Reusable views method for multiple model classes Django - django

Question

Guys I want to create a tools inventory app.
I have this method that will do the exact same thing on all tools types. What I want to know is how can I use this method dynamically selecting what models to use (maybe how to pass a model class as an argument).
It's currently working only for one type of tool. My models.py has an abstract model that has all common fields for all tools and then various models that inherit it for tool specific fields (e.i. End mills, Drill-bits, pliers, screwdrivers, etc all inherit common filed from my abstract model).
def calcular_nueva_cantidad(ce, up, get_link):
if get_link == 'incremento':
total = ce + up
else:
total = -(ce - up)
return total
def calcular_nuevo_total(nce, pu):
total = nce * pu
return total
# crea el formulario para la actualizacion de cantidad existente
class updateForm(forms.Form):
update = forms.IntegerField()
def actualizar_cantidad(request, pk, model ):
# trae de la base de datos el valor de la cantidad_existente
cantidad_existente = model.objects.filter(pk=pk).values('cantidad_existente')
c = cantidad_existente.values_list('cantidad_existente', flat=True)
ce = c[0]
# trae de la base de datos el valor de la precio_unitario
precio_unitario = model.objects.filter(pk=pk).values('precio_unitario')
p = precio_unitario.values_list('precio_unitario', flat=True)
pu = p[0]
# trae de la base de datos el valor de la total
qs_total = model.objects.filter(pk=pk).values('total')
if request.method =='POST':
form = updateForm(request.POST)
if form.is_valid():
# Obtiene el name de urls para el link segun sea el caso
get_link = resolve(request.path_info).url_name
get_linkwargs = resolve(request.path_info).kwargs
print(F'========>{get_link, get_linkwargs }<=========')
up = form.cleaned_data['update']
# Calcula el nuevo valor de cantidad existente
nce = calcular_nueva_cantidad(up, ce, get_link)
# Actualiza la nueva cantidad existente
cantidad_existente.update(cantidad_existente=nce)
# Calcula el nuevo valor de cantidad existente
s_total = calcular_nuevo_total(nce, pu)
# Actualiza la nueva cantidad existente
qs_total.update(total=s_total)
# Obteiene item id del tipo de cortador asi puede regresar a la pantalla del listado
pp = model.objects.filter(pk=pk).values('tipo')
ppp = pp.values_list('tipo', flat=True)
pk = ppp[0]
return HttpResponseRedirect(reverse('inventario:cortadores-list', args=(pk, )))
else:
# Redirect to fail page after POST
return HttpResponse('')
else:
form = updateForm()
return render(request, 'inventario/update.html', {'form':form})
This is my abstract class in my models.py
class Item(models.Model):
description = models.CharField(max_length=30,)
numero_parte = models.CharField(max_length=30)
proveedor = models.ForeignKey(Proveedor, on_delete=models.CASCADE)
cantidad_existente = models.PositiveIntegerField()
update = models.PositiveIntegerField(blank=True, default=0)
cantidad_minima = models.PositiveIntegerField()
precio_unitario = models.DecimalField(max_digits=7, decimal_places=2)
total = models.DecimalField(max_digits=7, decimal_places=2, blank=True)
asignado_a = models.ForeignKey(Empleados, on_delete=models.CASCADE, blank=True, null=True)
anaquel = models.CharField(max_length=2, choices=ANAQUEL, blank=True, null=True)
posicion_en_x = models.CharField(max_length=2, blank=True, null=True)
posicion_en_y = models.CharField(max_length=2, blank=True, null=True)
activo = models.BooleanField()
class Meta:
abstract = True
def save(self,*args,**kwargs):
self.total = self.cantidad_existente * self.precio_unitario
super().save(*args,**kwargs)
These two classes inherit from Item
class Cortadores(Item):
tipo = models.ForeignKey(Tipos_Cortadores,on_delete=models.CASCADE)
material = models.ForeignKey(Materiales, on_delete=models.CASCADE)
filos = models.CharField(max_length=5, choices=GABILANES)
diametro = models.ForeignKey(Diametros, on_delete=models.CASCADE)
longitud = models.ForeignKey(Longitud, on_delete=models.CASCADE)
desbaste = models.CharField(max_length=1, choices=DESBASTE)
class Meta:
verbose_name_plural = "Cortadores"
def get_absolute_url(self):
return reverse('inventario:cortadores-list', kwargs={'id': self.tipo.id})
def __str__(self):
return '%s %s %s %s %s %s' % ( str(self.tipo), str(self.material), str(self.filos), str(self.diametro),
self.longitud, self.desbaste
)
class Tornillos(Item):
tipo = models.CharField(max_length=10, choices=TIPO_TORNILLO)
paso = models.ForeignKey(Paso_Tornillo, on_delete=models.CASCADE)
material = models.ForeignKey(Materiales, on_delete=models.CASCADE)
longitud = models.ForeignKey(Longitud, on_delete=models.CASCADE)
class Meta:
verbose_name_plural = "Tornillos"
def get_absolute_url(self):
return reverse('inventario:lista-herramientas-mecanicas')#, kwargs={'pk': self.pk})
def __str__(self):
return '%s %s %s %s' % (str(self.tipo), str(self.paso), str(self.material), str(self.longitud))
I made a class for every tool type that I own. I only included these two classes for simplicity and not fill the post with a lot of code.

Answer 1

If you still can change the design of your tables, you could use multi-table-inheritance instead of the abstract-base-class you are using now.
That would mean that you will have one model Item (which will be an actual database table) and then other models that inherit from this model (their database tables will only hold the new fields, but not repeat any fields).
For that change you only need to remove abstract = True from Item.Meta; you should not need to change other parts form your models. Of course, you will have to drop your tables and run migrations again (will destroy your current data).
As I said, this is only an option if you can still change your database tables significantly.
With this setup, you can query your Item model directly for the common fields. There are some subtleties you have to be careful about, but read the docs I linked to see if it solves your issue.