django：TypeError：'tuple'对象不可调用

获取类型错误时，"tuple"对象不可调用.知道会是什么吗？(不要担心缩进.它会以奇怪的方式复制.)我试图根据StoreLiquis的包装大小来做出 Select .

Views.py:

def storeliquor(request, store_id, liquor_id):        
a = StoreLiquor.objects.get(StoreLiquorID=liquor_id)
s = Store.objects.get(StoreID=store_id)
x = Order.objects.get(storeID=s, Active=True)
y = a.OffPremisePrice
c = a.BottleSize

g = request.POST.get('OrderAmount', '')
b = a.PackSize
h = b*2
d = b*3
e = b*4
r = b*5
if c == "1750 ML":
    pack_size = (
        ('1', '1')
        ('3', '3')
        (b, b)
        (h, h)
        (d, d)
        (e, e)
        (r, r)
    )
elif c == "1000 ML":
    pack_size = (
        ('1', '1')
        ('3', '3')
        ('6', '6')
        (b, b)
        (h, h)
        (d, d)
        (e, e)
        (r, r)
    )
elif c == "750 ML":
    pack_size = (
        ('1', '1')
        ('3', '3')
        ('6', '6')
        (b, b)
        (h, h)
        (c, d)
        (e, e)
        (r, r)
    )     
elif c == "375 ML":
    pack_size = (
        ('3', '3')
        ('6', '6')
        ('12', '12')
        (b, b)
        (h, h)
        (d, d)
        (e, e)
        (r, r)
    )        
elif c == "200 ML":
    pack_size = (
        ('12', '24')
        ('24', '24')
        (b, b)
        (c, c)
        (c, d)
        (e, e)
        (r, r)
    ) 
else:
    pack_size = (
        (b, b)
        (c, c)
        (c, d)
        (e, e)
        (r, r)
    )        




if request.method == "POST":
    f = AddToOrderForm(request.POST)

    if f.is_valid():
        z = f.save(commit=False)
        z.TotalPrice = (float(y)) * (float(g))
        z.storeliquorID = a
        z.orderID = x

        z.save()        

    return HttpResponseRedirect('/stores/get/%s' % store_id)

else:
    f = AddToOrderForm()
    f.fields['OrderAmount'].choices = pack_size      
args = {}


args['liquor'] = a
args['s'] = s
args['form'] = f   

return render(request,'storeliquor.html', args)

模型文件:

class LiquorOrder(models.Model):

LiquorOrderID = models.AutoField(primary_key=True)
storeliquorID = models.ForeignKey(StoreLiquor)
orderID = models.ForeignKey(Order)
OrderAmount = models.CharField('Order Amount', max_length=3)
TotalPrice = models.DecimalField('Total Price', max_digits=5, decimal_places=2)
StorePrice = models.DecimalField('Store Price', max_digits=5, decimal_places=2)

表格文件:

class AddToOrderForm(forms.ModelForm):

class Meta:
    model = LiquorOrder
    fields = ('OrderAmount', 'StorePrice')