Question

I have a MySQL database, right now I’m generating all of the datetime fields as models.DateTimeField. Is there a way to get a timestamp instead? I want to be able to autoupdate on create and update etc.

The documentation on django doesn’t have this?

Answer 1

There was actually a very good and informative article on this. Here:
http://ianrolfe.livejournal.com/36017.html

The solution on the page is slightly deprecated, so I did the following:

from django.db import models
from datetime import datetime
from time import strftime

class UnixTimestampField(models.DateTimeField):
    """UnixTimestampField: creates a DateTimeField that is represented on the
    database as a TIMESTAMP field rather than the usual DATETIME field.
    """
    def __init__(self, null=False, blank=False, **kwargs):
        super(UnixTimestampField, self).__init__(**kwargs)
        # default for TIMESTAMP is NOT NULL unlike most fields, so we have to
        # cheat a little:
        self.blank, self.isnull = blank, null
        self.null = True # To prevent the framework from shoving in "not null".

    def db_type(self, connection):
        typ=['TIMESTAMP']
        # See above!
        if self.isnull:
            typ += ['NULL']
        if self.auto_created:
            typ += ['default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP']
        return ' '.join(typ)

    def to_python(self, value):
        if isinstance(value, int):
            return datetime.fromtimestamp(value)
        else:
            return models.DateTimeField.to_python(self, value)

    def get_db_prep_value(self, value, connection, prepared=False):
        if value==None:
            return None
        # Use '%Y%m%d%H%M%S' for MySQL < 4.1
        return strftime('%Y-%m-%d %H:%M:%S',value.timetuple())

To use it, all you have to do is:
timestamp = UnixTimestampField(auto_created=True)

In MySQL, the column should appear as:
'timestamp' timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,

Only drawback with this is that it only works on MySQL databases. But you can easily modify it for others.