Source code for invenio_pidstore.resolver

# -*- coding: utf-8 -*-
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# This file is part of Invenio.
# Copyright (C) 2015, 2016 CERN.
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"""Internal resolver for persistent identifiers."""

from __future__ import absolute_import, print_function

from sqlalchemy.orm.exc import NoResultFound

from .errors import PIDDeletedError, PIDMissingObjectError, \
    PIDRedirectedError, PIDUnregistered
from .models import PersistentIdentifier


class Resolver(object):
    """Persistent identifier resolver.

    Helper class for retrieving an internal object for a given persistent
    identifier.
    """

    def __init__(self, pid_type=None, object_type=None, getter=None):
        """Initialize resolver.

        :param pid_type: Persistent identifier type.
        :param object_type: Object type.
        :param getter: Callable that will take an object id for the given
            object type and retrieve the internal object.
        """
        self.pid_type = pid_type
        self.object_type = object_type
        self.object_getter = getter

    def resolve(self, pid_value):
        """Resolve a persistent identifier to an internal object.

        :param pid_value: Persistent identifier.
        :returns: A tuple containing (pid, object).
        """
        pid = PersistentIdentifier.get(self.pid_type, pid_value)

        if pid.is_new() or pid.is_reserved():
            raise PIDUnregistered(pid)

        if pid.is_deleted():
            obj_id = pid.get_assigned_object(object_type=self.object_type)
            try:
                obj = self.object_getter(obj_id) if obj_id else None
            except NoResultFound:
                obj = None
            raise PIDDeletedError(pid, obj)

        if pid.is_redirected():
            raise PIDRedirectedError(pid, pid.get_redirect())

        obj_id = pid.get_assigned_object(object_type=self.object_type)
        if not obj_id:
            raise PIDMissingObjectError(self.pid_type, pid_value)

        return pid, self.object_getter(obj_id)