Django inventory app tool cart update view - django

Question

I'm making an inventory app to control the existence of tools in my workshop. Besides knowing how many things I have, I want to know where things are (what tool cart the tool is in ) and who owns the tool cart (Employee). I also need to keep a record of all damaged tools. I've been going about this in the following way:
1.- I have a model called Item that has all common filed for all tools, then I create a new model per tool type with specific field for each tool type i.e.(end-mill-cutters, drill-bits, screws, etc ). these tool Type models all inherit from Item as Multi-table inheritance.
2.- I made the models for my tools carts and its called Carritos( in spanish) this table has a One To One relation ship to Employees( since a carrito can be owned by one person only). It also has a Many To Many relationship to my Item table trough a secondary model called Transaccion, this model handles make the relation between Carrito and Items
this is the Carritos model
class Carritos(models.Model):
no_carrito = models.CharField(max_length=3, unique=True)
empleado = models.OneToOneField(Empleados, on_delete=models.CASCADE)
# empleado = models.ManyToManyField(Empleados, through='Transaccion')
items = models.ManyToManyField(Item, through='Transaccion', related_name='carritos')
f_creacion = models.DateTimeField(auto_now_add=True)
f_actualizacion = models.DateTimeField(auto_now=True)
activo = models.BooleanField(default=True)
def get_absolute_url(self):
return reverse('inventario:carrito')#, kwargs={'pk': self.pk})
class Meta:
verbose_name_plural = "Carritos"
def __str__(self):
return self.no_carrito
class Transaccion(models.Model):
carrito = models.ForeignKey(Carritos, on_delete=models.CASCADE, related_name='items_carrito')
herramienta = models.ForeignKey(Item, on_delete=models.CASCADE, related_name='items_carrito')
cantidad = models.PositiveSmallIntegerField(default=1)
activo = models.BooleanField(default=True)
tipo = models.CharField(max_length=10, choices=CONSUMIBLE, blank=True, null=True)
motivo = models.CharField(max_length=10, blank=True, null=True)
def get_absolute_url(self):
return reverse('inventario:carrito')#, kwargs={'pk': self.pk})
3.- The idea I had to get the carritos logic is to get a list of existing carts in the carts main page and have a button bind to a CreateView CBV to create a new carrito if needed.
This list would also have a button bind to an UpdateView CBV in order to be able to change the employee in case the employee quits and an other button bind to a function that in theory would work as a DetailView to see all data assigned to carrito like (employee assigned to it, carrito number, and all Items in the carrito).
My intention was to be able to add an Item inside this view and have all items listed, I managed to be able to add Items and also managed to display all Items and the amount of those Items the carrito has. I had some issues on how to go about when multiple items of the same kind needed to be added to the carrito (let's say I needed to add 2 cutters exactly the same). But I figured that since I all ready had the Transaccion table, and this table tied Item to Carritos. I could use this to record every items as 1 of each and have an active field as Boolean, this way I could display and aggregate all distinct items and sum totals of every item in my view. It works for displaying the quantities.
The problem I'm currently are having, is if I want to edit a tool type and deactivate one of the items in the transaction model I always get the firs items on the list no matter how I choose to filter it.
My views for carritos creation
# =========================================================================== #
# LOGICA PARA CREAR CARRITOS
# =========================================================================== #
# ===================> Logica relacinado con Cortadores <=====================#
def home_carrito(request):
template_name = 'inventario/carrito/createcarrito.html'
model = Carritos
carritos = Carritos.objects.all()
if carritos:
return render(request, template_name, {'carritos':carritos})
else:
return render(request,template_name)
class CarritoCreate(CreateView):
model = Carritos
fields = [
'no_carrito',
'empleado',
'activo',
]
class ItemCreate(CreateView):
model = Transaccion
fields = [
'carrito',
'herramienta',
]
def detalle_carrito(request, pk):
model = Carritos, Transaccion
template_name = 'inventario/carrito/detalles_carrito.html'
carritos = Carritos.objects.filter(pk=pk)
# GEST ALL TOOLS ASSIGNE TO CARRITO'S PK THAT ARE ACTIVE
# TRY TO GET ALL ACTIVE ITEMS THAT BELONG TO CARRITO = PK AND AGREGATE TOTAL ITEMS PER TYPE
cantidades = Transaccion.objects.values('herramienta__description').annotate(Sum('cantidad')).filter(activo=True, carrito_id=pk)
# GEST ALL TOOLS ASSIGNE TO CARRITO'S PK THAT ARE NOT ACTIVE
eliminados = Transaccion.objects.filter(activo=False,carrito_id=pk)
return render(request,template_name, {'carrito':carritos, 'trans':cantidades, 'eliminados':eliminados})
class CarritoUpdate(UpdateView):
model = Carritos
fields = [
'no_carrito',
'empleado',
'activo',
]
template_name_suffix = '_update_form'
def ItemUpdate(UpdateView):
model = Transaccion
fields = [
'carrito',
'herramienta',
'cantidad',
'tipo',
'motivo',
'activo',
]
template_name_suffix = '_update_form'
def detalle_Items(request, pk):
model = Transaccion
template_name = 'inventario/carrito/test-template.html'
try:
items_update = Transaccion.objects.filter(activo=True, carrito_id=pk, herramienta_id=pk)
except Transaccion.DoesNotExist:
raise Http404()
return render(request, template_name, {'items_update':items_update})
So what I need in the first place is to know if what I'm doing is logical? or make sense. Scond thing I need is to know if there a better way and how?
and finally I need help resolving my issue: I need to get into an updateview for every Item in my Transaccion model and be able to disable or enable that record.

Answer 1

Different people would take different approaches. So far I think what you have built would absolutely work, but what becomes complicated is building the realtime inventories, which looks like its built from the transaction log. What I see as missing from the model is the snapshot of real time inventories available. Because we aren't talking about a data model that changes so frequently - like ad impressions - you can store that upon transaction vice computing it as needed.
For instance, your global inventory of hammers is 5 hammers. One employee adds a hammer to a cart. From here you articulated a couple of different use cases. One is that you need to know that employee XYZ (which implies a specific cart based on the 1-to-1) has that specific hammer. What you'd also like to know is how many hammers you have available? You may also want to understand the turnover of specific assets. Does employee XYZ maintain items in his cart longer than the average employee?
To do this I think you'd need to talk about the API layer which orchestrates that logic and the addition of another object which snapshots actual inventory instead of computing that from the transaction log. Why I bring up the API layer is that it may be a cleaner abstraction to place the logic for orchestrating multiple model changes in that than having the model itself house that logic.
So in short, I think what you've built works - but the logical expression of the use cases you've articulated are handled at the viewset/ modelviewset layer in an API. Because thats where you'll need to prep the data to be loaded into a specific format for visualization. And thats where what is easily serializable becomes the dominant force in model complexity.