1460 lines
55 KiB
Python
1460 lines
55 KiB
Python
# orm/strategies.py
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# Copyright (C) 2005-2014 the SQLAlchemy authors and contributors <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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"""sqlalchemy.orm.interfaces.LoaderStrategy
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implementations, and related MapperOptions."""
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from .. import exc as sa_exc, inspect
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from .. import util, log, event
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from ..sql import util as sql_util, visitors
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from .. import sql
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from . import (
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attributes, interfaces, exc as orm_exc, loading,
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unitofwork, util as orm_util
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)
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from .state import InstanceState
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from .util import _none_set
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from . import properties
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from .interfaces import (
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LoaderStrategy, StrategizedProperty
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)
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from .session import _state_session
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import itertools
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def _register_attribute(strategy, mapper, useobject,
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compare_function=None,
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typecallable=None,
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uselist=False,
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callable_=None,
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proxy_property=None,
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active_history=False,
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impl_class=None,
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**kw
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):
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prop = strategy.parent_property
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attribute_ext = list(util.to_list(prop.extension, default=[]))
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listen_hooks = []
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if useobject and prop.single_parent:
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listen_hooks.append(single_parent_validator)
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if prop.key in prop.parent.validators:
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fn, opts = prop.parent.validators[prop.key]
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listen_hooks.append(
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lambda desc, prop: orm_util._validator_events(desc,
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prop.key, fn, **opts)
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)
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if useobject:
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listen_hooks.append(unitofwork.track_cascade_events)
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# need to assemble backref listeners
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# after the singleparentvalidator, mapper validator
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backref = kw.pop('backref', None)
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if backref:
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listen_hooks.append(
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lambda desc, prop: attributes.backref_listeners(desc,
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backref,
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uselist)
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)
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for m in mapper.self_and_descendants:
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if prop is m._props.get(prop.key):
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desc = attributes.register_attribute_impl(
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m.class_,
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prop.key,
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parent_token=prop,
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uselist=uselist,
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compare_function=compare_function,
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useobject=useobject,
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extension=attribute_ext,
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trackparent=useobject and (prop.single_parent
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or prop.direction is interfaces.ONETOMANY),
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typecallable=typecallable,
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callable_=callable_,
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active_history=active_history,
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impl_class=impl_class,
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send_modified_events=not useobject or not prop.viewonly,
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doc=prop.doc,
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**kw
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)
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for hook in listen_hooks:
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hook(desc, prop)
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@properties.ColumnProperty.strategy_for(instrument=False, deferred=False)
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class UninstrumentedColumnLoader(LoaderStrategy):
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"""Represent the a non-instrumented MapperProperty.
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The polymorphic_on argument of mapper() often results in this,
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if the argument is against the with_polymorphic selectable.
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"""
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def __init__(self, parent):
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super(UninstrumentedColumnLoader, self).__init__(parent)
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self.columns = self.parent_property.columns
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def setup_query(self, context, entity, path, loadopt, adapter,
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column_collection=None, **kwargs):
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for c in self.columns:
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if adapter:
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c = adapter.columns[c]
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column_collection.append(c)
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def create_row_processor(self, context, path, loadopt, mapper, row, adapter):
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return None, None, None
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@log.class_logger
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@properties.ColumnProperty.strategy_for(instrument=True, deferred=False)
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class ColumnLoader(LoaderStrategy):
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"""Provide loading behavior for a :class:`.ColumnProperty`."""
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def __init__(self, parent):
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super(ColumnLoader, self).__init__(parent)
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self.columns = self.parent_property.columns
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self.is_composite = hasattr(self.parent_property, 'composite_class')
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def setup_query(self, context, entity, path, loadopt,
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adapter, column_collection, **kwargs):
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for c in self.columns:
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if adapter:
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c = adapter.columns[c]
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column_collection.append(c)
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def init_class_attribute(self, mapper):
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self.is_class_level = True
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coltype = self.columns[0].type
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# TODO: check all columns ? check for foreign key as well?
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active_history = self.parent_property.active_history or \
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self.columns[0].primary_key or \
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mapper.version_id_col in set(self.columns)
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_register_attribute(self, mapper, useobject=False,
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compare_function=coltype.compare_values,
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active_history=active_history
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)
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def create_row_processor(self, context, path,
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loadopt, mapper, row, adapter):
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key = self.key
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# look through list of columns represented here
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# to see which, if any, is present in the row.
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for col in self.columns:
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if adapter:
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col = adapter.columns[col]
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if col is not None and col in row:
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def fetch_col(state, dict_, row):
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dict_[key] = row[col]
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return fetch_col, None, None
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else:
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def expire_for_non_present_col(state, dict_, row):
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state._expire_attribute_pre_commit(dict_, key)
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return expire_for_non_present_col, None, None
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@log.class_logger
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@properties.ColumnProperty.strategy_for(deferred=True, instrument=True)
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class DeferredColumnLoader(LoaderStrategy):
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"""Provide loading behavior for a deferred :class:`.ColumnProperty`."""
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def __init__(self, parent):
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super(DeferredColumnLoader, self).__init__(parent)
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if hasattr(self.parent_property, 'composite_class'):
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raise NotImplementedError("Deferred loading for composite "
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"types not implemented yet")
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self.columns = self.parent_property.columns
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self.group = self.parent_property.group
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def create_row_processor(self, context, path, loadopt, mapper, row, adapter):
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col = self.columns[0]
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if adapter:
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col = adapter.columns[col]
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key = self.key
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if col in row:
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return self.parent_property._get_strategy_by_cls(ColumnLoader).\
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create_row_processor(
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context, path, loadopt, mapper, row, adapter)
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elif not self.is_class_level:
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set_deferred_for_local_state = InstanceState._row_processor(
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mapper.class_manager,
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LoadDeferredColumns(key), key)
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return set_deferred_for_local_state, None, None
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else:
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def reset_col_for_deferred(state, dict_, row):
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# reset state on the key so that deferred callables
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# fire off on next access.
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state._reset(dict_, key)
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return reset_col_for_deferred, None, None
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def init_class_attribute(self, mapper):
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self.is_class_level = True
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_register_attribute(self, mapper, useobject=False,
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compare_function=self.columns[0].type.compare_values,
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callable_=self._load_for_state,
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expire_missing=False
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)
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def setup_query(self, context, entity, path, loadopt, adapter,
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only_load_props=None, **kwargs):
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if (
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loadopt and self.group and
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loadopt.local_opts.get('undefer_group', False) == self.group
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) or (only_load_props and self.key in only_load_props):
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self.parent_property._get_strategy_by_cls(ColumnLoader).\
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setup_query(context, entity,
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path, loadopt, adapter, **kwargs)
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def _load_for_state(self, state, passive):
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if not state.key:
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return attributes.ATTR_EMPTY
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if not passive & attributes.SQL_OK:
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return attributes.PASSIVE_NO_RESULT
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localparent = state.manager.mapper
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if self.group:
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toload = [
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p.key for p in
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localparent.iterate_properties
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if isinstance(p, StrategizedProperty) and
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isinstance(p.strategy, DeferredColumnLoader) and
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p.group == self.group
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]
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else:
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toload = [self.key]
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# narrow the keys down to just those which have no history
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group = [k for k in toload if k in state.unmodified]
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session = _state_session(state)
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if session is None:
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raise orm_exc.DetachedInstanceError(
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"Parent instance %s is not bound to a Session; "
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"deferred load operation of attribute '%s' cannot proceed" %
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(orm_util.state_str(state), self.key)
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)
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query = session.query(localparent)
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if loading.load_on_ident(query, state.key,
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only_load_props=group, refresh_state=state) is None:
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raise orm_exc.ObjectDeletedError(state)
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return attributes.ATTR_WAS_SET
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class LoadDeferredColumns(object):
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"""serializable loader object used by DeferredColumnLoader"""
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def __init__(self, key):
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self.key = key
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def __call__(self, state, passive=attributes.PASSIVE_OFF):
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key = self.key
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localparent = state.manager.mapper
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prop = localparent._props[key]
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strategy = prop._strategies[DeferredColumnLoader]
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return strategy._load_for_state(state, passive)
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class AbstractRelationshipLoader(LoaderStrategy):
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"""LoaderStratgies which deal with related objects."""
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def __init__(self, parent):
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super(AbstractRelationshipLoader, self).__init__(parent)
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self.mapper = self.parent_property.mapper
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self.target = self.parent_property.target
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self.uselist = self.parent_property.uselist
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@log.class_logger
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@properties.RelationshipProperty.strategy_for(lazy="noload")
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@properties.RelationshipProperty.strategy_for(lazy=None)
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class NoLoader(AbstractRelationshipLoader):
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"""Provide loading behavior for a :class:`.RelationshipProperty`
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with "lazy=None".
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"""
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def init_class_attribute(self, mapper):
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self.is_class_level = True
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_register_attribute(self, mapper,
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useobject=True,
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uselist=self.parent_property.uselist,
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typecallable=self.parent_property.collection_class,
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)
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def create_row_processor(self, context, path, loadopt, mapper, row, adapter):
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def invoke_no_load(state, dict_, row):
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state._initialize(self.key)
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return invoke_no_load, None, None
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@log.class_logger
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@properties.RelationshipProperty.strategy_for(lazy=True)
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@properties.RelationshipProperty.strategy_for(lazy="select")
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class LazyLoader(AbstractRelationshipLoader):
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"""Provide loading behavior for a :class:`.RelationshipProperty`
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with "lazy=True", that is loads when first accessed.
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"""
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def __init__(self, parent):
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super(LazyLoader, self).__init__(parent)
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join_condition = self.parent_property._join_condition
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self._lazywhere, \
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self._bind_to_col, \
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self._equated_columns = join_condition.create_lazy_clause()
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self._rev_lazywhere, \
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self._rev_bind_to_col, \
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self._rev_equated_columns = join_condition.create_lazy_clause(
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reverse_direction=True)
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self.logger.info("%s lazy loading clause %s", self, self._lazywhere)
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# determine if our "lazywhere" clause is the same as the mapper's
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# get() clause. then we can just use mapper.get()
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self.use_get = not self.uselist and \
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self.mapper._get_clause[0].compare(
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self._lazywhere,
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use_proxies=True,
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equivalents=self.mapper._equivalent_columns
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)
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if self.use_get:
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for col in list(self._equated_columns):
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if col in self.mapper._equivalent_columns:
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for c in self.mapper._equivalent_columns[col]:
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self._equated_columns[c] = self._equated_columns[col]
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self.logger.info("%s will use query.get() to "
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"optimize instance loads" % self)
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def init_class_attribute(self, mapper):
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self.is_class_level = True
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active_history = (
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self.parent_property.active_history or
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self.parent_property.direction is not interfaces.MANYTOONE or
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not self.use_get
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)
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# MANYTOONE currently only needs the
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# "old" value for delete-orphan
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# cascades. the required _SingleParentValidator
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# will enable active_history
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# in that case. otherwise we don't need the
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# "old" value during backref operations.
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_register_attribute(self,
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mapper,
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useobject=True,
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callable_=self._load_for_state,
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uselist=self.parent_property.uselist,
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backref=self.parent_property.back_populates,
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typecallable=self.parent_property.collection_class,
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active_history=active_history
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)
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def lazy_clause(self, state, reverse_direction=False,
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alias_secondary=False,
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adapt_source=None,
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passive=None):
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if state is None:
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return self._lazy_none_clause(
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reverse_direction,
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adapt_source=adapt_source)
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if not reverse_direction:
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criterion, bind_to_col, rev = \
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self._lazywhere, \
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self._bind_to_col, \
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self._equated_columns
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else:
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criterion, bind_to_col, rev = \
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self._rev_lazywhere, \
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self._rev_bind_to_col, \
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self._rev_equated_columns
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if reverse_direction:
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mapper = self.parent_property.mapper
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else:
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mapper = self.parent_property.parent
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o = state.obj() # strong ref
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dict_ = attributes.instance_dict(o)
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# use the "committed state" only if we're in a flush
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# for this state.
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if passive and passive & attributes.LOAD_AGAINST_COMMITTED:
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def visit_bindparam(bindparam):
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if bindparam._identifying_key in bind_to_col:
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bindparam.callable = \
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lambda: mapper._get_committed_state_attr_by_column(
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state, dict_,
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bind_to_col[bindparam._identifying_key])
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else:
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def visit_bindparam(bindparam):
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if bindparam._identifying_key in bind_to_col:
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bindparam.callable = \
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lambda: mapper._get_state_attr_by_column(
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state, dict_,
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bind_to_col[bindparam._identifying_key])
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if self.parent_property.secondary is not None and alias_secondary:
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criterion = sql_util.ClauseAdapter(
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self.parent_property.secondary.alias()).\
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traverse(criterion)
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criterion = visitors.cloned_traverse(
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criterion, {}, {'bindparam': visit_bindparam})
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if adapt_source:
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criterion = adapt_source(criterion)
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return criterion
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def _lazy_none_clause(self, reverse_direction=False, adapt_source=None):
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if not reverse_direction:
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criterion, bind_to_col, rev = \
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self._lazywhere, \
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self._bind_to_col,\
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self._equated_columns
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else:
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criterion, bind_to_col, rev = \
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self._rev_lazywhere, \
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self._rev_bind_to_col, \
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self._rev_equated_columns
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criterion = sql_util.adapt_criterion_to_null(criterion, bind_to_col)
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if adapt_source:
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criterion = adapt_source(criterion)
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return criterion
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def _load_for_state(self, state, passive):
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if not state.key and \
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(
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(
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not self.parent_property.load_on_pending
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and not state._load_pending
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)
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or not state.session_id
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):
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return attributes.ATTR_EMPTY
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pending = not state.key
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ident_key = None
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if (
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(not passive & attributes.SQL_OK and not self.use_get)
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or
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(not passive & attributes.NON_PERSISTENT_OK and pending)
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):
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return attributes.PASSIVE_NO_RESULT
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session = _state_session(state)
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if not session:
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raise orm_exc.DetachedInstanceError(
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"Parent instance %s is not bound to a Session; "
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"lazy load operation of attribute '%s' cannot proceed" %
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(orm_util.state_str(state), self.key)
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)
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# if we have a simple primary key load, check the
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# identity map without generating a Query at all
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if self.use_get:
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ident = self._get_ident_for_use_get(
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session,
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state,
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passive
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)
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if attributes.PASSIVE_NO_RESULT in ident:
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return attributes.PASSIVE_NO_RESULT
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elif attributes.NEVER_SET in ident:
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return attributes.NEVER_SET
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if _none_set.issuperset(ident):
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return None
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ident_key = self.mapper.identity_key_from_primary_key(ident)
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instance = loading.get_from_identity(session, ident_key, passive)
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if instance is not None:
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return instance
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elif not passive & attributes.SQL_OK or \
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not passive & attributes.RELATED_OBJECT_OK:
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return attributes.PASSIVE_NO_RESULT
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return self._emit_lazyload(session, state, ident_key, passive)
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|
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def _get_ident_for_use_get(self, session, state, passive):
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instance_mapper = state.manager.mapper
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if passive & attributes.LOAD_AGAINST_COMMITTED:
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get_attr = instance_mapper._get_committed_state_attr_by_column
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else:
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get_attr = instance_mapper._get_state_attr_by_column
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dict_ = state.dict
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return [
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get_attr(
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state,
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dict_,
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self._equated_columns[pk],
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passive=passive)
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|
for pk in self.mapper.primary_key
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]
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|
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@util.dependencies("sqlalchemy.orm.strategy_options")
|
|
def _emit_lazyload(self, strategy_options, session, state, ident_key, passive):
|
|
q = session.query(self.mapper)._adapt_all_clauses()
|
|
|
|
if self.parent_property.secondary is not None:
|
|
q = q.select_from(self.mapper, self.parent_property.secondary)
|
|
|
|
q = q._with_invoke_all_eagers(False)
|
|
|
|
pending = not state.key
|
|
|
|
# don't autoflush on pending
|
|
if pending or passive & attributes.NO_AUTOFLUSH:
|
|
q = q.autoflush(False)
|
|
|
|
|
|
if state.load_path:
|
|
q = q._with_current_path(state.load_path[self.parent_property])
|
|
|
|
if state.load_options:
|
|
q = q._conditional_options(*state.load_options)
|
|
|
|
if self.use_get:
|
|
return loading.load_on_ident(q, ident_key)
|
|
|
|
if self.parent_property.order_by:
|
|
q = q.order_by(*util.to_list(self.parent_property.order_by))
|
|
|
|
for rev in self.parent_property._reverse_property:
|
|
# reverse props that are MANYTOONE are loading *this*
|
|
# object from get(), so don't need to eager out to those.
|
|
if rev.direction is interfaces.MANYTOONE and \
|
|
rev._use_get and \
|
|
not isinstance(rev.strategy, LazyLoader):
|
|
q = q.options(strategy_options.Load(rev.parent).lazyload(rev.key))
|
|
|
|
lazy_clause = self.lazy_clause(state, passive=passive)
|
|
|
|
if pending:
|
|
bind_values = sql_util.bind_values(lazy_clause)
|
|
if None in bind_values:
|
|
return None
|
|
|
|
q = q.filter(lazy_clause)
|
|
|
|
|
|
result = q.all()
|
|
if self.uselist:
|
|
return result
|
|
else:
|
|
l = len(result)
|
|
if l:
|
|
if l > 1:
|
|
util.warn(
|
|
"Multiple rows returned with "
|
|
"uselist=False for lazily-loaded attribute '%s' "
|
|
% self.parent_property)
|
|
|
|
return result[0]
|
|
else:
|
|
return None
|
|
|
|
def create_row_processor(self, context, path, loadopt,
|
|
mapper, row, adapter):
|
|
key = self.key
|
|
if not self.is_class_level:
|
|
# we are not the primary manager for this attribute
|
|
# on this class - set up a
|
|
# per-instance lazyloader, which will override the
|
|
# class-level behavior.
|
|
# this currently only happens when using a
|
|
# "lazyload" option on a "no load"
|
|
# attribute - "eager" attributes always have a
|
|
# class-level lazyloader installed.
|
|
set_lazy_callable = InstanceState._row_processor(
|
|
mapper.class_manager,
|
|
LoadLazyAttribute(key), key)
|
|
|
|
return set_lazy_callable, None, None
|
|
else:
|
|
def reset_for_lazy_callable(state, dict_, row):
|
|
# we are the primary manager for this attribute on
|
|
# this class - reset its
|
|
# per-instance attribute state, so that the class-level
|
|
# lazy loader is
|
|
# executed when next referenced on this instance.
|
|
# this is needed in
|
|
# populate_existing() types of scenarios to reset
|
|
# any existing state.
|
|
state._reset(dict_, key)
|
|
|
|
return reset_for_lazy_callable, None, None
|
|
|
|
|
|
|
|
class LoadLazyAttribute(object):
|
|
"""serializable loader object used by LazyLoader"""
|
|
|
|
def __init__(self, key):
|
|
self.key = key
|
|
|
|
def __call__(self, state, passive=attributes.PASSIVE_OFF):
|
|
key = self.key
|
|
instance_mapper = state.manager.mapper
|
|
prop = instance_mapper._props[key]
|
|
strategy = prop._strategies[LazyLoader]
|
|
|
|
return strategy._load_for_state(state, passive)
|
|
|
|
|
|
@properties.RelationshipProperty.strategy_for(lazy="immediate")
|
|
class ImmediateLoader(AbstractRelationshipLoader):
|
|
def init_class_attribute(self, mapper):
|
|
self.parent_property.\
|
|
_get_strategy_by_cls(LazyLoader).\
|
|
init_class_attribute(mapper)
|
|
|
|
def setup_query(self, context, entity,
|
|
path, loadopt, adapter, column_collection=None,
|
|
parentmapper=None, **kwargs):
|
|
pass
|
|
|
|
def create_row_processor(self, context, path, loadopt,
|
|
mapper, row, adapter):
|
|
def load_immediate(state, dict_, row):
|
|
state.get_impl(self.key).get(state, dict_)
|
|
|
|
return None, None, load_immediate
|
|
|
|
|
|
@log.class_logger
|
|
@properties.RelationshipProperty.strategy_for(lazy="subquery")
|
|
class SubqueryLoader(AbstractRelationshipLoader):
|
|
def __init__(self, parent):
|
|
super(SubqueryLoader, self).__init__(parent)
|
|
self.join_depth = self.parent_property.join_depth
|
|
|
|
def init_class_attribute(self, mapper):
|
|
self.parent_property.\
|
|
_get_strategy_by_cls(LazyLoader).\
|
|
init_class_attribute(mapper)
|
|
|
|
def setup_query(self, context, entity,
|
|
path, loadopt, adapter,
|
|
column_collection=None,
|
|
parentmapper=None, **kwargs):
|
|
|
|
if not context.query._enable_eagerloads:
|
|
return
|
|
|
|
path = path[self.parent_property]
|
|
|
|
# build up a path indicating the path from the leftmost
|
|
# entity to the thing we're subquery loading.
|
|
with_poly_info = path.get(context.attributes,
|
|
"path_with_polymorphic", None)
|
|
if with_poly_info is not None:
|
|
effective_entity = with_poly_info.entity
|
|
else:
|
|
effective_entity = self.mapper
|
|
|
|
subq_path = context.attributes.get(('subquery_path', None),
|
|
orm_util.PathRegistry.root)
|
|
|
|
subq_path = subq_path + path
|
|
|
|
# if not via query option, check for
|
|
# a cycle
|
|
if not path.contains(context.attributes, "loader"):
|
|
if self.join_depth:
|
|
if path.length / 2 > self.join_depth:
|
|
return
|
|
elif subq_path.contains_mapper(self.mapper):
|
|
return
|
|
|
|
subq_mapper, leftmost_mapper, leftmost_attr, leftmost_relationship = \
|
|
self._get_leftmost(subq_path)
|
|
|
|
orig_query = context.attributes.get(
|
|
("orig_query", SubqueryLoader),
|
|
context.query)
|
|
|
|
# generate a new Query from the original, then
|
|
# produce a subquery from it.
|
|
left_alias = self._generate_from_original_query(
|
|
orig_query, leftmost_mapper,
|
|
leftmost_attr, leftmost_relationship,
|
|
entity.mapper
|
|
)
|
|
|
|
# generate another Query that will join the
|
|
# left alias to the target relationships.
|
|
# basically doing a longhand
|
|
# "from_self()". (from_self() itself not quite industrial
|
|
# strength enough for all contingencies...but very close)
|
|
q = orig_query.session.query(effective_entity)
|
|
q._attributes = {
|
|
("orig_query", SubqueryLoader): orig_query,
|
|
('subquery_path', None): subq_path
|
|
}
|
|
q = q._enable_single_crit(False)
|
|
|
|
to_join, local_attr, parent_alias = \
|
|
self._prep_for_joins(left_alias, subq_path)
|
|
q = q.order_by(*local_attr)
|
|
q = q.add_columns(*local_attr)
|
|
|
|
q = self._apply_joins(q, to_join, left_alias,
|
|
parent_alias, effective_entity)
|
|
|
|
q = self._setup_options(q, subq_path, orig_query, effective_entity)
|
|
q = self._setup_outermost_orderby(q)
|
|
|
|
# add new query to attributes to be picked up
|
|
# by create_row_processor
|
|
path.set(context.attributes, "subquery", q)
|
|
|
|
def _get_leftmost(self, subq_path):
|
|
subq_path = subq_path.path
|
|
subq_mapper = orm_util._class_to_mapper(subq_path[0])
|
|
|
|
# determine attributes of the leftmost mapper
|
|
if self.parent.isa(subq_mapper) and self.parent_property is subq_path[1]:
|
|
leftmost_mapper, leftmost_prop = \
|
|
self.parent, self.parent_property
|
|
else:
|
|
leftmost_mapper, leftmost_prop = \
|
|
subq_mapper, \
|
|
subq_path[1]
|
|
|
|
leftmost_cols = leftmost_prop.local_columns
|
|
|
|
leftmost_attr = [
|
|
leftmost_mapper._columntoproperty[c].class_attribute
|
|
for c in leftmost_cols
|
|
]
|
|
return subq_mapper, leftmost_mapper, leftmost_attr, leftmost_prop
|
|
|
|
def _generate_from_original_query(self,
|
|
orig_query, leftmost_mapper,
|
|
leftmost_attr, leftmost_relationship,
|
|
entity_mapper
|
|
):
|
|
# reformat the original query
|
|
# to look only for significant columns
|
|
q = orig_query._clone().correlate(None)
|
|
|
|
# set a real "from" if not present, as this is more
|
|
# accurate than just going off of the column expression
|
|
if not q._from_obj and entity_mapper.isa(leftmost_mapper):
|
|
q._set_select_from([entity_mapper], False)
|
|
|
|
target_cols = q._adapt_col_list(leftmost_attr)
|
|
|
|
# select from the identity columns of the outer
|
|
q._set_entities(target_cols)
|
|
|
|
distinct_target_key = leftmost_relationship.distinct_target_key
|
|
|
|
if distinct_target_key is True:
|
|
q._distinct = True
|
|
elif distinct_target_key is None:
|
|
# if target_cols refer to a non-primary key or only
|
|
# part of a composite primary key, set the q as distinct
|
|
for t in set(c.table for c in target_cols):
|
|
if not set(target_cols).issuperset(t.primary_key):
|
|
q._distinct = True
|
|
break
|
|
|
|
if q._order_by is False:
|
|
q._order_by = leftmost_mapper.order_by
|
|
|
|
# don't need ORDER BY if no limit/offset
|
|
if q._limit is None and q._offset is None:
|
|
q._order_by = None
|
|
|
|
# the original query now becomes a subquery
|
|
# which we'll join onto.
|
|
|
|
embed_q = q.with_labels().subquery()
|
|
left_alias = orm_util.AliasedClass(leftmost_mapper, embed_q,
|
|
use_mapper_path=True)
|
|
return left_alias
|
|
|
|
def _prep_for_joins(self, left_alias, subq_path):
|
|
# figure out what's being joined. a.k.a. the fun part
|
|
to_join = []
|
|
pairs = list(subq_path.pairs())
|
|
|
|
for i, (mapper, prop) in enumerate(pairs):
|
|
if i > 0:
|
|
# look at the previous mapper in the chain -
|
|
# if it is as or more specific than this prop's
|
|
# mapper, use that instead.
|
|
# note we have an assumption here that
|
|
# the non-first element is always going to be a mapper,
|
|
# not an AliasedClass
|
|
|
|
prev_mapper = pairs[i - 1][1].mapper
|
|
to_append = prev_mapper if prev_mapper.isa(mapper) else mapper
|
|
else:
|
|
to_append = mapper
|
|
|
|
to_join.append((to_append, prop.key))
|
|
|
|
# determine the immediate parent class we are joining from,
|
|
# which needs to be aliased.
|
|
if len(to_join) > 1:
|
|
info = inspect(to_join[-1][0])
|
|
|
|
if len(to_join) < 2:
|
|
# in the case of a one level eager load, this is the
|
|
# leftmost "left_alias".
|
|
parent_alias = left_alias
|
|
elif info.mapper.isa(self.parent):
|
|
# In the case of multiple levels, retrieve
|
|
# it from subq_path[-2]. This is the same as self.parent
|
|
# in the vast majority of cases, and [ticket:2014]
|
|
# illustrates a case where sub_path[-2] is a subclass
|
|
# of self.parent
|
|
parent_alias = orm_util.AliasedClass(to_join[-1][0],
|
|
use_mapper_path=True)
|
|
else:
|
|
# if of_type() were used leading to this relationship,
|
|
# self.parent is more specific than subq_path[-2]
|
|
parent_alias = orm_util.AliasedClass(self.parent,
|
|
use_mapper_path=True)
|
|
|
|
local_cols = self.parent_property.local_columns
|
|
|
|
local_attr = [
|
|
getattr(parent_alias, self.parent._columntoproperty[c].key)
|
|
for c in local_cols
|
|
]
|
|
return to_join, local_attr, parent_alias
|
|
|
|
def _apply_joins(self, q, to_join, left_alias, parent_alias,
|
|
effective_entity):
|
|
for i, (mapper, key) in enumerate(to_join):
|
|
|
|
# we need to use query.join() as opposed to
|
|
# orm.join() here because of the
|
|
# rich behavior it brings when dealing with
|
|
# "with_polymorphic" mappers. "aliased"
|
|
# and "from_joinpoint" take care of most of
|
|
# the chaining and aliasing for us.
|
|
|
|
first = i == 0
|
|
middle = i < len(to_join) - 1
|
|
second_to_last = i == len(to_join) - 2
|
|
last = i == len(to_join) - 1
|
|
|
|
if first:
|
|
attr = getattr(left_alias, key)
|
|
if last and effective_entity is not self.mapper:
|
|
attr = attr.of_type(effective_entity)
|
|
else:
|
|
if last and effective_entity is not self.mapper:
|
|
attr = getattr(parent_alias, key).\
|
|
of_type(effective_entity)
|
|
else:
|
|
attr = key
|
|
|
|
if second_to_last:
|
|
q = q.join(parent_alias, attr, from_joinpoint=True)
|
|
else:
|
|
q = q.join(attr, aliased=middle, from_joinpoint=True)
|
|
return q
|
|
|
|
def _setup_options(self, q, subq_path, orig_query, effective_entity):
|
|
# propagate loader options etc. to the new query.
|
|
# these will fire relative to subq_path.
|
|
q = q._with_current_path(subq_path)
|
|
q = q._conditional_options(*orig_query._with_options)
|
|
if orig_query._populate_existing:
|
|
q._populate_existing = orig_query._populate_existing
|
|
|
|
return q
|
|
|
|
def _setup_outermost_orderby(self, q):
|
|
if self.parent_property.order_by:
|
|
# if there's an ORDER BY, alias it the same
|
|
# way joinedloader does, but we have to pull out
|
|
# the "eagerjoin" from the query.
|
|
# this really only picks up the "secondary" table
|
|
# right now.
|
|
eagerjoin = q._from_obj[0]
|
|
eager_order_by = \
|
|
eagerjoin._target_adapter.\
|
|
copy_and_process(
|
|
util.to_list(
|
|
self.parent_property.order_by
|
|
)
|
|
)
|
|
q = q.order_by(*eager_order_by)
|
|
return q
|
|
|
|
class _SubqCollections(object):
|
|
"""Given a :class:`.Query` used to emit the "subquery load",
|
|
provide a load interface that executes the query at the
|
|
first moment a value is needed.
|
|
|
|
"""
|
|
_data = None
|
|
|
|
def __init__(self, subq):
|
|
self.subq = subq
|
|
|
|
def get(self, key, default):
|
|
if self._data is None:
|
|
self._load()
|
|
return self._data.get(key, default)
|
|
|
|
def _load(self):
|
|
self._data = dict(
|
|
(k, [vv[0] for vv in v])
|
|
for k, v in itertools.groupby(
|
|
self.subq,
|
|
lambda x: x[1:]
|
|
)
|
|
)
|
|
|
|
def loader(self, state, dict_, row):
|
|
if self._data is None:
|
|
self._load()
|
|
|
|
def create_row_processor(self, context, path, loadopt,
|
|
mapper, row, adapter):
|
|
if not self.parent.class_manager[self.key].impl.supports_population:
|
|
raise sa_exc.InvalidRequestError(
|
|
"'%s' does not support object "
|
|
"population - eager loading cannot be applied." %
|
|
self)
|
|
|
|
path = path[self.parent_property]
|
|
|
|
subq = path.get(context.attributes, 'subquery')
|
|
|
|
if subq is None:
|
|
return None, None, None
|
|
|
|
local_cols = self.parent_property.local_columns
|
|
|
|
# cache the loaded collections in the context
|
|
# so that inheriting mappers don't re-load when they
|
|
# call upon create_row_processor again
|
|
collections = path.get(context.attributes, "collections")
|
|
if collections is None:
|
|
collections = self._SubqCollections(subq)
|
|
path.set(context.attributes, 'collections', collections)
|
|
|
|
if adapter:
|
|
local_cols = [adapter.columns[c] for c in local_cols]
|
|
|
|
if self.uselist:
|
|
return self._create_collection_loader(collections, local_cols)
|
|
else:
|
|
return self._create_scalar_loader(collections, local_cols)
|
|
|
|
def _create_collection_loader(self, collections, local_cols):
|
|
def load_collection_from_subq(state, dict_, row):
|
|
collection = collections.get(
|
|
tuple([row[col] for col in local_cols]),
|
|
()
|
|
)
|
|
state.get_impl(self.key).\
|
|
set_committed_value(state, dict_, collection)
|
|
|
|
return load_collection_from_subq, None, None, collections.loader
|
|
|
|
def _create_scalar_loader(self, collections, local_cols):
|
|
def load_scalar_from_subq(state, dict_, row):
|
|
collection = collections.get(
|
|
tuple([row[col] for col in local_cols]),
|
|
(None,)
|
|
)
|
|
if len(collection) > 1:
|
|
util.warn(
|
|
"Multiple rows returned with "
|
|
"uselist=False for eagerly-loaded attribute '%s' "
|
|
% self)
|
|
|
|
scalar = collection[0]
|
|
state.get_impl(self.key).\
|
|
set_committed_value(state, dict_, scalar)
|
|
|
|
return load_scalar_from_subq, None, None, collections.loader
|
|
|
|
|
|
|
|
@log.class_logger
|
|
@properties.RelationshipProperty.strategy_for(lazy="joined")
|
|
@properties.RelationshipProperty.strategy_for(lazy=False)
|
|
class JoinedLoader(AbstractRelationshipLoader):
|
|
"""Provide loading behavior for a :class:`.RelationshipProperty`
|
|
using joined eager loading.
|
|
|
|
"""
|
|
def __init__(self, parent):
|
|
super(JoinedLoader, self).__init__(parent)
|
|
self.join_depth = self.parent_property.join_depth
|
|
|
|
def init_class_attribute(self, mapper):
|
|
self.parent_property.\
|
|
_get_strategy_by_cls(LazyLoader).init_class_attribute(mapper)
|
|
|
|
def setup_query(self, context, entity, path, loadopt, adapter, \
|
|
column_collection=None, parentmapper=None,
|
|
**kwargs):
|
|
"""Add a left outer join to the statement thats being constructed."""
|
|
|
|
if not context.query._enable_eagerloads:
|
|
return
|
|
|
|
path = path[self.parent_property]
|
|
|
|
with_polymorphic = None
|
|
|
|
user_defined_adapter = self._init_user_defined_eager_proc(
|
|
loadopt, context) if loadopt else False
|
|
|
|
if user_defined_adapter is not False:
|
|
clauses, adapter, add_to_collection = \
|
|
self._setup_query_on_user_defined_adapter(
|
|
context, entity, path, adapter,
|
|
user_defined_adapter
|
|
)
|
|
else:
|
|
# if not via query option, check for
|
|
# a cycle
|
|
if not path.contains(context.attributes, "loader"):
|
|
if self.join_depth:
|
|
if path.length / 2 > self.join_depth:
|
|
return
|
|
elif path.contains_mapper(self.mapper):
|
|
return
|
|
|
|
clauses, adapter, add_to_collection = self._generate_row_adapter(
|
|
context, entity, path, loadopt, adapter,
|
|
column_collection, parentmapper
|
|
)
|
|
|
|
with_poly_info = path.get(
|
|
context.attributes,
|
|
"path_with_polymorphic",
|
|
None
|
|
)
|
|
if with_poly_info is not None:
|
|
with_polymorphic = with_poly_info.with_polymorphic_mappers
|
|
else:
|
|
with_polymorphic = None
|
|
|
|
path = path[self.mapper]
|
|
|
|
for value in self.mapper._iterate_polymorphic_properties(
|
|
mappers=with_polymorphic):
|
|
value.setup(
|
|
context,
|
|
entity,
|
|
path,
|
|
clauses,
|
|
parentmapper=self.mapper,
|
|
column_collection=add_to_collection)
|
|
|
|
if with_poly_info is not None and \
|
|
None in set(context.secondary_columns):
|
|
raise sa_exc.InvalidRequestError(
|
|
"Detected unaliased columns when generating joined "
|
|
"load. Make sure to use aliased=True or flat=True "
|
|
"when using joined loading with with_polymorphic()."
|
|
)
|
|
|
|
def _init_user_defined_eager_proc(self, loadopt, context):
|
|
|
|
# check if the opt applies at all
|
|
if "eager_from_alias" not in loadopt.local_opts:
|
|
# nope
|
|
return False
|
|
|
|
path = loadopt.path.parent
|
|
|
|
# the option applies. check if the "user_defined_eager_row_processor"
|
|
# has been built up.
|
|
adapter = path.get(context.attributes,
|
|
"user_defined_eager_row_processor", False)
|
|
if adapter is not False:
|
|
# just return it
|
|
return adapter
|
|
|
|
# otherwise figure it out.
|
|
alias = loadopt.local_opts["eager_from_alias"]
|
|
|
|
root_mapper, prop = path[-2:]
|
|
|
|
#from .mapper import Mapper
|
|
#from .interfaces import MapperProperty
|
|
#assert isinstance(root_mapper, Mapper)
|
|
#assert isinstance(prop, MapperProperty)
|
|
|
|
if alias is not None:
|
|
if isinstance(alias, str):
|
|
alias = prop.target.alias(alias)
|
|
adapter = sql_util.ColumnAdapter(alias,
|
|
equivalents=prop.mapper._equivalent_columns)
|
|
else:
|
|
if path.contains(context.attributes, "path_with_polymorphic"):
|
|
with_poly_info = path.get(context.attributes,
|
|
"path_with_polymorphic")
|
|
adapter = orm_util.ORMAdapter(
|
|
with_poly_info.entity,
|
|
equivalents=prop.mapper._equivalent_columns)
|
|
else:
|
|
adapter = context.query._polymorphic_adapters.get(prop.mapper, None)
|
|
path.set(context.attributes,
|
|
"user_defined_eager_row_processor",
|
|
adapter)
|
|
|
|
return adapter
|
|
|
|
def _setup_query_on_user_defined_adapter(self, context, entity,
|
|
path, adapter, user_defined_adapter):
|
|
|
|
# apply some more wrapping to the "user defined adapter"
|
|
# if we are setting up the query for SQL render.
|
|
adapter = entity._get_entity_clauses(context.query, context)
|
|
|
|
if adapter and user_defined_adapter:
|
|
user_defined_adapter = user_defined_adapter.wrap(adapter)
|
|
path.set(context.attributes, "user_defined_eager_row_processor",
|
|
user_defined_adapter)
|
|
elif adapter:
|
|
user_defined_adapter = adapter
|
|
path.set(context.attributes, "user_defined_eager_row_processor",
|
|
user_defined_adapter)
|
|
|
|
add_to_collection = context.primary_columns
|
|
return user_defined_adapter, adapter, add_to_collection
|
|
|
|
def _generate_row_adapter(self,
|
|
context, entity, path, loadopt, adapter,
|
|
column_collection, parentmapper
|
|
):
|
|
with_poly_info = path.get(
|
|
context.attributes,
|
|
"path_with_polymorphic",
|
|
None
|
|
)
|
|
if with_poly_info:
|
|
to_adapt = with_poly_info.entity
|
|
else:
|
|
to_adapt = orm_util.AliasedClass(self.mapper,
|
|
flat=True,
|
|
use_mapper_path=True)
|
|
clauses = orm_util.ORMAdapter(
|
|
to_adapt,
|
|
equivalents=self.mapper._equivalent_columns,
|
|
adapt_required=True)
|
|
assert clauses.aliased_class is not None
|
|
|
|
if self.parent_property.direction != interfaces.MANYTOONE:
|
|
context.multi_row_eager_loaders = True
|
|
|
|
innerjoin = (
|
|
loadopt.local_opts.get(
|
|
'innerjoin', self.parent_property.innerjoin)
|
|
if loadopt is not None
|
|
else self.parent_property.innerjoin
|
|
)
|
|
|
|
context.create_eager_joins.append(
|
|
(self._create_eager_join, context,
|
|
entity, path, adapter,
|
|
parentmapper, clauses, innerjoin)
|
|
)
|
|
|
|
add_to_collection = context.secondary_columns
|
|
path.set(context.attributes, "eager_row_processor", clauses)
|
|
|
|
return clauses, adapter, add_to_collection
|
|
|
|
def _create_eager_join(self, context, entity,
|
|
path, adapter, parentmapper,
|
|
clauses, innerjoin):
|
|
|
|
if parentmapper is None:
|
|
localparent = entity.mapper
|
|
else:
|
|
localparent = parentmapper
|
|
|
|
# whether or not the Query will wrap the selectable in a subquery,
|
|
# and then attach eager load joins to that (i.e., in the case of
|
|
# LIMIT/OFFSET etc.)
|
|
should_nest_selectable = context.multi_row_eager_loaders and \
|
|
context.query._should_nest_selectable
|
|
|
|
entity_key = None
|
|
|
|
if entity not in context.eager_joins and \
|
|
not should_nest_selectable and \
|
|
context.from_clause:
|
|
index, clause = \
|
|
sql_util.find_join_source(
|
|
context.from_clause, entity.selectable)
|
|
if clause is not None:
|
|
# join to an existing FROM clause on the query.
|
|
# key it to its list index in the eager_joins dict.
|
|
# Query._compile_context will adapt as needed and
|
|
# append to the FROM clause of the select().
|
|
entity_key, default_towrap = index, clause
|
|
|
|
if entity_key is None:
|
|
entity_key, default_towrap = entity, entity.selectable
|
|
|
|
towrap = context.eager_joins.setdefault(entity_key, default_towrap)
|
|
|
|
if adapter:
|
|
if getattr(adapter, 'aliased_class', None):
|
|
onclause = getattr(
|
|
adapter.aliased_class, self.key,
|
|
self.parent_property)
|
|
else:
|
|
onclause = getattr(
|
|
orm_util.AliasedClass(
|
|
self.parent,
|
|
adapter.selectable,
|
|
use_mapper_path=True
|
|
),
|
|
self.key, self.parent_property
|
|
)
|
|
|
|
else:
|
|
onclause = self.parent_property
|
|
|
|
assert clauses.aliased_class is not None
|
|
|
|
join_to_outer = innerjoin and isinstance(towrap, sql.Join) and towrap.isouter
|
|
|
|
if join_to_outer and innerjoin == 'nested':
|
|
inner = orm_util.join(
|
|
towrap.right,
|
|
clauses.aliased_class,
|
|
onclause,
|
|
isouter=False
|
|
)
|
|
|
|
eagerjoin = orm_util.join(
|
|
towrap.left,
|
|
inner,
|
|
towrap.onclause,
|
|
isouter=True
|
|
)
|
|
eagerjoin._target_adapter = inner._target_adapter
|
|
else:
|
|
if join_to_outer:
|
|
innerjoin = False
|
|
eagerjoin = orm_util.join(
|
|
towrap,
|
|
clauses.aliased_class,
|
|
onclause,
|
|
isouter=not innerjoin
|
|
)
|
|
context.eager_joins[entity_key] = eagerjoin
|
|
|
|
# send a hint to the Query as to where it may "splice" this join
|
|
eagerjoin.stop_on = entity.selectable
|
|
|
|
if self.parent_property.secondary is None and \
|
|
not parentmapper:
|
|
# for parentclause that is the non-eager end of the join,
|
|
# ensure all the parent cols in the primaryjoin are actually
|
|
# in the
|
|
# columns clause (i.e. are not deferred), so that aliasing applied
|
|
# by the Query propagates those columns outward.
|
|
# This has the effect
|
|
# of "undefering" those columns.
|
|
for col in sql_util._find_columns(
|
|
self.parent_property.primaryjoin):
|
|
if localparent.mapped_table.c.contains_column(col):
|
|
if adapter:
|
|
col = adapter.columns[col]
|
|
context.primary_columns.append(col)
|
|
|
|
if self.parent_property.order_by:
|
|
context.eager_order_by += \
|
|
eagerjoin._target_adapter.\
|
|
copy_and_process(
|
|
util.to_list(
|
|
self.parent_property.order_by
|
|
)
|
|
)
|
|
|
|
def _create_eager_adapter(self, context, row, adapter, path, loadopt):
|
|
user_defined_adapter = self._init_user_defined_eager_proc(
|
|
loadopt, context) if loadopt else False
|
|
|
|
if user_defined_adapter is not False:
|
|
decorator = user_defined_adapter
|
|
# user defined eagerloads are part of the "primary"
|
|
# portion of the load.
|
|
# the adapters applied to the Query should be honored.
|
|
if context.adapter and decorator:
|
|
decorator = decorator.wrap(context.adapter)
|
|
elif context.adapter:
|
|
decorator = context.adapter
|
|
else:
|
|
decorator = path.get(context.attributes, "eager_row_processor")
|
|
if decorator is None:
|
|
return False
|
|
|
|
try:
|
|
self.mapper.identity_key_from_row(row, decorator)
|
|
return decorator
|
|
except KeyError:
|
|
# no identity key - dont return a row
|
|
# processor, will cause a degrade to lazy
|
|
return False
|
|
|
|
def create_row_processor(self, context, path, loadopt, mapper, row, adapter):
|
|
if not self.parent.class_manager[self.key].impl.supports_population:
|
|
raise sa_exc.InvalidRequestError(
|
|
"'%s' does not support object "
|
|
"population - eager loading cannot be applied." %
|
|
self)
|
|
|
|
our_path = path[self.parent_property]
|
|
|
|
eager_adapter = self._create_eager_adapter(
|
|
context,
|
|
row,
|
|
adapter, our_path, loadopt)
|
|
|
|
if eager_adapter is not False:
|
|
key = self.key
|
|
|
|
_instance = loading.instance_processor(
|
|
self.mapper,
|
|
context,
|
|
our_path[self.mapper],
|
|
eager_adapter)
|
|
|
|
if not self.uselist:
|
|
return self._create_scalar_loader(context, key, _instance)
|
|
else:
|
|
return self._create_collection_loader(context, key, _instance)
|
|
else:
|
|
return self.parent_property.\
|
|
_get_strategy_by_cls(LazyLoader).\
|
|
create_row_processor(
|
|
context, path, loadopt,
|
|
mapper, row, adapter)
|
|
|
|
def _create_collection_loader(self, context, key, _instance):
|
|
def load_collection_from_joined_new_row(state, dict_, row):
|
|
collection = attributes.init_state_collection(
|
|
state, dict_, key)
|
|
result_list = util.UniqueAppender(collection,
|
|
'append_without_event')
|
|
context.attributes[(state, key)] = result_list
|
|
_instance(row, result_list)
|
|
|
|
def load_collection_from_joined_existing_row(state, dict_, row):
|
|
if (state, key) in context.attributes:
|
|
result_list = context.attributes[(state, key)]
|
|
else:
|
|
# appender_key can be absent from context.attributes
|
|
# with isnew=False when self-referential eager loading
|
|
# is used; the same instance may be present in two
|
|
# distinct sets of result columns
|
|
collection = attributes.init_state_collection(state,
|
|
dict_, key)
|
|
result_list = util.UniqueAppender(
|
|
collection,
|
|
'append_without_event')
|
|
context.attributes[(state, key)] = result_list
|
|
_instance(row, result_list)
|
|
|
|
def load_collection_from_joined_exec(state, dict_, row):
|
|
_instance(row, None)
|
|
|
|
return load_collection_from_joined_new_row, \
|
|
load_collection_from_joined_existing_row, \
|
|
None, load_collection_from_joined_exec
|
|
|
|
def _create_scalar_loader(self, context, key, _instance):
|
|
def load_scalar_from_joined_new_row(state, dict_, row):
|
|
# set a scalar object instance directly on the parent
|
|
# object, bypassing InstrumentedAttribute event handlers.
|
|
dict_[key] = _instance(row, None)
|
|
|
|
def load_scalar_from_joined_existing_row(state, dict_, row):
|
|
# call _instance on the row, even though the object has
|
|
# been created, so that we further descend into properties
|
|
existing = _instance(row, None)
|
|
if existing is not None \
|
|
and key in dict_ \
|
|
and existing is not dict_[key]:
|
|
util.warn(
|
|
"Multiple rows returned with "
|
|
"uselist=False for eagerly-loaded attribute '%s' "
|
|
% self)
|
|
|
|
def load_scalar_from_joined_exec(state, dict_, row):
|
|
_instance(row, None)
|
|
|
|
return load_scalar_from_joined_new_row, \
|
|
load_scalar_from_joined_existing_row, \
|
|
None, load_scalar_from_joined_exec
|
|
|
|
|
|
|
|
def single_parent_validator(desc, prop):
|
|
def _do_check(state, value, oldvalue, initiator):
|
|
if value is not None and initiator.key == prop.key:
|
|
hasparent = initiator.hasparent(attributes.instance_state(value))
|
|
if hasparent and oldvalue is not value:
|
|
raise sa_exc.InvalidRequestError(
|
|
"Instance %s is already associated with an instance "
|
|
"of %s via its %s attribute, and is only allowed a "
|
|
"single parent." %
|
|
(orm_util.instance_str(value), state.class_, prop)
|
|
)
|
|
return value
|
|
|
|
def append(state, value, initiator):
|
|
return _do_check(state, value, None, initiator)
|
|
|
|
def set_(state, value, oldvalue, initiator):
|
|
return _do_check(state, value, oldvalue, initiator)
|
|
|
|
event.listen(desc, 'append', append, raw=True, retval=True,
|
|
active_history=True)
|
|
event.listen(desc, 'set', set_, raw=True, retval=True,
|
|
active_history=True)
|