673 lines
23 KiB
Python
673 lines
23 KiB
Python
# orm/unitofwork.py
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# Copyright (C) 2005-2017 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""The internals for the unit of work system.
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The session's flush() process passes objects to a contextual object
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here, which assembles flush tasks based on mappers and their properties,
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organizes them in order of dependency, and executes.
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"""
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from .. import util, event
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from ..util import topological
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from . import attributes, persistence, util as orm_util
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from . import exc as orm_exc
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import itertools
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def track_cascade_events(descriptor, prop):
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"""Establish event listeners on object attributes which handle
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cascade-on-set/append.
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"""
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key = prop.key
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def append(state, item, initiator):
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# process "save_update" cascade rules for when
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# an instance is appended to the list of another instance
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if item is None:
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return
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sess = state.session
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if sess:
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if sess._warn_on_events:
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sess._flush_warning("collection append")
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prop = state.manager.mapper._props[key]
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item_state = attributes.instance_state(item)
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if prop._cascade.save_update and \
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(prop.cascade_backrefs or key == initiator.key) and \
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not sess._contains_state(item_state):
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sess._save_or_update_state(item_state)
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return item
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def remove(state, item, initiator):
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if item is None:
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return
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sess = state.session
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if sess:
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prop = state.manager.mapper._props[key]
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if sess._warn_on_events:
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sess._flush_warning(
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"collection remove"
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if prop.uselist
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else "related attribute delete")
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# expunge pending orphans
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item_state = attributes.instance_state(item)
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if prop._cascade.delete_orphan and \
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item_state in sess._new and \
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prop.mapper._is_orphan(item_state):
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sess.expunge(item)
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def set_(state, newvalue, oldvalue, initiator):
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# process "save_update" cascade rules for when an instance
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# is attached to another instance
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if oldvalue is newvalue:
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return newvalue
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sess = state.session
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if sess:
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if sess._warn_on_events:
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sess._flush_warning("related attribute set")
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prop = state.manager.mapper._props[key]
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if newvalue is not None:
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newvalue_state = attributes.instance_state(newvalue)
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if prop._cascade.save_update and \
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(prop.cascade_backrefs or key == initiator.key) and \
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not sess._contains_state(newvalue_state):
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sess._save_or_update_state(newvalue_state)
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if oldvalue is not None and \
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oldvalue is not attributes.NEVER_SET and \
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oldvalue is not attributes.PASSIVE_NO_RESULT and \
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prop._cascade.delete_orphan:
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# possible to reach here with attributes.NEVER_SET ?
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oldvalue_state = attributes.instance_state(oldvalue)
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if oldvalue_state in sess._new and \
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prop.mapper._is_orphan(oldvalue_state):
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sess.expunge(oldvalue)
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return newvalue
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event.listen(descriptor, 'append', append, raw=True, retval=True)
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event.listen(descriptor, 'remove', remove, raw=True, retval=True)
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event.listen(descriptor, 'set', set_, raw=True, retval=True)
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class UOWTransaction(object):
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def __init__(self, session):
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self.session = session
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# dictionary used by external actors to
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# store arbitrary state information.
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self.attributes = {}
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# dictionary of mappers to sets of
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# DependencyProcessors, which are also
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# set to be part of the sorted flush actions,
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# which have that mapper as a parent.
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self.deps = util.defaultdict(set)
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# dictionary of mappers to sets of InstanceState
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# items pending for flush which have that mapper
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# as a parent.
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self.mappers = util.defaultdict(set)
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# a dictionary of Preprocess objects, which gather
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# additional states impacted by the flush
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# and determine if a flush action is needed
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self.presort_actions = {}
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# dictionary of PostSortRec objects, each
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# one issues work during the flush within
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# a certain ordering.
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self.postsort_actions = {}
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# a set of 2-tuples, each containing two
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# PostSortRec objects where the second
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# is dependent on the first being executed
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# first
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self.dependencies = set()
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# dictionary of InstanceState-> (isdelete, listonly)
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# tuples, indicating if this state is to be deleted
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# or insert/updated, or just refreshed
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self.states = {}
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# tracks InstanceStates which will be receiving
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# a "post update" call. Keys are mappers,
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# values are a set of states and a set of the
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# columns which should be included in the update.
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self.post_update_states = util.defaultdict(lambda: (set(), set()))
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@property
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def has_work(self):
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return bool(self.states)
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def was_already_deleted(self, state):
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"""return true if the given state is expired and was deleted
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previously.
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"""
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if state.expired:
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try:
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state._load_expired(state, attributes.PASSIVE_OFF)
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except orm_exc.ObjectDeletedError:
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self.session._remove_newly_deleted([state])
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return True
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return False
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def is_deleted(self, state):
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"""return true if the given state is marked as deleted
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within this uowtransaction."""
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return state in self.states and self.states[state][0]
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def memo(self, key, callable_):
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if key in self.attributes:
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return self.attributes[key]
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else:
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self.attributes[key] = ret = callable_()
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return ret
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def remove_state_actions(self, state):
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"""remove pending actions for a state from the uowtransaction."""
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isdelete = self.states[state][0]
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self.states[state] = (isdelete, True)
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def get_attribute_history(self, state, key,
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passive=attributes.PASSIVE_NO_INITIALIZE):
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"""facade to attributes.get_state_history(), including
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caching of results."""
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hashkey = ("history", state, key)
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# cache the objects, not the states; the strong reference here
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# prevents newly loaded objects from being dereferenced during the
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# flush process
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if hashkey in self.attributes:
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history, state_history, cached_passive = self.attributes[hashkey]
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# if the cached lookup was "passive" and now
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# we want non-passive, do a non-passive lookup and re-cache
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if not cached_passive & attributes.SQL_OK \
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and passive & attributes.SQL_OK:
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impl = state.manager[key].impl
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history = impl.get_history(state, state.dict,
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attributes.PASSIVE_OFF |
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attributes.LOAD_AGAINST_COMMITTED)
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if history and impl.uses_objects:
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state_history = history.as_state()
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else:
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state_history = history
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self.attributes[hashkey] = (history, state_history, passive)
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else:
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impl = state.manager[key].impl
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# TODO: store the history as (state, object) tuples
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# so we don't have to keep converting here
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history = impl.get_history(state, state.dict, passive |
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attributes.LOAD_AGAINST_COMMITTED)
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if history and impl.uses_objects:
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state_history = history.as_state()
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else:
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state_history = history
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self.attributes[hashkey] = (history, state_history,
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passive)
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return state_history
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def has_dep(self, processor):
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return (processor, True) in self.presort_actions
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def register_preprocessor(self, processor, fromparent):
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key = (processor, fromparent)
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if key not in self.presort_actions:
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self.presort_actions[key] = Preprocess(processor, fromparent)
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def register_object(self, state, isdelete=False,
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listonly=False, cancel_delete=False,
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operation=None, prop=None):
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if not self.session._contains_state(state):
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# this condition is normal when objects are registered
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# as part of a relationship cascade operation. it should
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# not occur for the top-level register from Session.flush().
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if not state.deleted and operation is not None:
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util.warn("Object of type %s not in session, %s operation "
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"along '%s' will not proceed" %
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(orm_util.state_class_str(state), operation, prop))
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return False
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if state not in self.states:
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mapper = state.manager.mapper
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if mapper not in self.mappers:
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self._per_mapper_flush_actions(mapper)
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self.mappers[mapper].add(state)
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self.states[state] = (isdelete, listonly)
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else:
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if not listonly and (isdelete or cancel_delete):
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self.states[state] = (isdelete, False)
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return True
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def issue_post_update(self, state, post_update_cols):
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mapper = state.manager.mapper.base_mapper
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states, cols = self.post_update_states[mapper]
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states.add(state)
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cols.update(post_update_cols)
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def _per_mapper_flush_actions(self, mapper):
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saves = SaveUpdateAll(self, mapper.base_mapper)
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deletes = DeleteAll(self, mapper.base_mapper)
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self.dependencies.add((saves, deletes))
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for dep in mapper._dependency_processors:
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dep.per_property_preprocessors(self)
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for prop in mapper.relationships:
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if prop.viewonly:
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continue
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dep = prop._dependency_processor
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dep.per_property_preprocessors(self)
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@util.memoized_property
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def _mapper_for_dep(self):
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"""return a dynamic mapping of (Mapper, DependencyProcessor) to
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True or False, indicating if the DependencyProcessor operates
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on objects of that Mapper.
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The result is stored in the dictionary persistently once
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calculated.
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"""
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return util.PopulateDict(
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lambda tup: tup[0]._props.get(tup[1].key) is tup[1].prop
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)
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def filter_states_for_dep(self, dep, states):
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"""Filter the given list of InstanceStates to those relevant to the
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given DependencyProcessor.
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"""
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mapper_for_dep = self._mapper_for_dep
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return [s for s in states if mapper_for_dep[(s.manager.mapper, dep)]]
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def states_for_mapper_hierarchy(self, mapper, isdelete, listonly):
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checktup = (isdelete, listonly)
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for mapper in mapper.base_mapper.self_and_descendants:
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for state in self.mappers[mapper]:
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if self.states[state] == checktup:
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yield state
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def _generate_actions(self):
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"""Generate the full, unsorted collection of PostSortRecs as
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well as dependency pairs for this UOWTransaction.
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"""
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# execute presort_actions, until all states
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# have been processed. a presort_action might
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# add new states to the uow.
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while True:
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ret = False
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for action in list(self.presort_actions.values()):
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if action.execute(self):
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ret = True
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if not ret:
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break
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# see if the graph of mapper dependencies has cycles.
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self.cycles = cycles = topological.find_cycles(
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self.dependencies,
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list(self.postsort_actions.values()))
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if cycles:
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# if yes, break the per-mapper actions into
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# per-state actions
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convert = dict(
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(rec, set(rec.per_state_flush_actions(self)))
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for rec in cycles
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)
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# rewrite the existing dependencies to point to
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# the per-state actions for those per-mapper actions
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# that were broken up.
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for edge in list(self.dependencies):
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if None in edge or \
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edge[0].disabled or edge[1].disabled or \
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cycles.issuperset(edge):
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self.dependencies.remove(edge)
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elif edge[0] in cycles:
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self.dependencies.remove(edge)
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for dep in convert[edge[0]]:
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self.dependencies.add((dep, edge[1]))
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elif edge[1] in cycles:
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self.dependencies.remove(edge)
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for dep in convert[edge[1]]:
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self.dependencies.add((edge[0], dep))
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return set([a for a in self.postsort_actions.values()
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if not a.disabled
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]
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).difference(cycles)
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def execute(self):
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postsort_actions = self._generate_actions()
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# sort = topological.sort(self.dependencies, postsort_actions)
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# print "--------------"
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# print "\ndependencies:", self.dependencies
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# print "\ncycles:", self.cycles
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# print "\nsort:", list(sort)
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# print "\nCOUNT OF POSTSORT ACTIONS", len(postsort_actions)
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# execute
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if self.cycles:
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for set_ in topological.sort_as_subsets(
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self.dependencies,
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postsort_actions):
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while set_:
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n = set_.pop()
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n.execute_aggregate(self, set_)
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else:
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for rec in topological.sort(
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self.dependencies,
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postsort_actions):
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rec.execute(self)
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def finalize_flush_changes(self):
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"""mark processed objects as clean / deleted after a successful
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flush().
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this method is called within the flush() method after the
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execute() method has succeeded and the transaction has been committed.
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"""
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if not self.states:
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return
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states = set(self.states)
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isdel = set(
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s for (s, (isdelete, listonly)) in self.states.items()
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if isdelete
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)
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other = states.difference(isdel)
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if isdel:
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self.session._remove_newly_deleted(isdel)
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if other:
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self.session._register_newly_persistent(other)
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class IterateMappersMixin(object):
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def _mappers(self, uow):
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if self.fromparent:
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return iter(
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m for m in
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self.dependency_processor.parent.self_and_descendants
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if uow._mapper_for_dep[(m, self.dependency_processor)]
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)
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else:
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return self.dependency_processor.mapper.self_and_descendants
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class Preprocess(IterateMappersMixin):
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def __init__(self, dependency_processor, fromparent):
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self.dependency_processor = dependency_processor
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self.fromparent = fromparent
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self.processed = set()
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self.setup_flush_actions = False
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def execute(self, uow):
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delete_states = set()
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save_states = set()
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for mapper in self._mappers(uow):
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for state in uow.mappers[mapper].difference(self.processed):
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(isdelete, listonly) = uow.states[state]
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if not listonly:
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if isdelete:
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delete_states.add(state)
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else:
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save_states.add(state)
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if delete_states:
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self.dependency_processor.presort_deletes(uow, delete_states)
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self.processed.update(delete_states)
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if save_states:
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self.dependency_processor.presort_saves(uow, save_states)
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self.processed.update(save_states)
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if (delete_states or save_states):
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if not self.setup_flush_actions and (
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self.dependency_processor.
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prop_has_changes(uow, delete_states, True) or
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self.dependency_processor.
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prop_has_changes(uow, save_states, False)
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):
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self.dependency_processor.per_property_flush_actions(uow)
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self.setup_flush_actions = True
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return True
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else:
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return False
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class PostSortRec(object):
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disabled = False
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def __new__(cls, uow, *args):
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key = (cls, ) + args
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if key in uow.postsort_actions:
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return uow.postsort_actions[key]
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else:
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uow.postsort_actions[key] = \
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ret = \
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object.__new__(cls)
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return ret
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def execute_aggregate(self, uow, recs):
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self.execute(uow)
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def __repr__(self):
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return "%s(%s)" % (
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self.__class__.__name__,
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",".join(str(x) for x in self.__dict__.values())
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)
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class ProcessAll(IterateMappersMixin, PostSortRec):
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def __init__(self, uow, dependency_processor, delete, fromparent):
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self.dependency_processor = dependency_processor
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self.delete = delete
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self.fromparent = fromparent
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uow.deps[dependency_processor.parent.base_mapper].\
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add(dependency_processor)
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def execute(self, uow):
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states = self._elements(uow)
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if self.delete:
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self.dependency_processor.process_deletes(uow, states)
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else:
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self.dependency_processor.process_saves(uow, states)
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def per_state_flush_actions(self, uow):
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# this is handled by SaveUpdateAll and DeleteAll,
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# since a ProcessAll should unconditionally be pulled
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# into per-state if either the parent/child mappers
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# are part of a cycle
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return iter([])
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def __repr__(self):
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return "%s(%s, delete=%s)" % (
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self.__class__.__name__,
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self.dependency_processor,
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self.delete
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)
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def _elements(self, uow):
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for mapper in self._mappers(uow):
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for state in uow.mappers[mapper]:
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(isdelete, listonly) = uow.states[state]
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if isdelete == self.delete and not listonly:
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yield state
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class IssuePostUpdate(PostSortRec):
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def __init__(self, uow, mapper, isdelete):
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self.mapper = mapper
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self.isdelete = isdelete
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def execute(self, uow):
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states, cols = uow.post_update_states[self.mapper]
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states = [s for s in states if uow.states[s][0] == self.isdelete]
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persistence.post_update(self.mapper, states, uow, cols)
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class SaveUpdateAll(PostSortRec):
|
|
def __init__(self, uow, mapper):
|
|
self.mapper = mapper
|
|
assert mapper is mapper.base_mapper
|
|
|
|
def execute(self, uow):
|
|
persistence.save_obj(self.mapper,
|
|
uow.states_for_mapper_hierarchy(
|
|
self.mapper, False, False),
|
|
uow
|
|
)
|
|
|
|
def per_state_flush_actions(self, uow):
|
|
states = list(uow.states_for_mapper_hierarchy(
|
|
self.mapper, False, False))
|
|
base_mapper = self.mapper.base_mapper
|
|
delete_all = DeleteAll(uow, base_mapper)
|
|
for state in states:
|
|
# keep saves before deletes -
|
|
# this ensures 'row switch' operations work
|
|
action = SaveUpdateState(uow, state, base_mapper)
|
|
uow.dependencies.add((action, delete_all))
|
|
yield action
|
|
|
|
for dep in uow.deps[self.mapper]:
|
|
states_for_prop = uow.filter_states_for_dep(dep, states)
|
|
dep.per_state_flush_actions(uow, states_for_prop, False)
|
|
|
|
|
|
class DeleteAll(PostSortRec):
|
|
def __init__(self, uow, mapper):
|
|
self.mapper = mapper
|
|
assert mapper is mapper.base_mapper
|
|
|
|
def execute(self, uow):
|
|
persistence.delete_obj(self.mapper,
|
|
uow.states_for_mapper_hierarchy(
|
|
self.mapper, True, False),
|
|
uow
|
|
)
|
|
|
|
def per_state_flush_actions(self, uow):
|
|
states = list(uow.states_for_mapper_hierarchy(
|
|
self.mapper, True, False))
|
|
base_mapper = self.mapper.base_mapper
|
|
save_all = SaveUpdateAll(uow, base_mapper)
|
|
for state in states:
|
|
# keep saves before deletes -
|
|
# this ensures 'row switch' operations work
|
|
action = DeleteState(uow, state, base_mapper)
|
|
uow.dependencies.add((save_all, action))
|
|
yield action
|
|
|
|
for dep in uow.deps[self.mapper]:
|
|
states_for_prop = uow.filter_states_for_dep(dep, states)
|
|
dep.per_state_flush_actions(uow, states_for_prop, True)
|
|
|
|
|
|
class ProcessState(PostSortRec):
|
|
def __init__(self, uow, dependency_processor, delete, state):
|
|
self.dependency_processor = dependency_processor
|
|
self.delete = delete
|
|
self.state = state
|
|
|
|
def execute_aggregate(self, uow, recs):
|
|
cls_ = self.__class__
|
|
dependency_processor = self.dependency_processor
|
|
delete = self.delete
|
|
our_recs = [r for r in recs
|
|
if r.__class__ is cls_ and
|
|
r.dependency_processor is dependency_processor and
|
|
r.delete is delete]
|
|
recs.difference_update(our_recs)
|
|
states = [self.state] + [r.state for r in our_recs]
|
|
if delete:
|
|
dependency_processor.process_deletes(uow, states)
|
|
else:
|
|
dependency_processor.process_saves(uow, states)
|
|
|
|
def __repr__(self):
|
|
return "%s(%s, %s, delete=%s)" % (
|
|
self.__class__.__name__,
|
|
self.dependency_processor,
|
|
orm_util.state_str(self.state),
|
|
self.delete
|
|
)
|
|
|
|
|
|
class SaveUpdateState(PostSortRec):
|
|
def __init__(self, uow, state, mapper):
|
|
self.state = state
|
|
self.mapper = mapper
|
|
|
|
def execute_aggregate(self, uow, recs):
|
|
cls_ = self.__class__
|
|
mapper = self.mapper
|
|
our_recs = [r for r in recs
|
|
if r.__class__ is cls_ and
|
|
r.mapper is mapper]
|
|
recs.difference_update(our_recs)
|
|
persistence.save_obj(mapper,
|
|
[self.state] +
|
|
[r.state for r in our_recs],
|
|
uow)
|
|
|
|
def __repr__(self):
|
|
return "%s(%s)" % (
|
|
self.__class__.__name__,
|
|
orm_util.state_str(self.state)
|
|
)
|
|
|
|
|
|
class DeleteState(PostSortRec):
|
|
def __init__(self, uow, state, mapper):
|
|
self.state = state
|
|
self.mapper = mapper
|
|
|
|
def execute_aggregate(self, uow, recs):
|
|
cls_ = self.__class__
|
|
mapper = self.mapper
|
|
our_recs = [r for r in recs
|
|
if r.__class__ is cls_ and
|
|
r.mapper is mapper]
|
|
recs.difference_update(our_recs)
|
|
states = [self.state] + [r.state for r in our_recs]
|
|
persistence.delete_obj(mapper,
|
|
[s for s in states if uow.states[s][0]],
|
|
uow)
|
|
|
|
def __repr__(self):
|
|
return "%s(%s)" % (
|
|
self.__class__.__name__,
|
|
orm_util.state_str(self.state)
|
|
)
|