For future reference - I had to change my function to
def get_po_number():
last_po = PurchaseOrder.objects.order_by('po_number').last()
if last_po:
last_po_num = last_po.po_number
new_po_num = last_po_num + 1
else:
new_po_num = '1'
po_number = new_po_num
return po_number
class PurchaseOrder(models.Model):
po_number = models.IntegerField(unique=True, default=get_po_number)
And the default value should be set to get_po_number
On Mon, Jul 23, 2018, 10:33 PM mottaz hejaze <[email protected]> wrote:
> you can use count() in views or models to count number of objects then add
> the new record
>
> On Tue, 24 Jul 2018, 02:55 Alexander Joseph, <[email protected]>
> wrote:
>
>> Thanks Michael and Gerald. With an auto key field or primary key field
>> would users still be able to input their own value? And if so how would I
>> be able to give it a default attribute in a form that shows what the next
>> number should be, if the user decides to choose to use the auto increment?
>> Thanks again
>>
>> On Mon, Jul 23, 2018, 6:36 PM Gerald Brown <[email protected]> wrote:
>>
>>> From
>>> "https://docs.djangoproject.com/en/2.0/topics/db/models/#automatic-primary-key-fields";
>>> <https://docs.djangoproject.com/en/2.0/topics/db/models/#automatic-primary-key-fields>,
>>> it has a further definition of automatic primary key fields. In your model
>>> just add "(primary_key=True)" to po_number field.
>>>
>>> On Tuesday, 24 July, 2018 07:54 AM, Michael MacIntosh wrote:
>>>
>>> Hi,
>>>
>>> Aren't you looking for the AutoField?
>>>
>>> https://docs.djangoproject.com/en/2.0/ref/models/fields/#autofield
>>>
>>> It will automatically increment based on each record added to the table.
>>>
>>>
>>> As an aside, the problem you are having is that in python, the first
>>> argument to a class is a reference to the instance of that class. In C
>>> this is often called a context. In C++ and Java it would be like the
>>> `this` pointer. So you wouldn't generally pass "self" to a class member.
>>>
>>> Hope that helps!
>>>
>>> On 7/23/2018 1:39 PM, Alexander Joseph wrote:
>>>
>>> Hello,
>>>
>>> I have a model ...
>>>
>>> class PurchaseOrder(models.Model):
>>> po_number = models.IntegerField(unique=True)
>>>
>>>
>>> and a function ...
>>>
>>> def get_po_number(self, *args, **kwargs):
>>> if not self.id:
>>> last_po = PurchaseOrder.objects.order_by('po_number').last()
>>> if last_po:
>>> last_po_num = last_po.po_number[-2:]
>>> new_po_num = int(last_po_num) + 1
>>> else:
>>> new_po_num = '0001'
>>> self.po_number = new_po_num
>>> return self.po_number
>>>
>>>
>>> what I'm trying to do is use the get_po_number() function to get a
>>> default value for the po_number field in the model. However when I set the
>>> default in the model like so...
>>>
>>> class PurchaseOrder(models.Model):
>>> po_number = models.IntegerField(unique=True,
>>> default=get_po_number(self))
>>>
>>> it says "NameError: name 'self' is not defined"
>>>
>>>
>>> What am I doing wrong? Thanks!
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