Hi
I've tried to create a custom Field for the database to store
Timedelta objects. Since I only need exactness to the minute and won't
have any large timedeltas I'm using a simple Integer to store it in
the database. Maybe I'll make this configurable later.
this is the code:
============
from django.db.models.fields import IntegerField, Field
from django.core import validators
import datetime
from contrib.numeric_utilities import timedelta2minutes
class TimedeltaField(IntegerField):
def to_python(self, value):
# turns the integer saved in the database to a python
timedelta object
if value is None:
return value
if isinstance(value, datetime.timedelta):
return value
validators.isInteger(str(value), None)
try:
return datetime.timedelta(minutes=int(value))
except (TypeError, ValueError):
raise validators.ValidationError, u"This value must be an
integer (it gets converted to a Timedelta)"
def get_db_prep_save(self, value):
# Turns the input into a integer of minutes for save in db
if isinstance(value, datetime.timedelta):
value = timedelta2minutes(int(value))
return Field.get_db_prep_save(self, value)
def get_internal_type(self):
return "IntegerField"
=========
timedelta2minutes is a simple function that returns an integer.
On the commandline:
=================
>>> from mytest.models import *;
>>> t = MyTest.objects.all()[0]
>>> t.a_timedelta
2342
>>> type(t.a_timedelta)
<type 'int'>
>>> t.validate()
{}
>>> t.a_timedelta
datetime.timedelta(0, 39960)
>>> type(t.a_timedelta)
<type 'datetime.timedelta'>
==========
So... until I run validate() at least once the field returns the int
from the database instead of the converted value from to_python(). I
ran some tests with print statements in the to_python methods... they
never get called until validate() is run. The same for the built-in
DateField, but there the value still gets magically returned as a
datetime.date object.
Saving works fine... I can assign a timedelta objects to a_timedelta
and save() and the value gets correctly saved to the database as a int.
What am I doing wrong, that the value is only present as a datetime
object once I've done a validate()?
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/django-users?hl=en
-~----------~----~----~----~------~----~------~--~---
