Django Models custom methods - django

Question

is there any way to call a specific model custom method from a view? i need to subtract or increment depending on the view a field on my model, I want to create a button for each of the two options and after imputing that data update the field in my database. if so how can i go about implementing it, currently my save method is doing the two operations at once
models.py
class Items(models.Model):
nombre = models.CharField(max_length=250)
descripcion = models.CharField(max_length=250)
codigo_proveedor = models.CharField(max_length=250)
categoria = models.ForeignKey('Categorias', on_delete=models.CASCADE)
c_minima = models.PositiveIntegerField()
c_actual = models.PositiveIntegerField()
c_descuento = models.PositiveIntegerField(blank=True)
c_incremento = models.PositiveIntegerField(blank=True)
proveedor = models.ForeignKey('Proveedores', on_delete=models.CASCADE)
carrito = models.ForeignKey('Carrito', on_delete=models.CASCADE, null=True )
p_unitario = models.DecimalField(max_digits=10, decimal_places=2, null=True, blank=True )
total = models.DecimalField(max_digits=10, decimal_places=2, null=True, blank=True)
material = models.ForeignKey(Materiales, null=True, blank=True)
tipo = models.ForeignKey(Tipo, null=True, blank=True)
active = models.BooleanField()
def save(self, *args, **kwargs):
self.c_actual = self.c_actual - self.c_descuento
self.c_actual =self.c_actual + self.c_incremento
self.total = self.c_actual * self.p_unitario
super(Items, self).save(*args, **kwargs)
def __str__(self):
return '%s %s %s %s' % (self.nombre, str(self.categoria), str(self.c_actual), str(self.total))

Answer 1

You could use an instance method on the model e.g. exactly like the get_absolute_url().
You can add 3 methods in the model definition increment, decrement and total and write the respective logic in there.
So the view in the views.py file be something like
def some_view(request, *args, **kwargs):
#read the post data values from req
#create model instance
data = Items( #key value pairs)
#read from req to increament or decrement
if incr:
data.increament()
else:
data.decrement()
data.total()
data.save()
return render( ... )