What is the default value of django's model field options ``blank`` and ``null`` when they're not set?

Question

In the documentation, I was not able to find an answer to this.

If I want a field to be left blank, do I have to explicitly set blank=True ?

EDIT: I'm blind. Or stupid. Thanks for pointing that out to me ;)

Answer 1

I know you've linked the docs, but I'm putting this out explicitly for anyone that comes across the same question. The answer to your headline question is explicitly and clearly there in the docs, though - both are False by default. If you want the field to be blank=True, then yes, you'll need to manually specify on every field.

Blank is for Forms:

If True, the field is allowed to be blank. Default is False.

Note that this is different than null. null is purely database-related, whereas blank is validation-related. If a field has blank=True, form validation will allow entry of an empty value. If a field has blank=False, the field will be required.

Null is what is stored the Database if you save a record with nothing in that field. Again, the field attribute for this is null=False

If True, Django will store empty values as NULL in the database. Default is False.

Avoid using null on string-based fields such as CharField and TextField because empty string values will always be stored as empty strings, not as NULL. If a string-based field has null=True, that means it has two possible values for “no data”: NULL, and the empty string. In most cases, it’s redundant to have two possible values for “no data;” the Django convention is to use the empty string, not NULL.

For both string-based and non-string-based fields, you will also need to set blank=True if you wish to permit empty values in forms, as the null parameter only affects database storage (see blank).

There are plenty of occasions when you'd want the form to be blank, but the database entry to be not Null - if for example, you were specifying your own custom slug on model save.

This also means, of course, that any custom Fields you derive from the main Field class will have the same default behaviour. If that really bothers you, you could override the Field class with your desired behaviour, but that would be really janky to debug for the others who come after you.