code: def create(self, request):
          
          if self.readonly:
              return HTTPMethodNotAllowed(headers={'Allow': 'GET, HEAD'})
          collection = loads(request.body, object_hook=GeoJSON.to_instance)
          if not isinstance(collection, FeatureCollection):
              return HTTPBadRequest()
          session = self.Session()
          objects = []
          for feature in collection.features:
              create = False
              obj = None
              if hasattr(feature, 'id') and feature.id is not None:
                  obj = session.query(self.mapped_class).get(feature.id)
              if self.before_create is not None:
                  self.before_create(request, feature, obj)
              if obj is None:
                  obj = self.mapped_class(feature)
                  create = True
              else:
                  obj.__update__(feature)
              if create:
                  session.add(obj)
              objects.append(obj)
          session.flush()
          collection = FeatureCollection(objects) if len(objects) > 0 else None
          request.response.status_int = 201
          return collection
docs: Read the GeoJSON feature collection from the request body and
              create new objects in the database.