Estoque Simples OP of Darkness

models.py

from alguma_coisa_do_django import models

TRANSACTION_KIND = (
    ("in", "Entrada"),
    ("out", "Saida"),
    ("eaj", "Entrada de Ajuste"),
    ("saj", "Saída de Ajuste")
)


class Product(models.Model):
    name = models.CharField(max_length=100)
    #deleted = models.BooleanField(default=False)

    def qtd_avaliable(self):
        transactions = self.transactions.all().order_by("date_transactions")
        total_avaliable = 0

        for transaction in transactions:
            if transaction.transaction_kind == 'in' or transaction.transaction_kind == 'eaj':
                total_avaliable += transaction.quantity
            else:
                total_avaliable -= transaction.quantity

        return total_avaliable

    def __unicode__(self):
        return f"Produto {self.name} possuí {self.qtd_avaliable()} em estoque."


class Transaction(models.Model):
    quantity = models.PositiveIntegerField()
    transaction_kind = models.CharFild(max_length=3, choices=TRANSACTION_KIND)
    date_transaction = models.DataTimeField(auto_now=True)
    product = models.ForeignKey(Product, quando_deletar_produto_deleta_aqui=True, related_name="transactions")

    def historico_vendas(self, product, **extra_filter):
        pass

    def historico_entradas(self, product, **extra_filter):
        # transactions
        # estrutura para montar algo \o/
        pass

    def __unicode__(self):
        trans_kind = "Entrada"
        return f"{trans_kind} de {self.quantity} unidades do produto {self.product.name} no dia {self.date_transaction}."


# Passo 1
papel = Product(name="Folha de Papel")
papel.save()
compra_papel = Transaction(quantity=300, transaction_kind="in", product=papel)
compra_papel.save()
papel.qtd_avaliable() # 300
# Fim do Passo 1

# Passo 2
papel = Product.objects.get(name="Folha de Papel")
venda_papel = Transaction(quantity=100, transaction_kind="out", product=papel)
venda_papel.save()
papel.qtd_avaliable() # 200
# Fim do Passo 2

# Edit produto
pacote_papel = Product.objects.get(name="Folha de Papel")
pacote_papel.name = "Pacote de 500 folhas de papel"
pacote_papel.qtd_avaliable() # 200
pacote_papel.save()
pacote_papel.qtd_avaliable() # 200
ajuste = Transaction(quantity=190, transaction_kind="saj", product=pacote_papel)
ajuste.save()
pacote_papel.qtd_avaliable() # 10
# Fim Edit