Source code for kuha_osmh_repo_handler.response

#!/usr/bin/env python3
# Author(s): Toni Sissala
# Copyright 2020 Finnish Social Science Data Archive FSD / University of Tampere
# Licensed under the EUPL. See LICENSE.txt for full license.
"""Build responses containing OSMH records.
"""

from functools import partial


class RecordsResponse:
    """Response containing records.

    Provides methods that can be used as callbacks to
    :obj:`kuha_common.query.QueryController`. Uses OSMH records
    defined in :mod:`kuha_osmh_repo_handler.osmh.records`.
    Stores these records for later processing.
    """
    def __init__(self):
        self.records = []
        self.payloads = []

    def _append_record(self, record_constructor, ds_payload):
        if ds_payload:
            self.records.append(record_constructor(ds_payload))

    def _append_payload(self, record_constructor, ds_payload):
        if ds_payload:
            self.payloads.append(record_constructor(ds_payload).get_payload())

    def iterate_records(self):
        """Iterate throught records gathered to response.

        :returns: generator for iterating records.
        """
        for _rec in self.records:
            yield _rec

    def get_record_appender(self, record_constructor):
        """Get record appender function.

        Records that are appended are constructed by using the
        record_constructor parameter.

        :returns: callback function for appending records that get constructed by
                  submitting the receiver parameter to given record_constructor.
        :rtype: :class:`functools.partial`
        """
        return partial(self._append_record, record_constructor)

    def get_payload_appender(self, record_constructor):
        """Get payload appender function.

        Records that are appended are constructed by using the
        record_constructor parameter. After constructing the record,
        calls the constructed record-objects get_payload() method.

        :returns: callback function for appending records that get constructed by
                  submitting the receiver parameter to given record_constructor.
        :rtype: :class:`functools.partial`
        """
        return partial(self._append_payload, record_constructor)

    def get_response(self):
        """Build and return the response as a list of dictionary payloads.

        :returns: record payloads
        :rtype: list
        """
        if self.records:
            for rec in self.iterate_records():
                self.payloads.append(rec.get_payload())
        return self.payloads

    def get_single_response(self):
        """Get single response payload.

        :note: After calling this method the payloads list will be empty.

        :returns: single record's payload.
        :rtype: dict
        :raises: :exc:`ValueError` if contained payloads list has more than a single cell.
        """
        payloads = self.get_response()
        lenght = len(self.payloads)
        if lenght > 1:
            # This is a coding error. One should call this method only when excepting a single record.
            raise ValueError('Excpecting a single value, but payloads has multiple')
        elif lenght < 1:
            return {} # return dict so that it may be encoded to json
        return payloads.pop()