PTC-W0906 · Field allows null but not blank

Field allows null but not blank PTC-W0906

Anti-pattern

Major

a year ago — a year old

Missing blank kwarg (defaults to False) will allow field to be null but not blank

 9# Create your models here.
10class Groups(models.Model):
11    user = models.ForeignKey(NewUserResgistration, on_delete=models.CASCADE, null=True)
12    name = models.CharField(max_length=200, null=True)13
14    def __str__(self):
15        return self.name

Missing blank kwarg (defaults to False) will allow field to be null but not blank

mailer/models.py

18class GroupDetails(models.Model):
19    GENDER = (("Male", "Male"), ("Female", "Female"), ("Others", "Others"))
20    group = models.ForeignKey(Groups, on_delete=models.CASCADE, null=True)
21    email = models.CharField(max_length=200, null=True)22    name = models.CharField(max_length=200, null=True)
23    gender = models.CharField(max_length=200, choices=GENDER, blank=False, null=True)
24

Missing blank kwarg (defaults to False) will allow field to be null but not blank

mailer/models.py

19    GENDER = (("Male", "Male"), ("Female", "Female"), ("Others", "Others"))
20    group = models.ForeignKey(Groups, on_delete=models.CASCADE, null=True)
21    email = models.CharField(max_length=200, null=True)
22    name = models.CharField(max_length=200, null=True)23    gender = models.CharField(max_length=200, choices=GENDER, blank=False, null=True)
24
25    def __str__(self):

Field allows null but not blank values

mailer/models.py

20    group = models.ForeignKey(Groups, on_delete=models.CASCADE, null=True)
21    email = models.CharField(max_length=200, null=True)
22    name = models.CharField(max_length=200, null=True)
23    gender = models.CharField(max_length=200, choices=GENDER, blank=False, null=True)24
25    def __str__(self):
26        return str(self.name) + "-" + str(self.email)

Description

If null is True and blank is False then Django and the database disagree on whether empty values are allowed.

The null attribute specifies that the database will accept it if no value is passed to the field. The blank attribute specifies Django should not check if the value is present when Model.clean is called.

If Model.save is called via the shell without first calling Model.clean: the bad data will be saved and there may be unwanted side effects, such as:

Complex ORM queries
Validation error if the records are validated the next time
Inconsistent datatypes

These unwanted side effects can cause more serious problems that are hard to debug long after the original error occurred.

Not preferred:

class Feedback(models.Model):
    created = models.DateField(null=True)
    updated = models.DateField(null=True, blank=False)

Preferred:

class Feedback(models.Model):
    created = models.DateField(null=True, blank=True)
    updated = models.DateField(null=True, blank=True)

Bulkmailer / BulkMailer-Backend

Not preferred:

Preferred: