models.py

from pyexpat import model
from tabnanny import verbose
from django.db import models
from django.contrib.auth import get_user_model
from tienda.models import Producto
from django.db.models import F, Sum, FloatField

User = get_user_model()

class Pedido(models.Model):
    user = models.ForeignKey(User, on_delete= models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.id

    @property
    def total(self):
        return self.lineapedido_set.aggregate(
            total=Sum(F("precio")*F("cantidad"),output_field = FloatField())
        )["total"]

    class Meta:
        db_table = 'pedidos'
        verbose_name = 'pedido'
        verbose_name_plural = 'pedidos'
        ordering = ['id']

class LineaPedido(models.Model):
    user = models.ForeignKey(User, on_delete= models.CASCADE)
    producto_id = models.ForeignKey(Producto, on_delete= models.CASCADE)
    pedido_id = models.ForeignKey(Pedido, on_delete= models.CASCADE)
    cantidad = models.IntegerField(default=1)
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f'{self.cantidad} Unidades de {self.producto_id.nombre}'

    class Meta:
        db_table = 'lineapedidos'
        verbose_name = 'lineapedido'
        verbose_name_plural = 'lineapedidos'
        ordering = ['id']