class Book(models.Model):
    title = models.CharField(max_length=200)
    author = models.CharField(max_length=100)
    date = models.CharField(max_length=20)
    pages = models.CharField(max_length=5)
    img = models.TextField()
    desc = models.TextField()
    full_text = models.TextField()

    def save(self, *args, **kwargs):
        self.full_text = ''.join(self.full_text.split('\n'))
        self.pages = str(math.ceil(len(self.full_text.split(' ')) / 20))
        super(Book, self).save(*args, **kwargs)