class Issue(models.Model):
    id = models.AutoField(primary_key=True)
    reader = models.ForeignKey(Reader, on_delete=models.CASCADE, verbose_name="Читатель")
    book = models.ManyToManyField(Book, verbose_name="Книги")
    date_start = models.DateField(verbose_name="Дата выдачи")
    date_planned_end = models.DateField(verbose_name="Планируемая дата возврата")
    date_real_end = models.DateField(blank=True, null=True, verbose_name="Фактическая дата возврата")

    def __str__(self):
        return "{0} {2}-{3} ({4}) {1}".format(self.id, self.reader, self.date_start,
                                              self.date_planned_end, self.date_real_end)

    class Meta:
        verbose_name = 'Выдача'
        verbose_name_plural = 'Выдачи'