Thanks Andréas, very helpful!
One more question -
Since I'm using class based views and this view requires 2 models I'm
unsure how to fetch the data from both the models to use in the same view.
It looks like I need to modify the get_context_data() method but I'm unsure
how to filter this way. Here is my view now
class PurchaseOrderDetailView(LoginRequiredMixin, TemplateView):
#context_object_name = "po"
#model = PurchaseOrder
template_name = 'financial/purchase_orders/purchase_order_detail.html'
def get_context_data(self, **kwargs):
context = super(PurchaseOrderDetailView, self).get_context_data(**
kwargs)
context['purchase_order'] = PurchaseOrder.objects.get()
context['item'] = PurchaseOrderItem.objects.all()
return context
So basically what I'm trying to do is filter the
PurchaseOrder.objects.get() so that the purchase_order.pk = the pk in the
url, and then filter the PurchaseOrderItem.objects.get() so that the
item.po_number_fk = purchase_order.pk
Thanks again for all your help!
On Friday, August 3, 2018 at 1:44:15 AM UTC-6, Andréas Kühne wrote:
>
> Hi,
>
> I think you are doing it right. I would remove the PurchaseOrderTotal
> model however. The reason for this is that the purchase order itself should
> know it's total and so on. Either you can add a signal on the save of the
> PurchaseOrderItem - and update the PurchaseOrder total or the PurchaseOrder
> could calculate the total when required via a method.
>
> I think the easiest way would be to add a method that calculates the total:
>
> @property
> def subtotal(self):
> order_total = 0
> for item in self.purchaseorderitem_set.all():
> order_total += item.qty * item.unit_price
> return order_total
>
> Now it is a property on the purchase order. So calling:
> purchase_order.subtotal will get the total for the purchase order.
>
> 2 other things:
> 1. You can remove the amount in the PurchaseOrderItem and calculate the
> total for the row when required (see my example above) - this of course
> depends on WHEN you want to show the total. The same thing goes for
> calculating the total on the PurchaseOrder. You could add a property the
> same way I did for the PurchaseOrder in the PurchaseOrderItem class.
> 2. The names you have given your properties that are foreign keys are not
> that good from an object oriented perspective. I would for example call the
> invoice_number field on the PurchaseOrder as "invoice". The same goes for
> the po_number_fk fields. Because when you assign them or when you want to
> get a value from the invoice it would be easier to read -
> purchase_order.invoice.id than purchase_order.invoice_number.id.
>
> Hope that helps somewhat.
>
> If you don't want to calculate the total each time (it all depends on the
> usage), you can use signals to see when a model is saved/created and then
> update the subtotal in the PurchaseOrder. See here for information about
> signals: https://docs.djangoproject.com/en/2.0/topics/signals/
>
> Andréas
>
> 2018-08-02 19:27 GMT+02:00 Alexander Joseph <alexander...@gmail.com
> <javascript:>>:
>
>> I've been working on a Purchase Order app but I'm getting a little
>> confused how I'm going to put it all together.
>>
>> I have 3 models -
>>
>> class PurchaseOrder(models.Model):
>> po_number = models.IntegerField(default=get_po_number, unique=True)
>> po_date = models.DateField()
>> invoice_number = models.ForeignKey(Invoice, on_delete=models.CASCADE)
>> ....
>>
>>
>> class PurchaseOrderItem(models.Model):
>> po_number_fk = models.ForeignKey(PurchaseOrder,
>> on_delete=models.CASCADE)
>> qty = models.IntegerField()
>> unit = models.CharField(max_length=100, blank=True, null=True)
>> description = models.CharField(max_length=255)
>> unit_price = models.DecimalField(max_digits=6, decimal_places=2)
>> amount = models.DecimalField(max_digits=6, decimal_places=2)
>>
>>
>> class PurchaseOrderTotal(models.Model):
>> po_number_fk = models.ForeignKey(PurchaseOrder,
>> on_delete=models.CASCADE)
>> subtotal = models.DecimalField(max_digits=6, decimal_places=2)
>> tax = models.DecimalField(max_digits=6, decimal_places=2,
>> default="7.82")
>> shipping = models.DecimalField(max_digits=6, decimal_places=2)
>> other = models.DecimalField(max_digits=6, decimal_places=2)
>> total = models.DecimalField(max_digits=6, decimal_places=2)
>>
>>
>> the first (PurchaseOrder) holds information about the purchase order
>> itself. ie. what the invoice number is, the vendor, etc.
>> the second (PurchaseOrderItem) lists items in the purchase order to
>> purchase
>> the third (PurchaseOrderTotal) totals up the amounts from the items and
>> adds tax etc. (I may not need this model.. I can probably put this info in
>> the first model?)
>>
>>
>> Does it look like I'm going about this in the right way or should I take
>> away the third model and put those fields from the third model into the
>> first model? How do I total up all prices for all items? I'm sure I'll need
>> to do some sort of loop to total up all prices but where do I do that? In
>> the form_valid fucntion? or do I override the save function and do it
>> there? Thanks!
>>
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