# mapper/util.py
# Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
import sqlalchemy.exceptions as sa_exc
from sqlalchemy import sql,util
from sqlalchemy.sql import expression,util
from sqlalchemy.orm.interfaces import MapperExtension,EXT_CONTINUE,PropComparator,\
MapperProperty, AttributeExtension
from sqlalchemy.orm import attributes,exc
mapperlib = None
all_cascades = frozenset(("delete", "delete-orphan", "all", "merge",
"expunge", "save-update", "refresh-expire",
"none"))
_INSTRUMENTOR = ('mapper', 'instrumentor')
class CascadeOptions(object):
"""Keeps track of the options sent to relationship().cascade"""
def __init__(self, arg=""):
if not arg:
values = set()
else:
values = set(c.strip() for c in arg.split(','))
self.delete_orphan = "delete-orphan" in values
self.delete = "delete" in values or "all" in values
self.save_update = "save-update" in values or "all" in values
self.merge = "merge" in values or "all" in values
self.expunge = "expunge" in values or "all" in values
self.refresh_expire = "refresh-expire" in values or "all" in values
if self.delete_orphan and not self.delete:
util.warn("The 'delete-orphan' cascade option requires "
"'delete'. This will raise an error in 0.6.")
for x in values:
if x not in all_cascades:
raise sa_exc.ArgumentError("Invalid cascade option '%s'" % x)
def __contains__(self, item):
return getattr(self, item.replace("-", "_"), False)
def __repr__(self):
return "CascadeOptions(%s)" % repr(",".join(
[x for x in ['delete', 'save_update', 'merge', 'expunge',
'delete_orphan', 'refresh-expire']
if getattr(self, x, False) is True]))
class Validator(AttributeExtension):
"""Runs a validation method on an attribute value to be set or appended.
The Validator class is used by the :func:`~sqlalchemy.orm.validates`
decorator, and direct access is usually not needed.
"""
def __init__(self, key, validator):
"""Construct a new Validator.
key - name of the attribute to be validated;
will be passed as the second argument to
the validation method (the first is the object instance itself).
validator - an function or instance method which accepts
three arguments; an instance (usually just 'self' for a method),
the key name of the attribute, and the value. The function should
return the same value given, unless it wishes to modify it.
"""
self.key = key
self.validator = validator
def append(self, state, value, initiator):
return self.validator(state.obj(), self.key, value)
def set(self, state, value, oldvalue, initiator):
return self.validator(state.obj(), self.key, value)
def polymorphic_union(table_map, typecolname, aliasname='p_union'):
"""Create a ``UNION`` statement used by a polymorphic mapper.
See :ref:`concrete_inheritance` for an example of how
this is used.
"""
colnames = set()
colnamemaps = {}
types = {}
for key in table_map.keys():
table = table_map[key]
# mysql doesnt like selecting from a select; make it an alias of the select
if isinstance(table, sql.Select):
table = table.alias()
table_map[key] = table
m = {}
for c in table.c:
colnames.add(c.key)
m[c.key] = c
types[c.key] = c.type
colnamemaps[table] = m
def col(name, table):
try:
return colnamemaps[table][name]
except KeyError:
return sql.cast(sql.null(), types[name]).label(name)
result = []
for type, table in table_map.iteritems():
if typecolname is not None:
result.append(sql.select([col(name, table) for name in colnames] +
[sql.literal_column(
sql_util._quote_ddl_expr(type)).label(typecolname)
],
from_obj=[table]))
else:
result.append(sql.select([col(name, table) for name in colnames],
from_obj=[table]))
return sql.union_all(*result).alias(aliasname)
def identity_key(*args, **kwargs):
"""Get an identity key.
Valid call signatures:
* ``identity_key(class, ident)``
class
mapped class (must be a positional argument)
ident
primary key, if the key is composite this is a tuple
* ``identity_key(instance=instance)``
instance
object instance (must be given as a keyword arg)
* ``identity_key(class, row=row)``
class
mapped class (must be a positional argument)
row
result proxy row (must be given as a keyword arg)
"""
if args:
if len(args) == 1:
class_ = args[0]
try:
row = kwargs.pop("row")
except KeyError:
ident = kwargs.pop("ident")
elif len(args) == 2:
class_, ident = args
elif len(args) == 3:
class_, ident = args
else:
raise sa_exc.ArgumentError("expected up to three "
"positional arguments, got %s" % len(args))
if kwargs:
raise sa_exc.ArgumentError("unknown keyword arguments: %s"
% ", ".join(kwargs.keys()))
mapper = class_mapper(class_)
if "ident" in locals():
return mapper.identity_key_from_primary_key(ident)
return mapper.identity_key_from_row(row)
instance = kwargs.pop("instance")
if kwargs:
raise sa_exc.ArgumentError("unknown keyword arguments: %s"
% ", ".join(kwargs.keys()))
mapper = object_mapper(instance)
return mapper.identity_key_from_instance(instance)
class ExtensionCarrier(dict):
"""Fronts an ordered collection of MapperExtension objects.
Bundles multiple MapperExtensions into a unified callable unit,
encapsulating ordering, looping and EXT_CONTINUE logic. The
ExtensionCarrier implements the MapperExtension interface, e.g.::
carrier.after_insert(...args...)
The dictionary interface provides containment for implemented
method names mapped to a callable which executes that method
for participating extensions.
"""
interface = set(method for method in dir(MapperExtension)
if not method.startswith('_'))
def __init__(self, extensions=None):
self._extensions = []
for ext in extensions or ():
self.append(ext)
def copy(self):
return ExtensionCarrier(self._extensions)
def push(self, extension):
"""Insert a MapperExtension at the beginning of the collection."""
self._register(extension)
self._extensions.insert(0, extension)
def append(self, extension):
"""Append a MapperExtension at the end of the collection."""
self._register(extension)
self._extensions.append(extension)
def __iter__(self):
"""Iterate over MapperExtensions in the collection."""
return iter(self._extensions)
def _register(self, extension):
"""Register callable fronts for overridden interface methods."""
for method in self.interface.difference(self):
impl = getattr(extension, method, None)
if impl and impl is not getattr(MapperExtension, method):
self[method] = self._create_do(method)
def _create_do(self, method):
"""Return a closure that loops over impls of the named method."""
def _do(*args, **kwargs):
for ext in self._extensions:
ret = getattr(ext, method)(*args, **kwargs)
if ret is not EXT_CONTINUE:
return ret
else:
return EXT_CONTINUE
_do.__name__ = method
return _do
@staticmethod
def _pass(*args, **kwargs):
return EXT_CONTINUE
def __getattr__(self, key):
"""Delegate MapperExtension methods to bundled fronts."""
if key not in self.interface:
raise AttributeError(key)
return self.get(key, self._pass)
class ORMAdapter(sql_util.ColumnAdapter):
"""Extends ColumnAdapter to accept ORM entities.
The selectable is extracted from the given entity,
and the AliasedClass if any is referenced.
"""
def __init__(self, entity, equivalents=None, chain_to=None, adapt_required=False):
self.mapper, selectable, is_aliased_class = _entity_info(entity)
if is_aliased_class:
self.aliased_class = entity
else:
self.aliased_class = None
sql_util.ColumnAdapter.__init__(self, selectable, equivalents, chain_to, adapt_required=adapt_required)
def replace(self, elem):
entity = elem._annotations.get('parentmapper', None)
if not entity or entity.isa(self.mapper):
return sql_util.ColumnAdapter.replace(self, elem)
else:
return None
class AliasedClass(object):
"""Represents an "aliased" form of a mapped class for usage with Query.
The ORM equivalent of a :func:`sqlalchemy.sql.expression.alias`
construct, this object mimics the mapped class using a
__getattr__ scheme and maintains a reference to a
real :class:`~sqlalchemy.sql.expression.Alias` object.
Usage is via the :class:`~sqlalchemy.orm.aliased()` synonym::
# find all pairs of users with the same name
user_alias = aliased(User)
session.query(User, user_alias).\\
join((user_alias, User.id > user_alias.id)).\\
filter(User.name==user_alias.name)
"""
def __init__(self, cls, alias=None, name=None):
self.__mapper = _class_to_mapper(cls)
self.__target = self.__mapper.class_
if alias is None:
alias = self.__mapper._with_polymorphic_selectable.alias()
self.__adapter = sql_util.ClauseAdapter(alias, equivalents=self.__mapper._equivalent_columns)
self.__alias = alias
# used to assign a name to the RowTuple object
# returned by Query.
self._sa_label_name = name
self.__name__ = 'AliasedClass_' + str(self.__target)
def __getstate__(self):
return {'mapper':self.__mapper, 'alias':self.__alias, 'name':self._sa_label_name}
def __setstate__(self, state):
self.__mapper = state['mapper']
self.__target = self.__mapper.class_
alias = state['alias']
self.__adapter = sql_util.ClauseAdapter(alias, equivalents=self.__mapper._equivalent_columns)
self.__alias = alias
name = state['name']
self._sa_label_name = name
self.__name__ = 'AliasedClass_' + str(self.__target)
def __adapt_element(self, elem):
return self.__adapter.traverse(elem)._annotate({'parententity': self, 'parentmapper':self.__mapper})
def __adapt_prop(self, prop):
existing = getattr(self.__target, prop.key)
comparator = existing.comparator.adapted(self.__adapt_element)
queryattr = attributes.QueryableAttribute(prop.key,
impl=existing.impl, parententity=self, comparator=comparator)
setattr(self, prop.key, queryattr)
return queryattr
def __getattr__(self, key):
prop = self.__mapper._get_property(key, raiseerr=False)
if prop:
return self.__adapt_prop(prop)
for base in self.__target.__mro__:
try:
attr = object.__getattribute__(base, key)
except AttributeError:
continue
else:
break
else:
raise AttributeError(key)
if hasattr(attr, 'func_code'):
is_method = getattr(self.__target, key, None)
if is_method and is_method.im_self is not None:
return util.types.MethodType(attr.im_func, self, self)
else:
return None
elif hasattr(attr, '__get__'):
return attr.__get__(None, self)
else:
return attr
def __repr__(self):
return '<AliasedClass at 0x%x; %s>' % (
id(self), self.__target.__name__)
def _orm_annotate(element, exclude=None):
"""Deep copy the given ClauseElement, annotating each element with the "_orm_adapt" flag.
Elements within the exclude collection will be cloned but not annotated.
"""
return sql_util._deep_annotate(element, {'_orm_adapt':True}, exclude)
_orm_deannotate = sql_util._deep_deannotate
class _ORMJoin(expression.Join):
"""Extend Join to support ORM constructs as input."""
__visit_name__ = expression.Join.__visit_name__
def __init__(self, left, right, onclause=None, isouter=False, join_to_left=True):
adapt_from = None
if hasattr(left, '_orm_mappers'):
left_mapper = left._orm_mappers[1]
if join_to_left:
adapt_from = left.right
else:
left_mapper, left, left_is_aliased = _entity_info(left)
if join_to_left and (left_is_aliased or not left_mapper):
adapt_from = left
right_mapper, right, right_is_aliased = _entity_info(right)
if right_is_aliased:
adapt_to = right
else:
adapt_to = None
if left_mapper or right_mapper:
self._orm_mappers = (left_mapper, right_mapper)
if isinstance(onclause, basestring):
prop = left_mapper.get_property(onclause)
elif isinstance(onclause, attributes.QueryableAttribute):
if adapt_from is None:
adapt_from = onclause.__clause_element__()
prop = onclause.property
elif isinstance(onclause, MapperProperty):
prop = onclause
else:
prop = None
if prop:
pj, sj, source, dest, secondary, target_adapter = prop._create_joins(
source_selectable=adapt_from,
dest_selectable=adapt_to,
source_polymorphic=True,
dest_polymorphic=True,
of_type=right_mapper)
if sj is not None:
left = sql.join(left, secondary, pj, isouter)
onclause = sj
else:
onclause = pj
self._target_adapter = target_adapter
expression.Join.__init__(self, left, right, onclause, isouter)
def join(self, right, onclause=None, isouter=False, join_to_left=True):
return _ORMJoin(self, right, onclause, isouter, join_to_left)
def outerjoin(self, right, onclause=None, join_to_left=True):
return _ORMJoin(self, right, onclause, True, join_to_left)
def join(left, right, onclause=None, isouter=False, join_to_left=True):
"""Produce an inner join between left and right clauses.
In addition to the interface provided by
:func:`~sqlalchemy.sql.expression.join()`, left and right may be mapped
classes or AliasedClass instances. The onclause may be a
string name of a relationship(), or a class-bound descriptor
representing a relationship.
join_to_left indicates to attempt aliasing the ON clause,
in whatever form it is passed, to the selectable
passed as the left side. If False, the onclause
is used as is.
"""
return _ORMJoin(left, right, onclause, isouter, join_to_left)
def outerjoin(left, right, onclause=None, join_to_left=True):
"""Produce a left outer join between left and right clauses.
In addition to the interface provided by
:func:`~sqlalchemy.sql.expression.outerjoin()`, left and right may be mapped
classes or AliasedClass instances. The onclause may be a
string name of a relationship(), or a class-bound descriptor
representing a relationship.
"""
return _ORMJoin(left, right, onclause, True, join_to_left)
def with_parent(instance, prop):
"""Return criterion which selects instances with a given parent.
instance
a parent instance, which should be persistent or detached.
property
a class-attached descriptor, MapperProperty or string property name
attached to the parent instance.
\**kwargs
all extra keyword arguments are propagated to the constructor of
Query.
"""
if isinstance(prop, basestring):
mapper = object_mapper(instance)
prop = mapper.get_property(prop, resolve_synonyms=True)
elif isinstance(prop, attributes.QueryableAttribute):
prop = prop.property
return prop.compare(operators.eq, instance, value_is_parent=True)
def _entity_info(entity, compile=True):
"""Return mapping information given a class, mapper, or AliasedClass.
Returns 3-tuple of: mapper, mapped selectable, boolean indicating if this
is an aliased() construct.
If the given entity is not a mapper, mapped class, or aliased construct,
returns None, the entity, False. This is typically used to allow
unmapped selectables through.
"""
if isinstance(entity, AliasedClass):
return entity._AliasedClass__mapper, entity._AliasedClass__alias, True
global mapperlib
if mapperlib is None:
from sqlalchemy.orm import mapperlib
if isinstance(entity, mapperlib.Mapper):
mapper = entity
elif isinstance(entity, type):
class_manager = attributes.manager_of_class(entity)
if class_manager is None:
return None, entity, False
mapper = class_manager.mapper
else:
return None, entity, False
if compile:
mapper = mapper.compile()
return mapper, mapper._with_polymorphic_selectable, False
def _entity_descriptor(entity, key):
"""Return attribute/property information given an entity and string name.
Returns a 2-tuple representing InstrumentedAttribute/MapperProperty.
"""
if isinstance(entity, AliasedClass):
try:
desc = getattr(entity, key)
return desc, desc.property
except AttributeError:
raise sa_exc.InvalidRequestError("Entity '%s' has no property '%s'" % (entity, key))
elif isinstance(entity, type):
try:
desc = attributes.manager_of_class(entity)[key]
return desc, desc.property
except KeyError:
raise sa_exc.InvalidRequestError("Entity '%s' has no property '%s'" % (entity, key))
else:
try:
desc = entity.class_manager[key]
return desc, desc.property
except KeyError:
raise sa_exc.InvalidRequestError("Entity '%s' has no property '%s'" % (entity, key))
def _orm_columns(entity):
mapper, selectable, is_aliased_class = _entity_info(entity)
if isinstance(selectable, expression.Selectable):
return [c for c in selectable.c]
else:
return [selectable]
def _orm_selectable(entity):
mapper, selectable, is_aliased_class = _entity_info(entity)
return selectable
def _is_aliased_class(entity):
return isinstance(entity, AliasedClass)
def _state_mapper(state):
return state.manager.mapper
def object_mapper(instance):
"""Given an object, return the primary Mapper associated with the object instance.
Raises UnmappedInstanceError if no mapping is configured.
"""
try:
state = attributes.instance_state(instance)
if not state.manager.mapper:
raise exc.UnmappedInstanceError(instance)
return state.manager.mapper
except exc.NO_STATE:
raise exc.UnmappedInstanceError(instance)
def class_mapper(class_, compile=True):
"""Given a class, return the primary Mapper associated with the key.
Raises UnmappedClassError if no mapping is configured.
"""
try:
class_manager = attributes.manager_of_class(class_)
mapper = class_manager.mapper
# HACK until [ticket:1142] is complete
if mapper is None:
raise AttributeError
except exc.NO_STATE:
raise exc.UnmappedClassError(class_)
if compile:
mapper = mapper.compile()
return mapper
def _class_to_mapper(class_or_mapper, compile=True):
if _is_aliased_class(class_or_mapper):
return class_or_mapper._AliasedClass__mapper
elif isinstance(class_or_mapper, type):
return class_mapper(class_or_mapper, compile=compile)
elif hasattr(class_or_mapper, 'compile'):
if compile:
return class_or_mapper.compile()
else:
return class_or_mapper
else:
raise exc.UnmappedClassError(class_or_mapper)
def has_identity(object):
state = attributes.instance_state(object)
return _state_has_identity(state)
def _state_has_identity(state):
return bool(state.key)
def _is_mapped_class(cls):
global mapperlib
if mapperlib is None:
from sqlalchemy.orm import mapperlib
if isinstance(cls, (AliasedClass, mapperlib.Mapper)):
return True
if isinstance(cls, expression.ClauseElement):
return False
if isinstance(cls, type):
manager = attributes.manager_of_class(cls)
return manager and _INSTRUMENTOR in manager.info
return False
def instance_str(instance):
"""Return a string describing an instance."""
return state_str(attributes.instance_state(instance))
def state_str(state):
"""Return a string describing an instance via its InstanceState."""
if state is None:
return "None"
else:
return '<%s at 0x%x>' % (state.class_.__name__, id(state.obj()))
def attribute_str(instance, attribute):
return instance_str(instance) + "." + attribute
def state_attribute_str(state, attribute):
return state_str(state) + "." + attribute
def identity_equal(a, b):
if a is b:
return True
if a is None or b is None:
return False
try:
state_a = attributes.instance_state(a)
state_b = attributes.instance_state(b)
except exc.NO_STATE:
return False
if state_a.key is None or state_b.key is None:
return False
return state_a.key == state_b.key
# TODO: Avoid circular import.
attributes.identity_equal = identity_equal
attributes._is_aliased_class = _is_aliased_class
attributes._entity_info = _entity_info
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