modals.py

class Server(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    name = models.CharField(max_length=20, null=True)
    hostname = models.CharField(max_length=50, null=True, blank=True)
    ip = models.GenericIPAddressField()
    ip2 = models.GenericIPAddressField(null=True, blank=True)
    user_name = models.CharField(max_length=20, null=True)
    password = models.CharField(max_length=200, null=True, blank=True)
    ssh_key = models.FileField(null=True, blank=True)
    status = models.CharField(max_length=10, null=True, blank=True)
    last_login_time = models.DateTimeField(null=True, blank=True)
    last_login_from = models.GenericIPAddressField(null=True, blank=True)

    def __str__(self):
        return str(self.user) + " - " + self.name

class InventoryGroups(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    name = models.CharField(max_length=20, null=True)
    host = models.ManyToManyField(Server)
    description = models.CharField(max_length=100, null=True, blank=True)

    def get_hosts(self):
        if self.host:
            hostlist = []
            for name in self.host.all():
                hostlist.append(name)
            return hostlist

    def __str__(self):
        return str(self.user) + " - " + self.name