cmsmanage/rentals/models.py

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from django.contrib.auth import get_user_model
from django.core import validators
from django.db import models
class LockerBank(models.Model):
"""A set of locker units, placed together"""
name = models.CharField(max_length=200)
location = models.CharField(max_length=200)
slug = models.SlugField(unique=True)
def __str__(self):
return f"{self.name} ({self.units.count()} units)"
class LockerUnit(models.Model):
"""A standalone set of lockers"""
bank = models.ForeignKey(
LockerBank, on_delete=models.SET_NULL, related_name="units", null=True
)
index = models.PositiveIntegerField()
first_letter = models.CharField(
max_length=1, validators=[validators.RegexValidator("[A-Z]")], unique=True
)
first_number = models.PositiveIntegerField()
rows = models.PositiveIntegerField(default=5)
columns = models.PositiveIntegerField(default=2)
class Meta:
# TODO: add constraint to check for letter overlaps
constraints = [
models.UniqueConstraint(fields=["bank", "index"], name="unique_bank_index")
]
ordering = ["index"]
def letter_for_column(self, column: int) -> str:
return chr(column + ord(self.first_letter))
def number_for_locker(self, column: int, row: int) -> int:
return row + self.first_number + column * self.rows
@property
def iter_doors(self):
for row in range(self.rows):
for column in range(self.columns):
# TODO: filter could be optimized
yield (
self.letter_for_column(column),
self.number_for_locker(column, row),
self.rentals.filter(row=row, column=column),
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)
# TODO: add check constraint to ensure that column and number are within locker_unit bounds
# TODO: add unique constraint on (unit, row, column)?
class LockerRental(models.Model):
"""A rental of a single locker"""
locker_unit = models.ForeignKey(
LockerUnit, on_delete=models.CASCADE, related_name="rentals"
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)
column = models.PositiveIntegerField()
row = models.PositiveIntegerField()
user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
@property
def address(self) -> str:
letter = self.locker_unit.letter_for_column(self.column)
number = self.locker_unit.number_for_locker(self.column, self.row)
return f"{self.locker_unit}-{letter}{number}"
def __str__(self):
return f"{self.user}: {self.address}"