server/edition.py
author Julien Cristau <julien.cristau@logilab.fr>
Thu, 10 Dec 2015 16:58:45 +0100
changeset 10997 da712d3f0601
parent 10903 da30851f9706
permissions -rw-r--r--
Bring back the separate web-side entity cache Prior to changeset 635cfac73d28 "[repoapi] fold ClientConnection into Connection", we had two entity caches: one on the client/dbapi/web side, and one on the server/repo side. This is a waste, but it is actually needed as long as we have the magic _cw attribute on entities which must sometimes be a request and sometimes a cnx. Removing the duplication caused weird problems with entity._cw alternating between both types of objects, which is unexpected by both the repo and the web sides. We add an entity cache on ConnectionCubicWebRequestBase, separate from the Connection's, and bring back the _cw_update_attr_cache/dont-cache-attrs mechanism, to let the server/edition code let caches know which attributes have been modified Entity.as_rset can be cached again, as ResultSet no longer modifies the entity when fetching it from a cache. Contrary to the pre-3.21 code, _cw_update_attr_cache now handles web requests and connections in the same way (otherwise the cache ends up with wrong values if a hook modifies attributes), but dont-cache-attrs is never set for (inlined) relations. Closes #6863543

# copyright 2003-2012 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
"""helper classes to handle server-side edition of entities"""
__docformat__ = "restructuredtext en"

from copy import copy
from yams import ValidationError


_MARKER = object()

class dict_protocol_catcher(object):
    def __init__(self, entity):
        self.__entity = entity
    def __getitem__(self, attr):
        return self.__entity.cw_edited[attr]
    def __setitem__(self, attr, value):
        self.__entity.cw_edited[attr] = value
    def __getattr__(self, attr):
        return getattr(self.__entity, attr)


class EditedEntity(dict):
    """encapsulate entities attributes being written by an RQL query"""
    def __init__(self, entity, **kwargs):
        super(EditedEntity, self).__init__(**kwargs)
        self.entity = entity
        self.skip_security = set()
        self.querier_pending_relations = {}
        self.saved = False

    def __hash__(self):
        # dict|set keyable
        return hash(id(self))

    def __lt__(self, other):
        # we don't want comparison by value inherited from dict
        raise NotImplementedError

    def __eq__(self, other):
        return self is other

    def __ne__(self, other):
        return not (self == other)

    def __setitem__(self, attr, value):
        assert attr != 'eid'
        # don't add attribute into skip_security if already in edited
        # attributes, else we may accidentally skip a desired security check
        if attr not in self:
            self.skip_security.add(attr)
        self.edited_attribute(attr, value)

    def __delitem__(self, attr):
        assert not self.saved, 'too late to modify edited attributes'
        super(EditedEntity, self).__delitem__(attr)
        self.entity.cw_attr_cache.pop(attr, None)

    def __copy__(self):
        # default copy protocol fails in EditedEntity.__setitem__ because
        # copied entity has no skip_security attribute at this point
        return EditedEntity(self.entity, **self)

    def pop(self, attr, *args):
        # don't update skip_security by design (think to storage api)
        assert not self.saved, 'too late to modify edited attributes'
        value = super(EditedEntity, self).pop(attr, *args)
        self.entity.cw_attr_cache.pop(attr, *args)
        return value

    def setdefault(self, attr, default):
        assert attr != 'eid'
        # don't add attribute into skip_security if already in edited
        # attributes, else we may accidentally skip a desired security check
        if attr not in self:
            self[attr] = default
        return self[attr]

    def update(self, values, skipsec=True):
        if skipsec:
            setitem = self.__setitem__
        else:
            setitem = self.edited_attribute
        for attr, value in values.items():
            setitem(attr, value)

    def edited_attribute(self, attr, value):
        """attribute being edited by a rql query: should'nt be added to
        skip_security
        """
        assert not self.saved, 'too late to modify edited attributes'
        super(EditedEntity, self).__setitem__(attr, value)
        self.entity.cw_attr_cache[attr] = value
        if self.entity._cw.vreg.schema.rschema(attr).final:
            self.entity._cw_dont_cache_attribute(attr)

    def oldnewvalue(self, attr):
        """returns the couple (old attr value, new attr value)

        NOTE: will only work in a before_update_entity hook
        """
        assert not self.saved, 'too late to get the old value'
        # get new value and remove from local dict to force a db query to
        # fetch old value
        newvalue = self.entity.cw_attr_cache.pop(attr, _MARKER)
        oldvalue = getattr(self.entity, attr)
        if newvalue is not _MARKER:
            self.entity.cw_attr_cache[attr] = newvalue
        else:
            newvalue = oldvalue
        return oldvalue, newvalue

    def set_defaults(self):
        """set default values according to the schema"""
        for attr, value in self.entity.e_schema.defaults():
            if not attr in self:
                self[str(attr)] = value

    def check(self, creation=False):
        """check the entity edition against its schema. Only final relation
        are checked here, constraint on actual relations are checked in hooks
        """
        entity = self.entity
        if creation:
            # on creations, we want to check all relations, especially
            # required attributes
            relations = [rschema for rschema in entity.e_schema.subject_relations()
                         if rschema.final and rschema.type != 'eid']
        else:
            relations = [entity._cw.vreg.schema.rschema(rtype)
                         for rtype in self]
        try:
            entity.e_schema.check(dict_protocol_catcher(entity),
                                  creation=creation, relations=relations)
        except ValidationError as ex:
            ex.entity = self.entity.eid
            raise

    def clone(self):
        thecopy = EditedEntity(copy(self.entity))
        thecopy.entity.cw_attr_cache = copy(self.entity.cw_attr_cache)
        thecopy.entity._cw_related_cache = {}
        thecopy.update(self, skipsec=False)
        return thecopy