Verify a Django model field inside a Django model - python

I have a Django model called Attendance that has the clock in and clock in times of an employee along with the status of that entry, to see whether it's authorized or not. I then, am making another model called Payroll. I want this to check inside the Attendance entries to see all the Authorized entries and then do some action on them. How do I check all the status fields for all the entries in Attendance?
EDIT: Updated to better elaborate my question.
To better elaborate my question, this is how I've setup my Attendance model:
class CWorkAttendance(models.Model):
AUTO_ATT = "AU"
MANUAL_ATT = "MA"
WORK_ENTRY_TYPES = (
(AUTO_ATT, "Auto-Attendance"),
(MANUAL_ATT, "Manual-Attendance"),
)
AUTHORIZED = "AU"
UNAUTHORIZED = "UA"
WORK_ENTRY_STATUSES = (
(AUTHORIZED, "Athorized"),
(UNAUTHORIZED, "Un-Authorized"),
)
#Thank you motatoes
def face_locations_in(self, instance):
now = datetime.datetime.now()
return "attendance/{}/{}/in".format(instance.work_employee, now.strftime("%Y/%m/%d"))
def face_locations_out(self, instance):
now = datetime.datetime.now()
return "attendance/{}/{}/out".format(instance.work_employee, now.strftime("%Y/%m/%d"))
work_employee = models.ForeignKey('CEmployees', on_delete=models.CASCADE,)
work_start_time = models.DateTimeField()
work_end_time = models.DateTimeField(null=True)
work_duration = models.IntegerField(null=True)
work_entry_type = models.CharField(max_length=2,choices=WORK_ENTRY_TYPES)
work_entry_status = models.CharField(max_length=2, choices=WORK_ENTRY_STATUSES, default=WORK_ENTRY_STATUSES[1][0])
employee_face_captured_in = models.ImageField(upload_to=face_locations_in,)#////////
employee_face_captured_out = models.ImageField(upload_to=face_locations_out,)
If you look closely at the work_entry_status, it's a choice CharField that will contain the status of the entry (UNAUTHORIZED by default).
I want to create a Payroll model that will check for all the rows in the CWorkAttendance model and check their work_entry_status fields to see if they are Authorized, which is what I want to learn how to do.
If those fields are authorized, I want the grab the row's work_employee, work_duration and also some details from the original CEmployees row for the employee.
This is what I want my Payslip/Payroll model to look like:
class Payslip(models.Model):
GENERATED = "GEN"
CONFIRMED = "CON"
PAYSLIP_STATUS = (
(GENERATED, "Generated-UNSAVED"),
(CONFIRMED, "Confirmed-SAVED"),
)
payslip_number = models.IntegerField()#MM/YY/AUTO_GENERATED_NUMBER(AUTO_INCREMENT)
payslip_employee = models.ForeignKey('CEmployees', on_delete=models.CASCADE,)#Choose the employee from the master table CEmployees
payslip_generation_date = models.DateTimeField(default=datetime.datetime.now())#Date of the payroll generation
payslip_total_hours = models.IntegerField()#Total hours that the employee worked
payslip_from_date = models.DateField()"""The date from when the payslip will be made. The payslip will be manual for now, so generate it after choosing a a date to generate from."""
payslip_total_basic_seconds = models.IntegerField()#Total seconds the employee worked
payslip_total_ot_seconds = models.IntegerField()#Total overtime seconds the employee worked
payslip_basic_hourly_rate = models.IntegerField()#The basic hourly rate of the employee mentioned here. Take from the master employees table.
payslip_basic_ot_rate = models.IntegerField()#Taking the basic overtime rate from the master table
payslip_total_amount = models.FloatField()#The total amount of the payslip
payslip_entry_status = models.CharField(max_length=3, default=GENERATED)#The status of the pay slip.
Thanks,

Not sure if I understand your requirements well, so let me know if I misunderstood.
# `employee` is the work_employee in question
# if you don't want to filter by employee, remove `work_employee=employee`
attendances = CWorkAttendance.objects.filter(work_entry_status=CWorkAttendance.AUTHORIZED, work_employee=employee)
for attendances in attendances:
# do things with this attendance record
attendance.work_duration
attendance.employee
# ....
Update
Since you would like to do it manually, I would suggest having a separate view to generate the Payslip. The important thing is to know the date_from and the date_to for this payslip. I imagine that it is the managers who would have access to this view, so you would need the proper access controls set for it. I also think you need to have a payslip_to_date even if you are going to generate it until the current date, which will be useful for record keeping. I assume you have that column in the code below.
views.py:
from django.views import View
class GeneratePayslip(View):
"""
make sure you have the right access controls set to this view
"""
def post(self, request, **kwargs):
employee_id = kwags.POST.get("employee_id")
date_from = kwargs.POST.get("from_date")
date_to = kwargs.POST.get("to_date")
# we fetch all the objects within range
attendances = CWorkAttendance.objects.filter( \
work_entry_status=CWorkAttendance.AUTHORIZED, \
work_employee_id=employee_id, \
work_start_time__gte=date_from, \
work_end_time__lte=date_to \
)
hours = 0
for attendance in attendances:
# perform calculations to compute total sum and rate
pass
# create the payslip object here ..
# redirect to a success page and return
If you wanted to do it automatically later on, you may want to generate payslips automatically, once a month. For that you could use something like Celery to have periodic tasks that run in the background, for each employee. If this is the case you could move the above code to a file such as utils.py. you can create a method which takes employee_id, from_date, to_date, and then generate the payslip object, returning the payslip_id to the calling method

Related

How to change dates when filtering a queryset in Django?

I want to display a list of all payments done by the company. But I want to be able to filter the dates, only showing payments for example:
In the last 30 days
In the last 90 days
Between two specific dates
Now, I know I can filter in my views between two dates, or before today for example.
But how I can I do this using something like a dropdown or a Data chooser on the template?
Something like this for reference.
For reference, the payments model would be this:
class Payment(models.Model):
name = models.CharField(max_length=250)
date = models.DateField(default=datetime.now)
value = models.DecimalField(max_digits=10, decimal_places=2, validators=[MinValueValidator(0.00)])
Use django forms with choice field and based on the value filter your queryset. e.g:
Choices:
PERIOD_LAST_THREE_MONTHS = "last-three-months"
PERIOD_LAST_SIX_MONTHS = "last-six-months" # ..
PERIOD_CHOICES = (
(PERIOD_LAST_THREE_MONTHS, _("Last 3 Months")),
(PERIOD_LAST_SIX_MONTHS, _("Last 6 Months")), ..
)
NOTE: variables separated with hyphens because they will be used in query string of http request.
Utils:
def get_period_date(period):
if period == PERIOD_LAST_THREE_MONTHS:
return timezone.now() - timezone.timedelta(days=90)
elif period == PERIOD_LAST_SIX_MONTHS:
return timezone.now() - timezone.timedelta(days=180)
This function will return a datetime object to filter your queryset with.
Forms:
class DateForm(forms.Form):
period = forms.ChoiceField(choices=PERIOD_CHOICES, required=False)
View:
class PaymentFormView(base.TempleView):
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context['payments'] = Payment.objects.filter(date__gte=get_period_date(self.request.GET('period'))
return context
So basically based on the form value we get a date time object and filtered the queryset(Remember you have a date object). I have used template view instead of form view because I assume you do not want to accept post request. But again you can use form view and not allow post methods, this is up to you(It can be also done with function based views). Also consider the possibility that form can be empty so query string in http request may not have the period argument that may cause error and handle this situations how every you like.

Django: How to access the previous model class instances while creating new instance of the same class?

I have a model in my django app like below:
models.py
class Profit(models.Model):
client = models.ForeignKey(Client, null=True, on_delete=models.CASCADE)
month = models.CharField(max_length=100)
amount = models.IntegerField()
total_profit = models.IntegerField()
Now, what I want to do is that whenever a new instance/object is created for this class, the user puts the month and the amount of profit for that month, But I want that it also calculates the total profit the user got up till the current profit, by adding all the profits that was being added in the past.
For example.
if the user is adding the profit for month April, then it add all the values in the amount field of previously added objects of (March, February, January and so on..) and put it in the field total_profit. So that the user can see how much total_profit he got at each new entry.
My views.py where I am printing the list of profits is given below:
views.py
class ProfitListView(ListView):
model = Profit
template_name = 'client_management_system/profit_detail.html'
context_object_name = 'profits'
# pk=self.kwargs['pk'] is to get the client id/pk from URL
def get_queryset(self):
user = get_object_or_404(Client, pk=self.kwargs['pk'])
return Profit.objects.filter(client=user)
Client is the another model in my models.py to which the Profit class is connected via ForeignKey
I also don't exactly know how to use window functions inside this view.
As stated in the comments one should generally not store things in the database that can be calculated from other data. Since that leads to duplication and then makes it difficult to update data. Although if your data might not change and this is some financial data one might store it anyway for record keeping purposes.
Firstly month as a CharField is not a very suitable field of yours for your schema. As firstly they are not easily ordered, secondly it would be better for you to work with a DateTimeField instead:
class Profit(models.Model):
month = models.CharField(max_length=100) # Remove this
made_on = models.DateTimeField() # A `DateTimeField` is better suited
amount = models.IntegerField()
total_profit = models.IntegerField()
Next since you want to print all the Profit instances along with the total amount you should use a Window function [Django docs] which will be ordered by made_on and we will also use a frame just in case that the made_on is same for two entries:
from django.db.models import F, RowRange, Sum, Window
queryset = Profit.objects.annotate(
total_amount=Window(
expression=Sum('amount'),
order_by=F('made_on').asc(),
frame=RowRange(end=0)
)
)
for profit in queryset:
print(f"Date: {profit.made_on}, Amount: {profit.amount}, Total amount: {profit.total_amount}")

Django: Transactions and how to avoid wrong counting?

I am currently struggling with a topic connected to transactions. I implemented a discount functionality. Whenever a sale is made with a discount code, the counter redeemed_quantity is increased by + 1.
Now I thought about the case. What if one or more users redeem a discount at the same time? Assuming redeemed_quantity is 10. User 1 buys the product and redeemed_quantity increases by +1 = 11. Now User 2 clicked on 'Pay' at the same time and again redeemed_quantity increases by +1 = 11. Even so, it should be 12. I learned about #transaction.atomic but I think the way I implemented them here will not help me with what I am actually trying to prevent. Can anyone help me with that?
view.py
class IndexView(TemplateView):
template_name = 'website/index.html'
initial_price_of_course = 100000 # TODO: Move to settings
def check_discount_and_get_price(self):
discount_code_get = self.request.GET.get('discount')
discount_code = Discount.objects.filter(code=discount_code_get).first()
if discount_code:
discount_available = discount_code.available()
if not discount_available:
messages.add_message(
self.request,
messages.WARNING,
'Discount not available anymore.'
)
if discount_code and discount_available:
return discount_code, self.initial_price_of_course - discount_code.value
else:
return discount_code, self.initial_price_of_course
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context['stripe_pub_key'] = settings.STRIPE_PUB_KEY
discount_object, course_price = self.check_discount_and_get_price()
context['course_price'] = course_price
return context
#transaction.atomic
def post(self, request, *args, **kwargs):
stripe.api_key = settings.STRIPE_SECRET_KEY
token = request.POST.get('stripeToken')
email = request.POST.get('stripeEmail')
discount_object, course_price = self.check_discount_and_get_price()
charge = stripe.Charge.create(
amount=course_price,
currency='EUR',
description='My Description',
source=token,
receipt_email=email,
)
if charge.paid:
if discount_object:
discount_object.redeemed_quantity += 1
discount_object.save()
order = Order(
total_gross=course_price,
discount=discount_object
)
order.save()
return redirect('website:index')
models.py
class Discount(TimeStampedModel):
code = models.CharField(max_length=20)
value = models.IntegerField() # Smallest currency unit, as amount charged
max_quantity = models.IntegerField()
redeemed_quantity = models.IntegerField(default=0)
def available(self):
available_quantity = self.max_quantity - self.redeemed_quantity
if available_quantity > 0:
return True
class Order(TimeStampedModel):
total_gross = models.IntegerField()
discount = models.ForeignKey(
Discount,
on_delete=models.PROTECT, # Can't delete discount if used.
related_name='orders',
null=True,
You can pass the handling of the incrementation to the database in order to avoid the race condition in your code by using django's F expression:
from django.db.models import F
# ...
discount_object.redeemed_quantity = F('redeemed_quantity') + 1
discount_object.save()
From the docs with a completely analogous example:
Although reporter.stories_filed = F('stories_filed') + 1 looks like a normal Python assignment of value to an instance attribute, in fact it’s an SQL construct describing an operation on the database.
When Django encounters an instance of F(), it overrides the standard Python operators to create an encapsulated SQL expression; in this case, one which instructs the database to increment the database field represented by reporter.stories_filed.
Django is a piece of a synchronous code. It means that every request you make to the server is processed individually. This problem could arise, when there are multiple server-workers (for example uwsgi workers), but again - it's practically impossible to do this. We run a webshop application with multiple workers and something like this never happend.
But back to the question - if you want to query the database to increase a value by one, see schwobaseggl's answer.
The last thing is that I think you misunderstand what transaction.atomic() does. Simply put it rolls back any queries made to the database in a function if function exits with an error to the state when function was called. See this answer and this piece of documentation. Maybe it will clear some things up.

Filter objects in Django 2 if all objects in subquery have specific value

I have the follow models:
class FactoryDevice(models.Model)
...
class InspectionRegister(models.Model)
factory_device = models.ForeignKey(FactoryDevice)
inspection_date = models.DateTimeField()
status = models.CharField(choices=choices.STATUS)
This is the scenario:
In a factory, every week devices are inspected.
I want filter only FactoryDevices that the last five related InspectionRegisters have status as choices.REPPROVED. If one of the last five InspectionRegister in a FactoryDevice not has status as choices.REPPROVED so this FactoryDevice must not be in the results.
First off, I would define a related_name for your reverse relationship to make your life easier:
factory_device = models.ForeignKey(FactoryDevice, related_name='inspections')
Then something like this could work:
queryset = FactoryDevice.objects
.prefetch_related(Prefetch(
'inspections', # your related name
InspectionRegister.objects.order_by('-inspection_date')[:5].filter(status=choices.REPPROVED),
to_attr='failed_inspections'
)
.annotate(failed_count=Count('failed_inspections'))
)
.filter(failed_count__gte=5)

Django model history by date and datetime

Assume I have model like this:
class Account(models.Model):
balance = models.IntegerField()
debt = models.IntegerField()
history = HistoricalRecords()
I'm using django-simple-history to get instance of the model as it would have existed at the provided date and time:
inst = Account.history.as_of(datetime.datetime.now().date)
It's working fine, but I want to get instance where balance field is represented as it would have existed at the provided date and time, and then debt field will be most recent of that date. I don't know if this is possible, didn't find anything about that.
The history ORM will return back a model based off of the one you submitted, as it existed at that point in time.
account = Account.objects.create(balance=1, debt=1)
account.save()
history_obj = account.history.last()
print(history_obj.debt) # returns 1
account.debt = 222
account.save()
new_history_obj = account.history.last()
print(new_history_obj.debt) # returns 222
Assuming you're using the Account.history.as_of() method to return the history object that you intend to be reading from, you could do this:
yesterday = datetime.datetime.now() - datetime.timedelta(days=1)
history_obj = Account.history.as_of(yesterday)
print(history_obj.debt) # returns not the current debt, but the debt as-of yesterday
Unless I'm misunderstanding what you're hoping to accomplish, you could just do this with what you have in your question:
inst = Account.history.as_of(datetime.datetime.now().date)
print(inst.debt)

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