models.py

from django.db import models
from django.contrib.auth.models import User

class Book(models.Model):
    isbn = models.CharField(max_length = 40)
    title = models.CharField(max_length = 100)
    publish_date = models.DateTimeField()
    pages_number = models.IntegerField()
    summary = models.CharField(max_length = 2000)
    edition = models.IntegerField()

    author = models.ForeignKey(Author)
    literaryGenre = models.ForeignKey(LiteraryGenre)
    def __unicode__(self):
        return self.name + " - " + self.author

class Author(models.Model):
    name = models.CharField(max_length = 50)
    def __unicode__(self):
        return self.name

class Valoration(models.Model):
    qualification = models.IntegerField()
    book = models.ForeignKey(Book)
    video = models.ForeignKey(VideoReview)
    user = models.ForeignKey(User)
    def __unicode__(self):
        return self.qualification

class LiteraryGenre(models.Model):
    theme = models.CharField(max_length = 50)
    def __unicode__(self):
        return self.theme

class VideoReview(models.Model):
    url = models.CharField(max_length = 200)