###################   my_server/r_server/serializer.py
from rest_framework import serializers
from .models import *


class NetAdapterSerializer(serializers.ModelSerializer):
    class Meta:
        model = NetAdapter
        exclude = ['client']


class DisksSerializer(serializers.ModelSerializer):
    class Meta:
        model = Disks
        exclude = ['client']


class ClientSerializer(serializers.ModelSerializer):
    disk = DisksSerializer(many=True)
    adapter = NetAdapterSerializer(many=True)

    def create(self, validated_data):
        disks_data = validated_data.pop('disk')
        net_adapter_data = validated_data.pop('adapter')
        client = Client.objects.create(**validated_data)

        for disk_data in disks_data:
            Disks.objects.create(client=client, **disk_data)

        for adapter_data in net_adapter_data:
            NetAdapter.objects.create(client=client, **adapter_data)

        return client

    def update(self, instance, validated_data): # <---- It's my problem... :(
        disks_data = validated_data.pop('disk')
        net_adapter_data = validated_data.pop('adapter')
        client = Client.objects.update(**validated_data)

        for disk_data in disks_data:
            Disks.objects.update(client=instance, **disk_data)

        for adapter_data in net_adapter_data:
            NetAdapter.objects.update(client=instance, **adapter_data)

        return client

    class Meta:
        model = Client
        fields = '__all__'


###################   my_server/r_server/urls.py
from django.urls import path
from .views import ClientDetailView, ClientViewSet, ClientAddView

urlpatterns = [
    path('clients/', ClientViewSet.as_view()),
    path('clients/<int:pk>', ClientDetailView.as_view()),
    path('clients/add', ClientAddView.as_view()),
]


###################   rebrian_server/r_server/views.py
from rest_framework import generics
from .serializer import ClientSerializer
from .models import Client


class ClientViewSet(generics.ListAPIView):

    queryset = Client.objects.all()
    serializer_class = ClientSerializer


class ClientAddView(generics.CreateAPIView):

    queryset = Client.objects.all()
    serializer_class = ClientSerializer


class ClientDetailView(generics.RetrieveUpdateDestroyAPIView):

    queryset = Client.objects.all()
    serializer_class = ClientSerializer



################################## my_server/r_server/models.py
from django.db import models


class Client(models.Model):
    name = models.CharField('name', max_length=255)
    description = models.TextField('Description', max_length=255, default='no_description')
    memory_total = models.CharField('Memory total', max_length=20)
    cpu_cores = models.IntegerField()
    cpu_physical_cores = models.IntegerField()
    cpu_frequency_current = models.IntegerField()
    cpu_frequency_max = models.IntegerField()
    date_add = models.DateTimeField(auto_now_add=True)
    date_update = models.DateTimeField(auto_now=True)
    client_is_active = models.BooleanField(default=True, verbose_name='Active')

    class Meta:
        managed = True
        verbose_name = 'Client'

    def __str__(self):
        return '%s: %s' % (self.name, self.description)


class Disks(models.Model):
    client = models.ForeignKey('Client', related_name='disk', verbose_name='Disk', on_delete=models.CASCADE)
    device = models.CharField('Device', max_length=10)
    total = models.IntegerField('Total volume')
    used = models.IntegerField('Used space')
    free = models.IntegerField('Free space')
    fstype = models.CharField('FS type', max_length=15)
    mountpoint = models.CharField('Mount point', max_length=5)

    class Meta:
        managed = True
        verbose_name = 'Disk'

    def __str__(self):
        return '%s: %s' % (self.device, self.total)


class NetAdapter(models.Model):
    client = models.ForeignKey('Client', related_name='adapter', verbose_name='NetAdapter',
                               on_delete=models.CASCADE)
    net_adapter_device = models.CharField('NetAdapter Name', max_length=200)
    net_adapter_status = models.BooleanField(default=False)
    net_adapter_mtu = models.IntegerField()
    net_adapter_speed = models.IntegerField()
    net_adapter_duplex = models.CharField(default='Unknown', max_length=200)
    IPv4 = models.GenericIPAddressField('IPv4', protocol='IPv4', default='0.0.0.0')
    MAC = models.CharField(default='00-00-00-00-00-00', max_length=17)

    class Meta:
        managed = True
        verbose_name = 'NetAdapter'

    def __str__(self):
        return '%s: %s' % (self.net_adapter_device, self.IPv4)