In Django, null=True
and blank=True
are two different options that you can use when defining fields in a model to control how the database stores and validates data.
-
null=True
:- Applies at the database level.
- Specifies whether the database should allow the field to have a
NULL
(empty) value. - It is relevant for database columns and determines whether the field can be stored as
NULL
in the database. - Use it for fields that can legitimately hold empty values, like text fields, dates, and numbers.
- It is not applicable to non-database-backed fields like
ManyToManyField
.
-
blank=True
:- Applies at the validation level.
- Specifies whether the field is allowed to be left blank in forms.
- It is relevant for form validation and determines whether a field is required when a user submits a form.
- Use it for fields that are optional from a user’s perspective, like optional text inputs or optional parts of a form.
- It is not applicable to fields that aren’t used in forms.
Here’s a summary of the differences between null=True
and blank=True
:
- If you want to allow an empty value (NULL) at the database level, use
null=True
. - If you want to allow an empty value (blank) at the validation level (form level), use
blank=True
.
For example, let’s say you have a Django model with a CharField
named title
. Here’s how you might use null=True
and blank=True
:
from django.db import models class Article(models.Model): title = models.CharField(max_length=100, null=True, blank=True)
In this case, null=True
allows the title
field to have NULL values in the database, and blank=True
allows the field to be left blank in forms. This means that both the database column and form field can have empty values without causing issues.