python_2_unicode_com patible class ContactRelation CopyMixin TimeStamp

@python_2_unicode_compatible
class ContactRelation(CopyMixin, TimeStampedModel):
    project = models.ForeignKey('pekama.Project', related_name='contact_relations', null=True, blank=True)

    sub_matter = models.ForeignKey('legal.SubMatter', null=True)
    event = models.ForeignKey('legal.Event', null=True, blank=True, on_delete=models.SET_NULL)

    is_public = models.BooleanField(default=False)

    contact = models.ForeignKey('Contact')
    relation = models.ForeignKey('Relation')

    ownership_percentage = models.IntegerField(null=True, blank=True, validators=[MinValueValidator(0),
                                                                                  MaxValueValidator(100)])

    class Meta:
        unique_together = ('project', 'contact', 'relation')

    def __str__(self):
        return str(self.contact)