Django custom field validator vs. clean

I would like to create TodayOrLaterDateField() which would subclass DateField() field as I am using this condition in many places. The purpose of this field would be avoiding putting dates from the past.

开发者_如何学运维What is the most straightway way of doing this? I am confused with validator vs. clean method. I've tried with clean() but when comparing value to datetime.date.today() I am getting "compare unicode object to date" error.

I'm using Django 1.3

Validators only validate, they don't return the improved format; Clean methods both validate and return a (sometimes amended) value.

I think the way to go here is to just use a DateField with a validator as a inherited class of DateField with a default_validators set.

import datetime
from django.core import exceptions
from django.db import models
from django.utils.translation import ugettext_lazy as _

def validate_date_today_or_later(value):
    'Place this in validators.py and import it to keep your model a bit cleaner'
    if value < datetime.date.today():
        raise exceptions.ValidationError(_('Date must be today or later'))

class TodayOrLaterDateField(models.DateField):
    default_validators = [validate_date_today_or_later,]

edit: You can apply the same validator to your form fields as well if you just want it there and not in your whole app.

You can extend models.DateField and override to_python method. Didn't tested on Django 1.3 but should work.

import datetime
from django.core import exceptions
from django.db import models

class TodayOrLaterDateField(models.DateField):
    def to_python(self, value):
        value = super(TodayOrLaterDateField, self).to_python(value)
        if value < datetime.date.today():
            raise exceptions.ValidationError(u'Date must be today or later')
        return value