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-rw-r--r--lib/sqlalchemy/engine/base.py11
-rw-r--r--lib/sqlalchemy/mods/legacy_session.py1
-rw-r--r--lib/sqlalchemy/mods/threadlocal.py17
-rw-r--r--lib/sqlalchemy/orm/attributes.py (renamed from lib/sqlalchemy/attributes.py)7
-rw-r--r--lib/sqlalchemy/orm/mapper.py154
-rw-r--r--lib/sqlalchemy/orm/properties.py3
-rw-r--r--lib/sqlalchemy/orm/query.py9
-rw-r--r--lib/sqlalchemy/orm/strategies.py7
-rw-r--r--lib/sqlalchemy/orm/sync.py4
-rw-r--r--lib/sqlalchemy/orm/unitofwork.py3
10 files changed, 121 insertions, 95 deletions
diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index e348b19ee..e4ff22746 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -16,11 +16,14 @@ class ConnectionProvider(object):
raise NotImplementedError()
class Dialect(sql.AbstractDialect):
- """Adds behavior to the execution of queries to provide
- support for column defaults, differences between paramstyles, quirks between post-execution behavior,
- and a general consistentization of the behavior of various DBAPIs.
+ """Defines the behavior of a specific database/DBAPI.
+
+ Any aspect of metadata defintion, SQL query generation, execution, result-set handling,
+ or anything else which varies between databases is defined under the general category of
+ the Dialect. The Dialect acts as a factory for other database-specific object implementations
+ including ExecutionContext, Compiled, DefaultGenerator, and TypeEngine.
- The Dialect should also implement the following two attributes:
+ All Dialects implement the following attributes:
positional - True if the paramstyle for this Dialect is positional
diff --git a/lib/sqlalchemy/mods/legacy_session.py b/lib/sqlalchemy/mods/legacy_session.py
index 7dbeda924..a28cd3dac 100644
--- a/lib/sqlalchemy/mods/legacy_session.py
+++ b/lib/sqlalchemy/mods/legacy_session.py
@@ -1,3 +1,4 @@
+"""a plugin that emulates 0.1 Session behavior."""
import sqlalchemy.orm.objectstore as objectstore
import sqlalchemy.orm.unitofwork as unitofwork
diff --git a/lib/sqlalchemy/mods/threadlocal.py b/lib/sqlalchemy/mods/threadlocal.py
index 87d7f271c..6fce85954 100644
--- a/lib/sqlalchemy/mods/threadlocal.py
+++ b/lib/sqlalchemy/mods/threadlocal.py
@@ -1,11 +1,3 @@
-from sqlalchemy import util, engine, mapper
-from sqlalchemy.ext.sessioncontext import SessionContext
-import sqlalchemy.ext.assignmapper as assignmapper
-from sqlalchemy.orm.mapper import global_extensions
-from sqlalchemy.orm.session import Session
-import sqlalchemy
-import sys, types
-
"""this plugin installs thread-local behavior at the Engine and Session level.
The default Engine strategy will be "threadlocal", producing TLocalEngine instances for create_engine by default.
@@ -20,6 +12,15 @@ Note: this mod creates a global, thread-local session context named sqlalchemy.o
while this mod is installed will reference this global context when creating new mapped object instances.
"""
+from sqlalchemy import util, engine, mapper
+from sqlalchemy.ext.sessioncontext import SessionContext
+import sqlalchemy.ext.assignmapper as assignmapper
+from sqlalchemy.orm.mapper import global_extensions
+from sqlalchemy.orm.session import Session
+import sqlalchemy
+import sys, types
+
+
__all__ = ['Objectstore', 'assign_mapper']
class Objectstore(object):
diff --git a/lib/sqlalchemy/attributes.py b/lib/sqlalchemy/orm/attributes.py
index 67c23ba95..f5eb669f3 100644
--- a/lib/sqlalchemy/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -4,8 +4,10 @@
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
-import util
+from sqlalchemy import util
+import util as orm_util
import weakref
+from sqlalchemy import logging
class InstrumentedAttribute(object):
"""a property object that instruments attribute access on object instances. All methods correspond to
@@ -182,6 +184,7 @@ class InstrumentedAttribute(object):
if callable_ is not None:
if passive:
return InstrumentedAttribute.PASSIVE_NORESULT
+ self.logger.debug("Executing lazy callable on %s.%s" % (orm_util.instance_str(obj), self.key))
values = callable_()
l = InstrumentedList(self, obj, self._adapt_list(values), init=False)
@@ -203,6 +206,7 @@ class InstrumentedAttribute(object):
if callable_ is not None:
if passive:
return InstrumentedAttribute.PASSIVE_NORESULT
+ self.logger.debug("Executing lazy callable on %s.%s" % (orm_util.instance_str(obj), self.key))
value = callable_()
obj.__dict__[self.key] = value
@@ -302,6 +306,7 @@ class InstrumentedAttribute(object):
self.sethasparent(value, False)
for ext in self.extensions:
ext.delete(event or self, obj, value)
+InstrumentedAttribute.logger = logging.class_logger(InstrumentedAttribute)
class InstrumentedList(object):
"""instruments a list-based attribute. all mutator operations (i.e. append, remove, etc.) will fire off events to the
diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index b3dbe7a92..1327644b2 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -21,7 +21,7 @@ mapper_registry = weakref.WeakKeyDictionary()
# a list of MapperExtensions that will be installed in all mappers by default
global_extensions = []
-# a constant returned by _getattrbycolumn to indicate
+# a constant returned by get_attr_by_column to indicate
# this mapper is not handling an attribute for a particular
# column
NO_ATTRIBUTE = object()
@@ -289,10 +289,6 @@ class Mapper(object):
def _compile_extensions(self):
"""goes through the global_extensions list as well as the list of MapperExtensions
specified for this Mapper and creates a linked list of those extensions."""
- # uber-pendantic style of making mapper chain, as various testbase/
- # threadlocal/assignmapper combinations keep putting dupes etc. in the list
- # TODO: do something that isnt 21 lines....
-
extlist = util.Set()
for ext_class in global_extensions:
if isinstance(ext_class, MapperExtension):
@@ -307,7 +303,7 @@ class Mapper(object):
self.extension = _ExtensionCarrier()
for ext in extlist:
- self.extension.elements.append(ext)
+ self.extension.append(ext)
def _compile_inheritance(self):
"""determines if this Mapper inherits from another mapper, and if so calculates the mapped_table
@@ -744,7 +740,7 @@ class Mapper(object):
def primary_key_from_instance(self, instance):
"""return the list of primary key values for the given instance."""
- return [self._getattrbycolumn(instance, column) for column in self.pks_by_table[self.mapped_table]]
+ return [self.get_attr_by_column(instance, column) for column in self.pks_by_table[self.mapped_table]]
def instance_key(self, instance):
"""deprecated. a synonym for identity_key_from_instance."""
@@ -773,21 +769,27 @@ class Mapper(object):
raise exceptions.InvalidRequestError("No column %s.%s is configured on mapper %s..." % (column.table.name, column.name, str(self)))
return prop[0]
- def _getattrbycolumn(self, obj, column, raiseerror=True):
+ def get_attr_by_column(self, obj, column, raiseerror=True):
+ """return an instance attribute using a Column as the key."""
prop = self._getpropbycolumn(column, raiseerror)
if prop is None:
return NO_ATTRIBUTE
#self.__log_debug("get column attribute '%s' from instance %s" % (column.key, mapperutil.instance_str(obj)))
return prop.getattr(obj)
- def _setattrbycolumn(self, obj, column, value):
+ def set_attr_by_column(self, obj, column, value):
+ """set the value of an instance attribute using a Column as the key."""
self.columntoproperty[column][0].setattr(obj, value)
def save_obj(self, objects, uowtransaction, postupdate=False, post_update_cols=None, single=False):
- """save a list of objects.
+ """issue INSERT and/or UPDATE statements for a list of objects.
+
+ this is called within the context of a UOWTransaction during a flush operation.
- this method is called within a unit of work flush() process. It saves objects that are mapped not just
- by this mapper, but inherited mappers as well, so that insert ordering of polymorphic objects is maintained."""
+ save_obj issues SQL statements not just for instances mapped directly by this mapper, but
+ for instances mapped by all inheriting mappers as well. This is to maintain proper insert
+ ordering among a polymorphic chain of instances. Therefore save_obj is typically
+ called only on a "base mapper", or a mapper which does not inherit from any other mapper."""
self.__log_debug("save_obj() start, " + (single and "non-batched" or "batched"))
@@ -848,7 +850,7 @@ class Mapper(object):
for col in table.columns:
if col is mapper.version_id_col:
if not isinsert:
- params[col._label] = mapper._getattrbycolumn(obj, col)
+ params[col._label] = mapper.get_attr_by_column(obj, col)
params[col.key] = params[col._label] + 1
else:
params[col.key] = 1
@@ -857,14 +859,14 @@ class Mapper(object):
if not isinsert:
# doing an UPDATE? put primary key values as "WHERE" parameters
# matching the bindparam we are creating below, i.e. "<tablename>_<colname>"
- params[col._label] = mapper._getattrbycolumn(obj, col)
+ params[col._label] = mapper.get_attr_by_column(obj, col)
else:
# doing an INSERT, primary key col ?
# if the primary key values are not populated,
# leave them out of the INSERT altogether, since PostGres doesn't want
# them to be present for SERIAL to take effect. A SQLEngine that uses
# explicit sequences will put them back in if they are needed
- value = mapper._getattrbycolumn(obj, col)
+ value = mapper.get_attr_by_column(obj, col)
if value is not None:
params[col.key] = value
elif mapper.polymorphic_on is not None and mapper.polymorphic_on.shares_lineage(col):
@@ -882,7 +884,7 @@ class Mapper(object):
if post_update_cols is not None and col not in post_update_cols:
continue
elif is_row_switch:
- params[col.key] = self._getattrbycolumn(obj, col)
+ params[col.key] = self.get_attr_by_column(obj, col)
hasdata = True
continue
prop = mapper._getpropbycolumn(col, False)
@@ -901,7 +903,7 @@ class Mapper(object):
# default. if its None and theres no default, we still might
# not want to put it in the col list but SQLIte doesnt seem to like that
# if theres no columns at all
- value = mapper._getattrbycolumn(obj, col, False)
+ value = mapper.get_attr_by_column(obj, col, False)
if value is NO_ATTRIBUTE:
continue
if col.default is None or value is not None:
@@ -955,8 +957,8 @@ class Mapper(object):
if primary_key is not None:
i = 0
for col in mapper.pks_by_table[table]:
- if mapper._getattrbycolumn(obj, col) is None and len(primary_key) > i:
- mapper._setattrbycolumn(obj, col, primary_key[i])
+ if mapper.get_attr_by_column(obj, col) is None and len(primary_key) > i:
+ mapper.set_attr_by_column(obj, col, primary_key[i])
i+=1
mapper._postfetch(connection, table, obj, c, c.last_inserted_params())
@@ -987,26 +989,29 @@ class Mapper(object):
if resultproxy.lastrow_has_defaults():
clause = sql.and_()
for p in self.pks_by_table[table]:
- clause.clauses.append(p == self._getattrbycolumn(obj, p))
+ clause.clauses.append(p == self.get_attr_by_column(obj, p))
row = connection.execute(table.select(clause), None).fetchone()
for c in table.c:
- if self._getattrbycolumn(obj, c, False) is None:
- self._setattrbycolumn(obj, c, row[c])
+ if self.get_attr_by_column(obj, c, False) is None:
+ self.set_attr_by_column(obj, c, row[c])
else:
for c in table.c:
if c.primary_key or not params.has_key(c.name):
continue
- v = self._getattrbycolumn(obj, c, False)
+ v = self.get_attr_by_column(obj, c, False)
if v is NO_ATTRIBUTE:
continue
elif v != params.get_original(c.name):
- self._setattrbycolumn(obj, c, params.get_original(c.name))
+ self.set_attr_by_column(obj, c, params.get_original(c.name))
def delete_obj(self, objects, uowtransaction):
- """called by a UnitOfWork object to delete objects, which involves a
- DELETE statement for each table used by this mapper, for each object in the list."""
+ """issue DELETE statements for a list of objects.
+
+ this is called within the context of a UOWTransaction during a flush operation."""
+
+ self.__log_debug("delete_obj() start")
+
connection = uowtransaction.transaction.connection(self)
- #print "DELETE_OBJ MAPPER", self.class_.__name__, objects
[self.extension.before_delete(self, connection, obj) for obj in objects]
deleted_objects = util.Set()
@@ -1021,9 +1026,9 @@ class Mapper(object):
else:
delete.append(params)
for col in self.pks_by_table[table]:
- params[col.key] = self._getattrbycolumn(obj, col)
+ params[col.key] = self.get_attr_by_column(obj, col)
if self.version_id_col is not None:
- params[self.version_id_col.key] = self._getattrbycolumn(obj, self.version_id_col)
+ params[self.version_id_col.key] = self.get_attr_by_column(obj, self.version_id_col)
deleted_objects.add(obj)
if len(delete):
def comparator(a, b):
@@ -1123,8 +1128,8 @@ class Mapper(object):
instance = context.session._get(identitykey)
self.__log_debug("_instance(): using existing instance %s identity %s" % (mapperutil.instance_str(instance), str(identitykey)))
isnew = False
- if context.version_check and self.version_id_col is not None and self._getattrbycolumn(instance, self.version_id_col) != row[self.version_id_col]:
- raise exceptions.ConcurrentModificationError("Instance '%s' version of %s does not match %s" % (instance, self._getattrbycolumn(instance, self.version_id_col), row[self.version_id_col]))
+ if context.version_check and self.version_id_col is not None and self.get_attr_by_column(instance, self.version_id_col) != row[self.version_id_col]:
+ raise exceptions.ConcurrentModificationError("Instance '%s' version of %s does not match %s" % (instance, self.get_attr_by_column(instance, self.version_id_col), row[self.version_id_col]))
if populate_existing or context.session.is_expired(instance, unexpire=True):
if not context.identity_map.has_key(identitykey):
@@ -1186,8 +1191,11 @@ class Mapper(object):
return obj
def translate_row(self, tomapper, row):
- """attempts to take a row and translate its values to a row that can
- be understood by another mapper."""
+ """translate the column keys of a row into a new or proxied row that
+ can be understood by another mapper.
+
+ This can be used in conjunction with populate_instance to populate
+ an instance using an alternate mapper."""
newrow = util.DictDecorator(row)
for c in tomapper.mapped_table.c:
c2 = self.mapped_table.corresponding_column(c, keys_ok=True, raiseerr=True)
@@ -1195,9 +1203,11 @@ class Mapper(object):
newrow[c] = row[c2]
return newrow
- def populate_instance(self, selectcontext, instance, row, identitykey, isnew, frommapper=None):
- if frommapper is not None:
- row = frommapper.translate_row(self, row)
+ def populate_instance(self, selectcontext, instance, row, identitykey, isnew):
+ """populate an instance from a result row.
+
+ This method iterates through the list of MapperProperty objects attached to this Mapper
+ and calls each properties execute() method."""
for prop in self.__props.values():
prop.execute(selectcontext, instance, row, identitykey, isnew)
@@ -1213,6 +1223,24 @@ class MapperExtension(object):
Note: this is not called if a session is provided with the __init__ params (i.e. _sa_session)"""
return EXT_PASS
+ def load(self, query, *args, **kwargs):
+ """override the load method of the Query object.
+
+ the return value of this method is used as the result of query.load() if the
+ value is anything other than EXT_PASS."""
+ return EXT_PASS
+ def get(self, query, *args, **kwargs):
+ """override the get method of the Query object.
+
+ the return value of this method is used as the result of query.get() if the
+ value is anything other than EXT_PASS."""
+ return EXT_PASS
+ def get_by(self, query, *args, **kwargs):
+ """override the get_by method of the Query object.
+
+ the return value of this method is used as the result of query.get_by() if the
+ value is anything other than EXT_PASS."""
+ return EXT_PASS
def select_by(self, query, *args, **kwargs):
"""override the select_by method of the Query object.
@@ -1271,14 +1299,7 @@ class MapperExtension(object):
as relationships to other classes). If this method returns EXT_PASS, instance population
will proceed normally. If any other value or None is returned, instance population
will not proceed, giving this extension an opportunity to populate the instance itself,
- if desired..
-
- A common usage of this method is to have population performed by an alternate mapper. This can
- be acheived via the populate_instance() call on Mapper.
-
- def populate_instance(self, mapper, selectcontext, instance, row, identitykey, isnew):
- othermapper.populate_instance(selectcontext, instance, row, identitykey, isnew, frommapper=mapper)
- return None
+ if desired.
"""
return EXT_PASS
def before_insert(self, mapper, connection, instance):
@@ -1304,41 +1325,24 @@ class MapperExtension(object):
class _ExtensionCarrier(MapperExtension):
def __init__(self):
- self.elements = []
+ self.__elements = []
+ self.__callables = {}
def insert(self, extension):
"""insert a MapperExtension at the beginning of this ExtensionCarrier's list."""
- self.elements.insert(0, extension)
+ self.__elements.insert(0, extension)
def append(self, extension):
"""append a MapperExtension at the end of this ExtensionCarrier's list."""
- self.elements.append(extension)
- # TODO: shrink down this approach using __getattribute__ or similar
- def get_session(self):
- return self._do('get_session')
- def select_by(self, *args, **kwargs):
- return self._do('select_by', *args, **kwargs)
- def select(self, *args, **kwargs):
- return self._do('select', *args, **kwargs)
- def create_instance(self, *args, **kwargs):
- return self._do('create_instance', *args, **kwargs)
- def append_result(self, *args, **kwargs):
- return self._do('append_result', *args, **kwargs)
- def populate_instance(self, *args, **kwargs):
- return self._do('populate_instance', *args, **kwargs)
- def before_insert(self, *args, **kwargs):
- return self._do('before_insert', *args, **kwargs)
- def before_update(self, *args, **kwargs):
- return self._do('before_update', *args, **kwargs)
- def after_update(self, *args, **kwargs):
- return self._do('after_update', *args, **kwargs)
- def after_insert(self, *args, **kwargs):
- return self._do('after_insert', *args, **kwargs)
- def before_delete(self, *args, **kwargs):
- return self._do('before_delete', *args, **kwargs)
- def after_delete(self, *args, **kwargs):
- return self._do('after_delete', *args, **kwargs)
-
+ self.__elements.append(extension)
+ def __getattribute__(self, key):
+ if key in MapperExtension.__dict__:
+ try:
+ return self.__callables[key]
+ except KeyError:
+ return self.__callables.setdefault(key, lambda *args, **kwargs:self._do(key, *args, **kwargs))
+ else:
+ return super(_ExtensionCarrier, self).__getattribute__(key)
def _do(self, funcname, *args, **kwargs):
- for elem in self.elements:
+ for elem in self.__elements:
if elem is self:
raise exceptions.AssertionError("ExtensionCarrier set to itself")
ret = getattr(elem, funcname)(*args, **kwargs)
@@ -1346,7 +1350,7 @@ class _ExtensionCarrier(MapperExtension):
return ret
else:
return EXT_PASS
-
+
class ExtensionOption(MapperExtension):
def __init__(self, ext):
self.ext = ext
diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index 768b51959..501903983 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -9,10 +9,11 @@ well as relationships. the objects rely upon the LoaderStrategy objects in the
module to handle load operations. PropertyLoader also relies upon the dependency.py module
to handle flush-time dependency sorting and processing."""
-from sqlalchemy import sql, schema, util, attributes, exceptions, sql_util, logging
+from sqlalchemy import sql, schema, util, exceptions, sql_util, logging
import mapper
import sync
import strategies
+import attributes
import session as sessionlib
import dependency
import util as mapperutil
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index 82ed4e1a0..607b37fd9 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -54,6 +54,9 @@ class Query(object):
The ident argument is a scalar or tuple of primary key column values
in the order of the table def's primary key columns."""
+ ret = self.extension.get(self, ident, **kwargs)
+ if ret is not mapper.EXT_PASS:
+ return ret
key = self.mapper.identity_key(ident)
return self._get(key, ident, **kwargs)
@@ -63,6 +66,9 @@ class Query(object):
If not found, raises an exception. The method will *remove all pending changes* to the object
already existing in the Session. The ident argument is a scalar or tuple of primary
key column values in the order of the table def's primary key columns."""
+ ret = self.extension.load(self, ident, **kwargs)
+ if ret is not mapper.EXT_PASS:
+ return ret
key = self.mapper.identity_key(ident)
instance = self._get(key, ident, reload=True, **kwargs)
if instance is None:
@@ -83,6 +89,9 @@ class Query(object):
e.g. u = usermapper.get_by(user_name = 'fred')
"""
+ ret = self.extension.get_by(self, *args, **params)
+ if ret is not mapper.EXT_PASS:
+ return ret
x = self.select_whereclause(self.join_by(*args, **params), limit=1)
if x:
return x[0]
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index 916a60d25..ac6b37e33 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -4,6 +4,8 @@
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
+"""sqlalchemy.orm.interfaces.LoaderStrategy implementations, and related MapperOptions."""
+
from sqlalchemy import sql, schema, util, attributes, exceptions, sql_util, logging
import mapper, query
from interfaces import *
@@ -11,7 +13,6 @@ import session as sessionlib
import util as mapperutil
import sets, random
-"""sqlalchemy.orm.interfaces.LoaderStrategy implementations, and related MapperOptions."""
class ColumnLoader(LoaderStrategy):
def init(self):
@@ -73,7 +74,7 @@ class DeferredColumnLoader(LoaderStrategy):
clause = sql.and_()
for primary_key in pk:
- attr = self.parent._getattrbycolumn(instance, primary_key)
+ attr = self.parent.get_attr_by_column(instance, primary_key)
if not attr:
return None
clause.clauses.append(primary_key == attr)
@@ -178,7 +179,7 @@ class LazyLoader(AbstractRelationLoader):
return None
#print "setting up loader, lazywhere", str(self.lazywhere), "binds", self.lazybinds
for col, bind in self.lazybinds.iteritems():
- params[bind.key] = self.parent._getattrbycolumn(instance, col)
+ params[bind.key] = self.parent.get_attr_by_column(instance, col)
if params[bind.key] is None:
allparams = False
break
diff --git a/lib/sqlalchemy/orm/sync.py b/lib/sqlalchemy/orm/sync.py
index 5f0331e16..6fe848a6f 100644
--- a/lib/sqlalchemy/orm/sync.py
+++ b/lib/sqlalchemy/orm/sync.py
@@ -132,7 +132,7 @@ class SyncRule(object):
if clearkeys or source is None:
value = None
else:
- value = self.source_mapper._getattrbycolumn(source, self.source_column)
+ value = self.source_mapper.get_attr_by_column(source, self.source_column)
if isinstance(dest, dict):
dest[self.dest_column.key] = value
else:
@@ -141,7 +141,7 @@ class SyncRule(object):
if logging.is_debug_enabled(self.logger):
self.logger.debug("execute() instances: %s(%s)->%s(%s) ('%s')" % (mapperutil.instance_str(source), str(self.source_column), mapperutil.instance_str(dest), str(self.dest_column), value))
- self.dest_mapper._setattrbycolumn(dest, self.dest_column, value)
+ self.dest_mapper.set_attr_by_column(dest, self.dest_column, value)
SyncRule.logger = logging.class_logger(SyncRule)
diff --git a/lib/sqlalchemy/orm/unitofwork.py b/lib/sqlalchemy/orm/unitofwork.py
index c4fd92e36..815ffe029 100644
--- a/lib/sqlalchemy/orm/unitofwork.py
+++ b/lib/sqlalchemy/orm/unitofwork.py
@@ -14,8 +14,9 @@ an "identity map" pattern. The Unit of Work then maintains lists of objects tha
dirty, or deleted and provides the capability to flush all those changes at once.
"""
-from sqlalchemy import attributes, util, logging, topological
+from sqlalchemy import util, logging, topological
import sqlalchemy
+import attributes
from sqlalchemy.exceptions import *
import StringIO
import weakref
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