607 lines
21 KiB
Python
607 lines
21 KiB
Python
# orm/loading.py
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# Copyright (C) 2005-2013 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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"""private module containing functions used to convert database
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rows into object instances and associated state.
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the functions here are called primarily by Query, Mapper,
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as well as some of the attribute loading strategies.
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"""
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from __future__ import absolute_import
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from .. import util
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from . import attributes, exc as orm_exc, state as statelib
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from .interfaces import EXT_CONTINUE
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from ..sql import util as sql_util
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from .util import _none_set, state_str
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from .. import exc as sa_exc
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sessionlib = util.importlater("sqlalchemy.orm", "session")
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_new_runid = util.counter()
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def instances(query, cursor, context):
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"""Return an ORM result as an iterator."""
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session = query.session
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context.runid = _new_runid()
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filter_fns = [ent.filter_fn
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for ent in query._entities]
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filtered = id in filter_fns
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single_entity = filtered and len(query._entities) == 1
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if filtered:
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if single_entity:
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filter_fn = id
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else:
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def filter_fn(row):
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return tuple(fn(x) for x, fn in zip(row, filter_fns))
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custom_rows = single_entity and \
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query._entities[0].mapper.dispatch.append_result
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(process, labels) = \
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zip(*[
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query_entity.row_processor(query,
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context, custom_rows)
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for query_entity in query._entities
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])
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while True:
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context.progress = {}
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context.partials = {}
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if query._yield_per:
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fetch = cursor.fetchmany(query._yield_per)
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if not fetch:
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break
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else:
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fetch = cursor.fetchall()
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if custom_rows:
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rows = []
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for row in fetch:
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process[0](row, rows)
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elif single_entity:
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rows = [process[0](row, None) for row in fetch]
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else:
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rows = [util.KeyedTuple([proc(row, None) for proc in process],
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labels) for row in fetch]
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if filtered:
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rows = util.unique_list(rows, filter_fn)
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if context.refresh_state and query._only_load_props \
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and context.refresh_state in context.progress:
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context.refresh_state._commit(
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context.refresh_state.dict, query._only_load_props)
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context.progress.pop(context.refresh_state)
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statelib.InstanceState._commit_all_states(
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context.progress.items(),
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session.identity_map
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)
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for state, (dict_, attrs) in context.partials.iteritems():
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state._commit(dict_, attrs)
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for row in rows:
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yield row
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if not query._yield_per:
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break
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def merge_result(query, iterator, load=True):
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"""Merge a result into this :class:`.Query` object's Session."""
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from . import query as querylib
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session = query.session
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if load:
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# flush current contents if we expect to load data
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session._autoflush()
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autoflush = session.autoflush
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try:
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session.autoflush = False
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single_entity = len(query._entities) == 1
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if single_entity:
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if isinstance(query._entities[0], querylib._MapperEntity):
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result = [session._merge(
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attributes.instance_state(instance),
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attributes.instance_dict(instance),
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load=load, _recursive={})
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for instance in iterator]
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else:
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result = list(iterator)
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else:
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mapped_entities = [i for i, e in enumerate(query._entities)
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if isinstance(e, querylib._MapperEntity)]
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result = []
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keys = [ent._label_name for ent in query._entities]
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for row in iterator:
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newrow = list(row)
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for i in mapped_entities:
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if newrow[i] is not None:
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newrow[i] = session._merge(
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attributes.instance_state(newrow[i]),
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attributes.instance_dict(newrow[i]),
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load=load, _recursive={})
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result.append(util.KeyedTuple(newrow, keys))
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return iter(result)
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finally:
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session.autoflush = autoflush
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def get_from_identity(session, key, passive):
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"""Look up the given key in the given session's identity map,
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check the object for expired state if found.
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"""
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instance = session.identity_map.get(key)
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if instance is not None:
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state = attributes.instance_state(instance)
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# expired - ensure it still exists
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if state.expired:
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if not passive & attributes.SQL_OK:
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# TODO: no coverage here
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return attributes.PASSIVE_NO_RESULT
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elif not passive & attributes.RELATED_OBJECT_OK:
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# this mode is used within a flush and the instance's
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# expired state will be checked soon enough, if necessary
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return instance
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try:
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state(state, passive)
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except orm_exc.ObjectDeletedError:
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session._remove_newly_deleted([state])
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return None
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return instance
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else:
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return None
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def load_on_ident(query, key,
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refresh_state=None, lockmode=None,
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only_load_props=None):
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"""Load the given identity key from the database."""
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lockmode = lockmode or query._lockmode
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if key is not None:
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ident = key[1]
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else:
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ident = None
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if refresh_state is None:
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q = query._clone()
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q._get_condition()
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else:
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q = query._clone()
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if ident is not None:
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mapper = query._mapper_zero()
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(_get_clause, _get_params) = mapper._get_clause
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# None present in ident - turn those comparisons
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# into "IS NULL"
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if None in ident:
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nones = set([
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_get_params[col].key for col, value in
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zip(mapper.primary_key, ident) if value is None
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])
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_get_clause = sql_util.adapt_criterion_to_null(
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_get_clause, nones)
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_get_clause = q._adapt_clause(_get_clause, True, False)
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q._criterion = _get_clause
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params = dict([
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(_get_params[primary_key].key, id_val)
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for id_val, primary_key in zip(ident, mapper.primary_key)
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])
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q._params = params
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if lockmode is not None:
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q._lockmode = lockmode
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q._get_options(
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populate_existing=bool(refresh_state),
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version_check=(lockmode is not None),
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only_load_props=only_load_props,
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refresh_state=refresh_state)
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q._order_by = None
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try:
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return q.one()
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except orm_exc.NoResultFound:
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return None
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def instance_processor(mapper, context, path, adapter,
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polymorphic_from=None,
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only_load_props=None,
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refresh_state=None,
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polymorphic_discriminator=None):
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"""Produce a mapper level row processor callable
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which processes rows into mapped instances."""
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# note that this method, most of which exists in a closure
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# called _instance(), resists being broken out, as
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# attempts to do so tend to add significant function
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# call overhead. _instance() is the most
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# performance-critical section in the whole ORM.
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pk_cols = mapper.primary_key
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if polymorphic_from or refresh_state:
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polymorphic_on = None
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else:
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if polymorphic_discriminator is not None:
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polymorphic_on = polymorphic_discriminator
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else:
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polymorphic_on = mapper.polymorphic_on
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polymorphic_instances = util.PopulateDict(
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_configure_subclass_mapper(
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mapper,
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context, path, adapter)
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)
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version_id_col = mapper.version_id_col
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if adapter:
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pk_cols = [adapter.columns[c] for c in pk_cols]
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if polymorphic_on is not None:
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polymorphic_on = adapter.columns[polymorphic_on]
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if version_id_col is not None:
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version_id_col = adapter.columns[version_id_col]
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identity_class = mapper._identity_class
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new_populators = []
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existing_populators = []
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eager_populators = []
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load_path = context.query._current_path + path \
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if context.query._current_path.path \
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else path
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def populate_state(state, dict_, row, isnew, only_load_props):
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if isnew:
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if context.propagate_options:
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state.load_options = context.propagate_options
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if state.load_options:
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state.load_path = load_path
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if not new_populators:
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_populators(mapper, context, path, row, adapter,
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new_populators,
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existing_populators,
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eager_populators
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)
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if isnew:
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populators = new_populators
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else:
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populators = existing_populators
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if only_load_props is None:
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for key, populator in populators:
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populator(state, dict_, row)
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elif only_load_props:
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for key, populator in populators:
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if key in only_load_props:
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populator(state, dict_, row)
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session_identity_map = context.session.identity_map
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listeners = mapper.dispatch
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translate_row = listeners.translate_row or None
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create_instance = listeners.create_instance or None
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populate_instance = listeners.populate_instance or None
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append_result = listeners.append_result or None
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populate_existing = context.populate_existing or mapper.always_refresh
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invoke_all_eagers = context.invoke_all_eagers
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if mapper.allow_partial_pks:
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is_not_primary_key = _none_set.issuperset
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else:
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is_not_primary_key = _none_set.issubset
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def _instance(row, result):
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if not new_populators and invoke_all_eagers:
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_populators(mapper, context, path, row, adapter,
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new_populators,
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existing_populators,
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eager_populators
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)
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if translate_row:
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for fn in translate_row:
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ret = fn(mapper, context, row)
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if ret is not EXT_CONTINUE:
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row = ret
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break
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if polymorphic_on is not None:
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discriminator = row[polymorphic_on]
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if discriminator is not None:
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_instance = polymorphic_instances[discriminator]
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if _instance:
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return _instance(row, result)
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# determine identity key
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if refresh_state:
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identitykey = refresh_state.key
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if identitykey is None:
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# super-rare condition; a refresh is being called
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# on a non-instance-key instance; this is meant to only
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# occur within a flush()
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identitykey = mapper._identity_key_from_state(refresh_state)
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else:
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identitykey = (
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identity_class,
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tuple([row[column] for column in pk_cols])
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)
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instance = session_identity_map.get(identitykey)
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if instance is not None:
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state = attributes.instance_state(instance)
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dict_ = attributes.instance_dict(instance)
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isnew = state.runid != context.runid
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currentload = not isnew
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loaded_instance = False
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if not currentload and \
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version_id_col is not None and \
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context.version_check and \
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mapper._get_state_attr_by_column(
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state,
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dict_,
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mapper.version_id_col) != \
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row[version_id_col]:
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raise orm_exc.StaleDataError(
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"Instance '%s' has version id '%s' which "
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"does not match database-loaded version id '%s'."
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% (state_str(state),
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mapper._get_state_attr_by_column(
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state, dict_,
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mapper.version_id_col),
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row[version_id_col]))
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elif refresh_state:
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# out of band refresh_state detected (i.e. its not in the
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# session.identity_map) honor it anyway. this can happen
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# if a _get() occurs within save_obj(), such as
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# when eager_defaults is True.
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state = refresh_state
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instance = state.obj()
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dict_ = attributes.instance_dict(instance)
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isnew = state.runid != context.runid
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currentload = True
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loaded_instance = False
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else:
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# check for non-NULL values in the primary key columns,
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# else no entity is returned for the row
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if is_not_primary_key(identitykey[1]):
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return None
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isnew = True
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currentload = True
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loaded_instance = True
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if create_instance:
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for fn in create_instance:
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instance = fn(mapper, context,
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row, mapper.class_)
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if instance is not EXT_CONTINUE:
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manager = attributes.manager_of_class(
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instance.__class__)
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# TODO: if manager is None, raise a friendly error
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# about returning instances of unmapped types
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manager.setup_instance(instance)
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break
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else:
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instance = mapper.class_manager.new_instance()
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else:
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instance = mapper.class_manager.new_instance()
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dict_ = attributes.instance_dict(instance)
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state = attributes.instance_state(instance)
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state.key = identitykey
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# attach instance to session.
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state.session_id = context.session.hash_key
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session_identity_map.add(state)
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if currentload or populate_existing:
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# state is being fully loaded, so populate.
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# add to the "context.progress" collection.
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if isnew:
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state.runid = context.runid
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context.progress[state] = dict_
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if populate_instance:
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for fn in populate_instance:
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ret = fn(mapper, context, row, state,
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only_load_props=only_load_props,
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instancekey=identitykey, isnew=isnew)
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if ret is not EXT_CONTINUE:
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break
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else:
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populate_state(state, dict_, row, isnew, only_load_props)
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else:
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populate_state(state, dict_, row, isnew, only_load_props)
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if loaded_instance:
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state.manager.dispatch.load(state, context)
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elif isnew:
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state.manager.dispatch.refresh(state, context, only_load_props)
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elif state in context.partials or state.unloaded or eager_populators:
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# state is having a partial set of its attributes
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# refreshed. Populate those attributes,
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# and add to the "context.partials" collection.
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if state in context.partials:
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isnew = False
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(d_, attrs) = context.partials[state]
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else:
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isnew = True
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attrs = state.unloaded
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context.partials[state] = (dict_, attrs)
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if populate_instance:
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for fn in populate_instance:
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ret = fn(mapper, context, row, state,
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only_load_props=attrs,
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instancekey=identitykey, isnew=isnew)
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if ret is not EXT_CONTINUE:
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break
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else:
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populate_state(state, dict_, row, isnew, attrs)
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else:
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populate_state(state, dict_, row, isnew, attrs)
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for key, pop in eager_populators:
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if key not in state.unloaded:
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pop(state, dict_, row)
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if isnew:
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state.manager.dispatch.refresh(state, context, attrs)
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if result is not None:
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if append_result:
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for fn in append_result:
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if fn(mapper, context, row, state,
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result, instancekey=identitykey,
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isnew=isnew) is not EXT_CONTINUE:
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break
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else:
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result.append(instance)
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else:
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result.append(instance)
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return instance
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return _instance
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def _populators(mapper, context, path, row, adapter,
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new_populators, existing_populators, eager_populators):
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"""Produce a collection of attribute level row processor
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callables."""
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delayed_populators = []
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pops = (new_populators, existing_populators, delayed_populators,
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eager_populators)
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for prop in mapper._props.itervalues():
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for i, pop in enumerate(prop.create_row_processor(
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context,
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path,
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mapper, row, adapter)):
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if pop is not None:
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pops[i].append((prop.key, pop))
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if delayed_populators:
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new_populators.extend(delayed_populators)
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def _configure_subclass_mapper(mapper, context, path, adapter):
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"""Produce a mapper level row processor callable factory for mappers
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inheriting this one."""
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def configure_subclass_mapper(discriminator):
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try:
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sub_mapper = mapper.polymorphic_map[discriminator]
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except KeyError:
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raise AssertionError(
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"No such polymorphic_identity %r is defined" %
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discriminator)
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if sub_mapper is mapper:
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return None
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return instance_processor(
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sub_mapper,
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context,
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path,
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adapter,
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polymorphic_from=mapper)
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return configure_subclass_mapper
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def load_scalar_attributes(mapper, state, attribute_names):
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"""initiate a column-based attribute refresh operation."""
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#assert mapper is _state_mapper(state)
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session = sessionlib._state_session(state)
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if not session:
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raise orm_exc.DetachedInstanceError(
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"Instance %s is not bound to a Session; "
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"attribute refresh operation cannot proceed" %
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(state_str(state)))
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has_key = bool(state.key)
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result = False
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|
|
if mapper.inherits and not mapper.concrete:
|
|
statement = mapper._optimized_get_statement(state, attribute_names)
|
|
if statement is not None:
|
|
result = load_on_ident(
|
|
session.query(mapper).from_statement(statement),
|
|
None,
|
|
only_load_props=attribute_names,
|
|
refresh_state=state
|
|
)
|
|
|
|
if result is False:
|
|
if has_key:
|
|
identity_key = state.key
|
|
else:
|
|
# this codepath is rare - only valid when inside a flush, and the
|
|
# object is becoming persistent but hasn't yet been assigned
|
|
# an identity_key.
|
|
# check here to ensure we have the attrs we need.
|
|
pk_attrs = [mapper._columntoproperty[col].key
|
|
for col in mapper.primary_key]
|
|
if state.expired_attributes.intersection(pk_attrs):
|
|
raise sa_exc.InvalidRequestError(
|
|
"Instance %s cannot be refreshed - it's not "
|
|
" persistent and does not "
|
|
"contain a full primary key." % state_str(state))
|
|
identity_key = mapper._identity_key_from_state(state)
|
|
|
|
if (_none_set.issubset(identity_key) and \
|
|
not mapper.allow_partial_pks) or \
|
|
_none_set.issuperset(identity_key):
|
|
util.warn("Instance %s to be refreshed doesn't "
|
|
"contain a full primary key - can't be refreshed "
|
|
"(and shouldn't be expired, either)."
|
|
% state_str(state))
|
|
return
|
|
|
|
result = load_on_ident(
|
|
session.query(mapper),
|
|
identity_key,
|
|
refresh_state=state,
|
|
only_load_props=attribute_names)
|
|
|
|
# if instance is pending, a refresh operation
|
|
# may not complete (even if PK attributes are assigned)
|
|
if has_key and result is None:
|
|
raise orm_exc.ObjectDeletedError(state)
|