"""

32. 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

__test__ = {'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

"""}