nummi/nummi/main/models.py

import uuid
from django.db import models
from django.forms import ModelForm


class Category(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=64)
    parent = models.ForeignKey("self", on_delete=models.SET_NULL, blank=True, null=True)

    def __str__(self):
        return self.name


class Transaction(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=256)
    description = models.TextField()
    value = models.DecimalField(max_digits=12, decimal_places=2)
    date = models.DateField()
    category = models.ForeignKey(
        Category, on_delete=models.SET_NULL, blank=True, null=True
    )

    def __str__(self):
        res = f"{self.date} {self.name}: {self.value}€"
        if self.category:
            return f"{res} ({self.category})"
        return res


class TransactionForm(ModelForm):
    class Meta:
        model = Transaction
        fields = ["name", "description", "value", "date", "category"]


class Invoice(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=256)
    file = models.FileField(upload_to="invoices/")
    transaction = models.ForeignKey(Transaction, on_delete=models.CASCADE)

    def __str__(self):
        return f"{self.name}: {self.transaction}"

    def delete(self, *args, **kwargs):
        self.file.delete()
        super().delete(*args, **kwargs)


class InvoiceForm(ModelForm):
    class Meta:
        model = Invoice
        fields = ["name", "file"]