class Test1(models.Model):
    arg1 = models.CharField(max_length=50)
    arg2 = models.CharField(max_length=50)

    def __str__(self):
        return self.arg1

class Test2(models.Model):
    coup = models.ForeignKey(Test1, on_delete=models.CASCADE)
    date = models.CharField(max_length=20, default=None)

    def __str__(self):
        return self.coup.arg1