Re: Negative Stock Prevention

I don't see any error. Did you forget to post it?

On August 31, 2022 5:57:32 AM CDT, tech george <techgeorge4@gmail.com> wrote:

Hello,

Sorry for the late reply.

I changed the models as below and added checkConstraint , But when I migrate I get the below error.

What am I still doing wrong?

class Stock(models.Model):
    quantity = models.PositiveIntegerField(default='0', blank=True, null=True)
    reorder_level = models.PositiveIntegerField(default='0', blank=True, null=True)

class Meta:
        CheckConstraint(check=Q(quantity__gt=0), name='quantity')

On Tue, Aug 30, 2022 at 6:09 PM Thomas Couch <t.couch@ucl.ac.uk> wrote:

I don't see where you define the quantity variable, should that be instance.quantity? Also, presumably you want to check if quantity is greater than or equal to qu rather than 0.

Try changing `if quantity > 0` to `if instance.quantity >= qu`

On Tuesday, August 30, 2022 at 3:44:51 PM UTC+1 Ryan Nowakowski wrote:

On Mon, Aug 29, 2022 at 05:18:39PM +0300, tech george wrote:
> Please help crack the below code, I want to prevent negative stock, and if
> the stock is == 0, deduct it from reorder_level instead.
> Currently, the stock goes negative.
>
> models.py
>
> class Stock(models.Model):
> quantity = models.IntegerField(default='0', blank=True, null=True)
> reorder_level = models.IntegerField(default='0', blank=True, null=True)
>
> class Dispense(models.Model):
> drug_id = models.ForeignKey(Stock,
> on_delete=models.SET_NULL,null=True,blank=False)
> dispense_quantity = models.PositiveIntegerField(default='1',
> blank=False, null=True)
> taken=models.CharField(max_length=300,null=True, blank=True)

Maybe change quantity and reorder_level to PositiveIntegerField?

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