import os

from django.db import models

from django.core.exceptions import ValidationError

class Person(models.Model):

    name = models.CharField(max_length=100)

class Triple(models.Model):

    left = models.IntegerField()

    middle = models.IntegerField()

    right = models.IntegerField()

    class Meta:

        unique_together = (('left', 'middle'), (u'middle', u'right'))

class FilePathModel(models.Model):

    path = models.FilePathField(path=os.path.dirname(__file__), match=".*\.py$", blank=True)

class Publication(models.Model):

    title = models.CharField(max_length=30)

    date_published = models.DateField()

    def __unicode__(self):

        return self.title

class Article(models.Model):

    headline = models.CharField(max_length=100)

    publications = models.ManyToManyField(Publication)

    def __unicode__(self):

        return self.headline

class CustomFileField(models.FileField):

    def save_form_data(self, instance, data):

        been_here = getattr(self, 'been_saved', False)

        assert not been_here, "save_form_data called more than once"

        setattr(self, 'been_saved', True)

class CustomFF(models.Model):

    f = CustomFileField(upload_to='unused', blank=True)

class RealPerson(models.Model):

    name = models.CharField(max_length=100)

    def clean(self):

        if self.name.lower() == 'anonymous':

            raise ValidationError("Please specify a real name.")

class Author(models.Model):

    publication = models.OneToOneField(Publication, null=True, blank=True)

    full_name = models.CharField(max_length=255)

class Author1(models.Model):

    publication = models.OneToOneField(Publication, null=False)

    full_name = models.CharField(max_length=255)

class Homepage(models.Model):

    url = models.URLField(verify_exists=False)