Django TIMESTAMP Field

I'm using django with a legacy mysql db which uses TIMESTAMP columns. Django's inspectdb recognize those fields as int fields. This caused troubles if you want to render its value into a readable date. I googled and found this solution:

http://ianrolfe.livejournal.com/36017.html

from django.db import models
from datetime import datetime
from time import strftime
#
# Custom field types in here.
#
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):
        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):
        return datetime.from_timestamp(value)
    
    def get_db_prep_value(self, value):
        if value==None:
            return None
        return strftime('%Y%m%d%H%M%S',value.timetuple())

 

It worked, until I started to use lookups on these UnixTimestampField fields(such as __gte, __lte, etc). Django will raise a TypeError if I you do .filter(somefield__lte=datetime.now()).

I made some changes to the original code, and finally the lookups works as well:

 

from datetime import datetime
from time import strftime,mktime
#
# Custom field types in here.
#
class UnixTimestampField(models.DateTimeField):
    """UnixTimestampField: creates a DateTimeField that is represented on the
    database as a TIMESTAMP field rather than the usual DATETIME field.
    """
    __metaclass__ = models.SubfieldBase

    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):
        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):
        return datetime.fromtimestamp(value)

    def get_prep_value(self, value):
        if value==None:
            return None
        return mktime(value.timetuple())

    def get_db_prep_value(self, value):
        if value==None:
            return None
        return value