mirror of
https://github.com/django/django.git
synced 2024-12-28 03:55:50 +00:00
02fcfe6216
git-svn-id: http://code.djangoproject.com/svn/django/trunk@3031 bcc190cf-cafb-0310-a4f2-bffc1f526a37
52 lines
1.2 KiB
Python
52 lines
1.2 KiB
Python
"""
|
|
31. Callable defaults
|
|
|
|
You can pass callable objects as the ``default`` parameter to a field. When
|
|
the object is created without an explicit value passed in, Django will call
|
|
the method to determine the default value.
|
|
|
|
This example uses ``datetime.datetime.now`` as the default for the ``pub_date``
|
|
field.
|
|
"""
|
|
|
|
from django.db import models
|
|
from datetime import datetime
|
|
|
|
class Article(models.Model):
|
|
headline = models.CharField(maxlength=100, default='Default headline')
|
|
pub_date = models.DateTimeField(default=datetime.now)
|
|
|
|
def __str__(self):
|
|
return self.headline
|
|
|
|
API_TESTS = """
|
|
>>> from datetime import datetime
|
|
|
|
# No articles are in the system yet.
|
|
>>> Article.objects.all()
|
|
[]
|
|
|
|
# Create an Article.
|
|
>>> a = Article(id=None)
|
|
|
|
# Grab the current datetime it should be very close to the default that just
|
|
# got saved as a.pub_date
|
|
>>> now = datetime.now()
|
|
|
|
# Save it into the database. You have to call save() explicitly.
|
|
>>> a.save()
|
|
|
|
# Now it has an ID. Note it's a long integer, as designated by the trailing "L".
|
|
>>> a.id
|
|
1L
|
|
|
|
# Access database columns via Python attributes.
|
|
>>> a.headline
|
|
'Default headline'
|
|
|
|
# make sure the two dates are sufficiently close
|
|
>>> d = now - a.pub_date
|
|
>>> d.seconds < 5
|
|
True
|
|
"""
|