Fixed #8802 -- Documented MySQL's usage of 1/0 instead of True/False for model

BooleanFields.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8910 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2008-09-03 06:14:13 +00:00
parent fd78e89d1e
commit fd1d986bb1
2 changed files with 23 additions and 0 deletions

View File

@ -228,6 +228,16 @@ storage engine, you have a couple of options.
.. _AlterModelOnSyncDB: http://code.djangoproject.com/wiki/AlterModelOnSyncDB
Boolean fields in Django
-------------------------
Since MySQL doesn't have a direct ``BOOLEAN`` column type, Django uses a
``TINYINT`` column with values of ``1`` and ``0`` to store values for the
:class:`~django.db.models.BooleanField` model field. Refer to the documentation
of that field for more details, but usually this won't be something that will
matter unless you're printing out the field values and are expecting to see
``True`` and ``False.``.
.. _oracle-notes:

View File

@ -296,6 +296,19 @@ A true/false field.
The admin represents this as a checkbox.
.. admonition:: MySQL users..
A boolean field in MySQL is stored as a ``TINYINT`` column with a value of
either 0 or 1 (most databases have a proper ``BOOLEAN`` type instead). So,
for MySQL, only, when a ``BooleanField`` is retrieved from the database
and stored on a model attribute, it will have the values 1 or 0, rather
than ``True`` or ``False``. Normally, this shouldn't be a problem, since
Python guarantees that ``1 == True`` and ``0 == False`` are both true.
Just be careful if you're writing something like ``obj is True`` when
``obj`` is a value from a boolean attribute on a model. If that model was
constructed using the ``mysql`` backend, the "``is``" test will fail.
Prefer an equality test (using "``==``") in cases like this.
``CharField``
-------------