code: def _get_entity(entity_id):
          
          entity_type = g.request_dict['type']
          if entity_type == 'file':
              return model.FileRecord.from_dict(g.request_dict['file'])
          elif entity_type == 'metadata':
              return model.ObservatoryMetadata.from_dict(g.request_dict['metadata'])
          elif entity_type == 'observation':
              return model.Observation.from_dict(g.request_dict['observation'])
          else:
              return None
docs: Uses the request context to retrieve a :class:`meteorpi_model.CameraStatus`, :class:`meteorpi_model.Event` or
          :class:`meteorpi_model.FileRecord` from the POSTed JSON string.
  
          :param string entity_id:
              The ID of a CameraStatus, Event or FileRecord contained within the request
          :return:
              The corresponding entity from the request.