String field is nullable PTC-W0901
Anti-pattern
Major
9 months ago
—
9 months old
CharField has been made nullable here, making it inconsistent31 on_delete=models.CASCADE
32 )
33 pgtiou = models.CharField(max_length=255, null=True, blank=True)
34 pgt = models.CharField(max_length=255, null=True, blank=True)35 date = models.DateTimeField(auto_now_add=True)
36
37 @classmethodCharField has been made nullable here, making it inconsistent30 blank=True,
31 on_delete=models.CASCADE
32 )
33 pgtiou = models.CharField(max_length=255, null=True, blank=True)34 pgt = models.CharField(max_length=255, null=True, blank=True)
35 date = models.DateTimeField(auto_now_add=True)
36CharField has been made nullable here, making it inconsistent20class ProxyGrantingTicket(models.Model):
21 class Meta:
22 unique_together = ('session_key', 'user')
23 session_key = models.CharField(24 max_length=SESSION_KEY_MAXLENGTH,
25 blank=True, null=True)
26 user = models.ForeignKey(
Description
The null attribute specifies that the field can be None, or null at database level.
This makes the ORM queries and the Python code more complex because the values will sometime be None and other times, a string.
Hence, you'd need extra code to check on performing string operations on a NoneType.
It is recommended to provide a default='' option to the fields instead.
This way, you wonn't have to worry about null values and the database would also throw an exception if there is an attempt to explicitly save None.
Not Preferred:
class Customer(models.Model):
remarks = models.CharField(null=True)
query = Q(remarks__isnull=True) | Q(remarks='')
for customer in Customer.objects.filter(query):
...
Preferred:
class Customer(models.Model):
remarks = models.CharField(default='')
for customer in Customer.objects.filter(remarks=''):
# customer.remarks is always a str
...