TypeError with calculated field
unsupported operand type(s) for *: 'int' and 'NoneType'
error in the return line below
models.py
def get_subtotal(self):
return self.price_sale * self.quantity
subtotal = property(get_subtotal)
admin.py
class SaleDetailInline(admin.TabularInline):
list_display = ['product', 'quantity', 'price_sale', 'subtotal']
readonly_fields = ['subtotal', ]
model = SaleDetail
extra = 0
In the view the subtotal works, but not in Admin.
This error is occurring because you are trying to multiply an integer by an empty type.
Example:
>>> price_sale = None
>>> quantity = 2
>>> print price_sale * quantity
Traceback (most recent call last):
File "<input>", line 1, in <module>
TypeError: unsupported operand type(s) for *: 'int' and 'NoneType'
You can correct it this way:
def get_subtotal(self):
try:
return self.price_sale * self.quantity
except TypeError:
return 0
or:
def get_subtotal(self):
if self.price_sale and self.quantity:
return self.price_sale * self.quantity
else:
return 0