# mapper/util.py # Copyright (C) 2005, 2006, 2007, 2008, 2009 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 as sql_util, operators from sqlalchemy.orm.interfaces import MapperExtension, EXT_CONTINUE, PropComparator, MapperProperty, AttributeExtension from sqlalchemy.orm import attributes, exc 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 relation().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("'%s'" % 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): 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) 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 'alias'ed form of a mapped class for usage with Query. The ORM equivalent of a :class:`~sqlalchemy.sql.expression.Alias` object, this object mimics the mapped class using a __getattr__ scheme and maintains a reference to a real Alias object. It indicates to Query that the selectable produced for this class should be aliased, and also adapts PropComparators produced by the class' InstrumentedAttributes so that they adapt the "local" side of SQL expressions against the alias. """ def __init__(self, cls, alias=None, name=None): self.__mapper = _class_to_mapper(cls) self.__target = self.__mapper.class_ alias = alias or 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 '' % ( 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 not adapt_from: 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: 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 relation(), or a class-bound descriptor representing a relation. 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 relation(), or a class-bound descriptor representing a relation. """ 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 elif _is_mapped_class(entity): if isinstance(entity, type): mapper = class_mapper(entity, compile) else: if compile: mapper = entity.compile() else: mapper = entity return mapper, mapper._with_polymorphic_selectable, False else: return None, entity, 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): desc = getattr(entity, key) return desc, desc.property elif isinstance(entity, type): desc = attributes.manager_of_class(entity)[key] return desc, desc.property else: desc = entity.class_manager[key] return desc, desc.property 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): from sqlalchemy.orm import mapperlib as mapper if isinstance(cls, (AliasedClass, mapper.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