How to Refer a Parent table's key instead of the complete object instance in Django

I have just started working on Django, angularjs , The issue currently i am facing is I have created a model in django as following

**class Car_Booking(models.Model):
    owner = models.ForeignKey('auth.User', related_name='booking_user')
   car_id=models.IntegerField(max_length=4,default=1)
    extra_field1=models.CharField(max_length=100,null=True)
    extra_field2=models.CharField(max_length=50,null=True)
    extra_field3=models.CharField(max_length=50,null=True)**  

The Serializer is as following

**class CarBookingSerializer(serializers.HyperlinkedModelSerializer):
    owner = serializers.ReadOnlyField(source='owner.username')
    class Meta:
        model = Car_Booking
        fields = ('car_id','owner','extra_field1','extra_field2','extra_field3')**

And view is as following

**class CarBookingViewSet(viewsets.ModelViewSet):
    """
    This viewset automatically provides `list`, `create`, `retrieve`,
    `update` and `destroy` actions.
    Additionally we also provide an extra `highlight` action.
    """
    queryset = Car_Booking.objects.all()
    serializer_class = CarBookingSerializer
    permission_classes = (permissions.AllowAny,

    def perform_create(self, serializer):
            serializer.save(owner=self.request.user)**

Now i developed a front end on Angularjs, the templelates i built were on the same server say localhost:8000 so when i call the view to insert the data by passing car_id, extra_field1, extra_field2 and extra_field 3 it gets saved successfully because i already get logged in and saved the user information into the cookies so i guess the Owner field is resolved automatically. Now when i call the same view from the IONIC framework on server localhost:5000(port is differnt) it give me the error, "Owner must be a user instance". I have searched a lot but can not find how to send the user authentication information, or save it accross the domains. Secondly i have tried to pass the owner_id but when i write the owner_id into the serializer it says "Owner_id is not a valid modlebase" but while calling throught the command prompt i can set the owner_id, Any Help on the following questions

***1. How can i send the username and password along the Post URL

  1. How can i set the owner_id instead of OWNER object instance.***

Regards