blank=True vs null=True in Django

• null=True

  • Database layer.
  • Column accepts SQL NULL.
  • Django represents the absence of a value as Python None.
  • Needed for non-string fields (e.g., DateField, ForeignKey) to store "no value."
  • Indexes and unique constraints treat NULL as distinct from every non-null value.

• blank=True

  • Validation layer.
  • Model and form validation permit an empty value on save or submit.
  • For strings, the actual value stored is '' (empty string) unless null=True is also set.
  • Has no effect on the SQL schema.

• Common patterns

  • String fields: blank=True, null=False → empty string stored, forms omit value.
  • Non-string fields: blank=True, null=True → database NULL used, validation allows omission.
  • Mixing null=True, blank=False rarely useful—database allows NULL, but validation rejects empty input.
  • Leaving both as False enforces mandatory data at both database and validation levels.

• Key distinctions

  • null controls storage; blank controls validation.
  • Database NULL ≠ empty string; choose one to avoid ambiguity.