konova/api/views/views.py

"""
Author: Michel Peltriaux
Organization: Struktur- und Genehmigungsdirektion Nord, Rhineland-Palatinate, Germany
Contact: michel.peltriaux@sgdnord.rlp.de
Created on: 21.01.22

"""
from abc import abstractmethod

from django.http import JsonResponse
from django.views import View

from api.models import APIUserToken
from api.settings import KSP_TOKEN_HEADER_IDENTIFIER


class AbstractModelAPIView(View):
    """ Base class for API views

    The API must follow the GeoJSON Specification RFC 7946
    https://geojson.org/
    https://datatracker.ietf.org/doc/html/rfc7946

    """
    model = None
    user = None
    lookup = None

    class Meta:
        abstract = True

    def __init__(self, *args, **kwargs):
        self.lookup = {
            "id": None,  # must be set in subclasses
            "deleted__isnull": True,
            "users__in": [],  # must be set in subclasses
        }
        super().__init__(*args, **kwargs)

    @abstractmethod
    def model_to_json(self, entry):
        """ Defines the returned json values of the model

        Args:
            entry (): The found entry from the database

        Returns:

        """
        raise NotImplementedError("Must be implemented in subclasses")

    def fetch_and_serialize(self):
        """ Serializes the model entry according to the given lookup data

        Args:

        Returns:
            serialized_data (dict)
        """
        qs = self.model.objects.filter(**self.lookup)
        serialized_data = {}
        for entry in qs:
            serialized_data[str(entry.pk)] = self.model_to_json(entry)
        return serialized_data

    def dispatch(self, request, *args, **kwargs):
        try:
            self.user = APIUserToken.get_user_from_token(request.headers.get(KSP_TOKEN_HEADER_IDENTIFIER, None))
        except PermissionError as e:
            return JsonResponse(
                {
                    "error": e.__str__()
                },
                status=403
            )
        return super().dispatch(request, *args, **kwargs)