enquiry
model 2:
class customers(models.Model):
cutomer_name = models.CharField(max_lentgth=200)
customer_src_n_type = models.Foreign_key(source_of_enquiry)
customer_contact = models.CharField(max_lentgth=200)
def __unicode__(self):
return '%s' % self.customer_name
model 3:
class sales_cycle(models.Model):
item_name = models.CharField(max_length=200)
customer_name = models.Foreignkey(customers)
def __unicode__(self):
return '%s' % self.item_name
how should i know how many sales had peen completed based on source of enquiry??
tried many from `select_related' and 'prefetch_selected' , but all were kaput.

First of all - python naming convention state that classes should not have underscores and prefer upper-case letters instead. So your models should be SourceEnquiry, Customer (not plural) and SaleCycle.
That being said, let's say I have a SourceEnquiry item (I'm going to pick one arbitrarily), and you want all related SaleCycle items, you do it like so:
>>> sinq = SourceEnquiry.objects.get(pk=1)
>>> SaleCycle.objects.all().filter(customer_name__customer_src_n_type=sinq)
p.s.
also, going back to the naming convention thing, it's redundant to use customer as part of a field name inside the class Customer. You alread know it's a customer object, so it's better to name it like so:
class Customer(models.Model):
name = models.CharField(max_lentgth=200)
src_n_type = models.Foreign_key(source_of_enquiry)
contact = models.CharField(max_lentgth=200)
You other fields can also be cleaner:
class SourceEnquiry(models.Model):
value = models.CharField(max_length=200, null=True, blank=True)
class SaleCycle(models.Model):
item = models.CharField(max_length=200)
customer = models.Foreignkey(Customer)