new_contents: # file: netdevice/serializers.py
  
  from rest_framework import serializers
  from .models import logical_interface, interface, router, network_os
  
  
  class LogicalInterfaceSerializer(serializers.ModelSerializer):
      class Meta:
          model = logical_interface
          fields = ('__all__')
  
  class InterfaceSerializer(serializers.ModelSerializer):
      class Meta:
          model = interface
          fields = ('__all__')
  
  class RouterSerializer(serializers.ModelSerializer):
      class Meta:
          model = router
          fields = ('__all__')
  
  class NetworkOsSerializer(serializers.ModelSerializer):
      class Meta:
          model = network_os
          fields = ('__all__')
  
subject: Add netdevice/serializers.py file, and serializers for all objects.