Figuring out Django class-based validators

django-class-based-val.py

from django.db import models
from django.core.exceptions import ValidationError
from django.utils.translation import ugettext_lazy as _, ungettext_lazy
from django.core.validators import MaxValueValidator, MinValueValidator
from django.utils.deconstruct import deconstructible


@deconstructible
class MaxWordValidator(object):
    print "MaxWordValidator"
    compare = lambda self, a, b: a > b
    clean = lambda self, x: len(x)
    message = ungettext_lazy(
        'Ensure this value has at least %(limit_value)d word (it has %(show_value)d).',
        'Ensure this value has at least %(limit_value)d words (it has %(show_value)d).',
        'limit_value')
    code = 'max_word_length'

    def __init__(self, limit_value, message=None):
        print "limit_value"
        print limit_value
        self.limit_value = limit_value
        if message:
            self.message = message

    def __call__(self, value):
        print value
        cleaned = self.clean(value)
        params = {'limit_value': self.limit_value, 'show_value': cleaned, 'value': value}
        print params
        if self.compare(cleaned, self.limit_value):
            raise ValidationError(self.message, code=self.code, params=params)

    def __eq__(self, other):
        return (
            isinstance(other, self.__class__)
            and (self.limit_value == other.limit_value)
            and (self.message == other.message)
            and (self.code == other.code)
        )


class MaxWordCharField(models.CharField):
    default_validators = [MaxWordValidator(5)]


class TryModel(models.Model):
    name = models.CharField(max_length=32)
    intmax_field = models.IntegerField(default=10, validators=[MaxValueValidator(14)])
    nextmax_field = models.IntegerField(default=21, validators=[MaxValueValidator(14)])
    myfloat = models.FloatField(validators=[MinValueValidator(-100.00), MaxValueValidator(1000.00)])
    maxword = MaxWordCharField(default="", max_length=150)
    newmaxword = models.CharField(default="", max_length=150, validators=[MaxWordValidator(5)])