comet/comet/account/models.py

from django.db import models

from django.utils import timezone


class Account(models.Model):
    """Account for a member."""
    balance = models.DecimalField(
        verbose_name="Solde",
        max_digits=4,
        decimal_places=2,
        default=0
    )
    firstname = models.CharField(max_length=255, verbose_name="Nom")
    lastname = models.CharField(max_length=255, verbose_name="Prénom")
    email = models.EmailField(verbose_name="Email")

    def calc_balance(self):
        """Adjust the ballance according to the sales,
        without saving the model."""
        self.balance = Sale.objects.filter(account=self)\
            .aggregate(models.Sum('price'))['price__sum'] or 0


class Sale(models.Model):
    """Represents a sale"""
    price = models.DecimalField(
        verbose_name="Prix (€)",
        max_digits=5,
        decimal_places=3
    )
    account = models.ForeignKey(Account, on_delete=models.SET_NULL, null=True)
    title = models.CharField(max_length=255, verbose_name="Intitulé")
    date = models.DateTimeField(verbose_name="Date", default=timezone.now)


class Article(models.Model):
    """An article which can be sold."""
    price = models.DecimalField(
        verbose_name="Prix unitaire (au €/g)",
        max_digits=4,
        decimal_places=3
    )
    name = models.CharField(
        max_length=255,
        verbose_name="Désignation"
    )

    def __str__(self):
        return ' '.join([self.name, str(self.price), '€/g'])