mirror of
https://github.com/janeczku/calibre-web
synced 2024-11-28 20:39:59 +00:00
859 lines
28 KiB
Python
859 lines
28 KiB
Python
# orm/interfaces.py
|
|
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
|
|
|
"""
|
|
|
|
Contains various base classes used throughout the ORM.
|
|
|
|
Defines the now deprecated ORM extension classes as well
|
|
as ORM internals.
|
|
|
|
Other than the deprecated extensions, this module and the
|
|
classes within should be considered mostly private.
|
|
|
|
"""
|
|
from __future__ import absolute_import
|
|
|
|
from .. import exc as sa_exc, util, inspect
|
|
from ..sql import operators
|
|
from collections import deque
|
|
|
|
orm_util = util.importlater('sqlalchemy.orm', 'util')
|
|
collections = util.importlater('sqlalchemy.orm', 'collections')
|
|
|
|
__all__ = (
|
|
'AttributeExtension',
|
|
'EXT_CONTINUE',
|
|
'EXT_STOP',
|
|
'ExtensionOption',
|
|
'InstrumentationManager',
|
|
'LoaderStrategy',
|
|
'MapperExtension',
|
|
'MapperOption',
|
|
'MapperProperty',
|
|
'PropComparator',
|
|
'PropertyOption',
|
|
'SessionExtension',
|
|
'StrategizedOption',
|
|
'StrategizedProperty',
|
|
)
|
|
|
|
EXT_CONTINUE = util.symbol('EXT_CONTINUE')
|
|
EXT_STOP = util.symbol('EXT_STOP')
|
|
|
|
ONETOMANY = util.symbol('ONETOMANY')
|
|
MANYTOONE = util.symbol('MANYTOONE')
|
|
MANYTOMANY = util.symbol('MANYTOMANY')
|
|
|
|
from .deprecated_interfaces import AttributeExtension, \
|
|
SessionExtension, \
|
|
MapperExtension
|
|
|
|
|
|
NOT_EXTENSION = util.symbol('NOT_EXTENSION')
|
|
"""Symbol indicating an :class:`_InspectionAttr` that's
|
|
not part of sqlalchemy.ext.
|
|
|
|
Is assigned to the :attr:`._InspectionAttr.extension_type`
|
|
attibute.
|
|
|
|
"""
|
|
|
|
class _InspectionAttr(object):
|
|
"""A base class applied to all ORM objects that can be returned
|
|
by the :func:`.inspect` function.
|
|
|
|
The attributes defined here allow the usage of simple boolean
|
|
checks to test basic facts about the object returned.
|
|
|
|
While the boolean checks here are basically the same as using
|
|
the Python isinstance() function, the flags here can be used without
|
|
the need to import all of these classes, and also such that
|
|
the SQLAlchemy class system can change while leaving the flags
|
|
here intact for forwards-compatibility.
|
|
|
|
"""
|
|
|
|
is_selectable = False
|
|
"""Return True if this object is an instance of :class:`.Selectable`."""
|
|
|
|
is_aliased_class = False
|
|
"""True if this object is an instance of :class:`.AliasedClass`."""
|
|
|
|
is_instance = False
|
|
"""True if this object is an instance of :class:`.InstanceState`."""
|
|
|
|
is_mapper = False
|
|
"""True if this object is an instance of :class:`.Mapper`."""
|
|
|
|
is_property = False
|
|
"""True if this object is an instance of :class:`.MapperProperty`."""
|
|
|
|
is_attribute = False
|
|
"""True if this object is a Python :term:`descriptor`.
|
|
|
|
This can refer to one of many types. Usually a
|
|
:class:`.QueryableAttribute` which handles attributes events on behalf
|
|
of a :class:`.MapperProperty`. But can also be an extension type
|
|
such as :class:`.AssociationProxy` or :class:`.hybrid_property`.
|
|
The :attr:`._InspectionAttr.extension_type` will refer to a constant
|
|
identifying the specific subtype.
|
|
|
|
.. seealso::
|
|
|
|
:attr:`.Mapper.all_orm_descriptors`
|
|
|
|
"""
|
|
|
|
is_clause_element = False
|
|
"""True if this object is an instance of :class:`.ClauseElement`."""
|
|
|
|
extension_type = NOT_EXTENSION
|
|
"""The extension type, if any.
|
|
Defaults to :data:`.interfaces.NOT_EXTENSION`
|
|
|
|
.. versionadded:: 0.8.0
|
|
|
|
.. seealso::
|
|
|
|
:data:`.HYBRID_METHOD`
|
|
|
|
:data:`.HYBRID_PROPERTY`
|
|
|
|
:data:`.ASSOCIATION_PROXY`
|
|
|
|
"""
|
|
|
|
class _MappedAttribute(object):
|
|
"""Mixin for attributes which should be replaced by mapper-assigned
|
|
attributes.
|
|
|
|
"""
|
|
|
|
|
|
class MapperProperty(_MappedAttribute, _InspectionAttr):
|
|
"""Manage the relationship of a ``Mapper`` to a single class
|
|
attribute, as well as that attribute as it appears on individual
|
|
instances of the class, including attribute instrumentation,
|
|
attribute access, loading behavior, and dependency calculations.
|
|
|
|
The most common occurrences of :class:`.MapperProperty` are the
|
|
mapped :class:`.Column`, which is represented in a mapping as
|
|
an instance of :class:`.ColumnProperty`,
|
|
and a reference to another class produced by :func:`.relationship`,
|
|
represented in the mapping as an instance of
|
|
:class:`.RelationshipProperty`.
|
|
|
|
"""
|
|
|
|
cascade = frozenset()
|
|
"""The set of 'cascade' attribute names.
|
|
|
|
This collection is checked before the 'cascade_iterator' method is called.
|
|
|
|
"""
|
|
|
|
is_property = True
|
|
|
|
def setup(self, context, entity, path, adapter, **kwargs):
|
|
"""Called by Query for the purposes of constructing a SQL statement.
|
|
|
|
Each MapperProperty associated with the target mapper processes the
|
|
statement referenced by the query context, adding columns and/or
|
|
criterion as appropriate.
|
|
"""
|
|
|
|
pass
|
|
|
|
def create_row_processor(self, context, path,
|
|
mapper, row, adapter):
|
|
"""Return a 3-tuple consisting of three row processing functions.
|
|
|
|
"""
|
|
return None, None, None
|
|
|
|
def cascade_iterator(self, type_, state, visited_instances=None,
|
|
halt_on=None):
|
|
"""Iterate through instances related to the given instance for
|
|
a particular 'cascade', starting with this MapperProperty.
|
|
|
|
Return an iterator3-tuples (instance, mapper, state).
|
|
|
|
Note that the 'cascade' collection on this MapperProperty is
|
|
checked first for the given type before cascade_iterator is called.
|
|
|
|
See PropertyLoader for the related instance implementation.
|
|
"""
|
|
|
|
return iter(())
|
|
|
|
def set_parent(self, parent, init):
|
|
self.parent = parent
|
|
|
|
def instrument_class(self, mapper): # pragma: no-coverage
|
|
raise NotImplementedError()
|
|
|
|
@util.memoized_property
|
|
def info(self):
|
|
"""Info dictionary associated with the object, allowing user-defined
|
|
data to be associated with this :class:`.MapperProperty`.
|
|
|
|
The dictionary is generated when first accessed. Alternatively,
|
|
it can be specified as a constructor argument to the
|
|
:func:`.column_property`, :func:`.relationship`, or :func:`.composite`
|
|
functions.
|
|
|
|
.. versionadded:: 0.8 Added support for .info to all
|
|
:class:`.MapperProperty` subclasses.
|
|
|
|
.. seealso::
|
|
|
|
:attr:`.QueryableAttribute.info`
|
|
|
|
:attr:`.SchemaItem.info`
|
|
|
|
"""
|
|
return {}
|
|
|
|
_configure_started = False
|
|
_configure_finished = False
|
|
|
|
def init(self):
|
|
"""Called after all mappers are created to assemble
|
|
relationships between mappers and perform other post-mapper-creation
|
|
initialization steps.
|
|
|
|
"""
|
|
self._configure_started = True
|
|
self.do_init()
|
|
self._configure_finished = True
|
|
|
|
@property
|
|
def class_attribute(self):
|
|
"""Return the class-bound descriptor corresponding to this
|
|
:class:`.MapperProperty`.
|
|
|
|
This is basically a ``getattr()`` call::
|
|
|
|
return getattr(self.parent.class_, self.key)
|
|
|
|
I.e. if this :class:`.MapperProperty` were named ``addresses``,
|
|
and the class to which it is mapped is ``User``, this sequence
|
|
is possible::
|
|
|
|
>>> from sqlalchemy import inspect
|
|
>>> mapper = inspect(User)
|
|
>>> addresses_property = mapper.attrs.addresses
|
|
>>> addresses_property.class_attribute is User.addresses
|
|
True
|
|
>>> User.addresses.property is addresses_property
|
|
True
|
|
|
|
|
|
"""
|
|
|
|
return getattr(self.parent.class_, self.key)
|
|
|
|
def do_init(self):
|
|
"""Perform subclass-specific initialization post-mapper-creation
|
|
steps.
|
|
|
|
This is a template method called by the ``MapperProperty``
|
|
object's init() method.
|
|
|
|
"""
|
|
|
|
pass
|
|
|
|
def post_instrument_class(self, mapper):
|
|
"""Perform instrumentation adjustments that need to occur
|
|
after init() has completed.
|
|
|
|
"""
|
|
pass
|
|
|
|
def is_primary(self):
|
|
"""Return True if this ``MapperProperty``'s mapper is the
|
|
primary mapper for its class.
|
|
|
|
This flag is used to indicate that the ``MapperProperty`` can
|
|
define attribute instrumentation for the class at the class
|
|
level (as opposed to the individual instance level).
|
|
"""
|
|
|
|
return not self.parent.non_primary
|
|
|
|
def merge(self, session, source_state, source_dict, dest_state,
|
|
dest_dict, load, _recursive):
|
|
"""Merge the attribute represented by this ``MapperProperty``
|
|
from source to destination object"""
|
|
|
|
pass
|
|
|
|
def compare(self, operator, value, **kw):
|
|
"""Return a compare operation for the columns represented by
|
|
this ``MapperProperty`` to the given value, which may be a
|
|
column value or an instance. 'operator' is an operator from
|
|
the operators module, or from sql.Comparator.
|
|
|
|
By default uses the PropComparator attached to this MapperProperty
|
|
under the attribute name "comparator".
|
|
"""
|
|
|
|
return operator(self.comparator, value)
|
|
|
|
def __repr__(self):
|
|
return '<%s at 0x%x; %s>' % (
|
|
self.__class__.__name__,
|
|
id(self), getattr(self, 'key', 'no key'))
|
|
|
|
class PropComparator(operators.ColumnOperators):
|
|
"""Defines boolean, comparison, and other operators for
|
|
:class:`.MapperProperty` objects.
|
|
|
|
SQLAlchemy allows for operators to
|
|
be redefined at both the Core and ORM level. :class:`.PropComparator`
|
|
is the base class of operator redefinition for ORM-level operations,
|
|
including those of :class:`.ColumnProperty`,
|
|
:class:`.RelationshipProperty`, and :class:`.CompositeProperty`.
|
|
|
|
.. note:: With the advent of Hybrid properties introduced in SQLAlchemy
|
|
0.7, as well as Core-level operator redefinition in
|
|
SQLAlchemy 0.8, the use case for user-defined :class:`.PropComparator`
|
|
instances is extremely rare. See :ref:`hybrids_toplevel` as well
|
|
as :ref:`types_operators`.
|
|
|
|
User-defined subclasses of :class:`.PropComparator` may be created. The
|
|
built-in Python comparison and math operator methods, such as
|
|
:meth:`.operators.ColumnOperators.__eq__`,
|
|
:meth:`.operators.ColumnOperators.__lt__`, and
|
|
:meth:`.operators.ColumnOperators.__add__`, can be overridden to provide
|
|
new operator behavior. The custom :class:`.PropComparator` is passed to
|
|
the :class:`.MapperProperty` instance via the ``comparator_factory``
|
|
argument. In each case,
|
|
the appropriate subclass of :class:`.PropComparator` should be used::
|
|
|
|
# definition of custom PropComparator subclasses
|
|
|
|
from sqlalchemy.orm.properties import \\
|
|
ColumnProperty,\\
|
|
CompositeProperty,\\
|
|
RelationshipProperty
|
|
|
|
class MyColumnComparator(ColumnProperty.Comparator):
|
|
def __eq__(self, other):
|
|
return self.__clause_element__() == other
|
|
|
|
class MyRelationshipComparator(RelationshipProperty.Comparator):
|
|
def any(self, expression):
|
|
"define the 'any' operation"
|
|
# ...
|
|
|
|
class MyCompositeComparator(CompositeProperty.Comparator):
|
|
def __gt__(self, other):
|
|
"redefine the 'greater than' operation"
|
|
|
|
return sql.and_(*[a>b for a, b in
|
|
zip(self.__clause_element__().clauses,
|
|
other.__composite_values__())])
|
|
|
|
|
|
# application of custom PropComparator subclasses
|
|
|
|
from sqlalchemy.orm import column_property, relationship, composite
|
|
from sqlalchemy import Column, String
|
|
|
|
class SomeMappedClass(Base):
|
|
some_column = column_property(Column("some_column", String),
|
|
comparator_factory=MyColumnComparator)
|
|
|
|
some_relationship = relationship(SomeOtherClass,
|
|
comparator_factory=MyRelationshipComparator)
|
|
|
|
some_composite = composite(
|
|
Column("a", String), Column("b", String),
|
|
comparator_factory=MyCompositeComparator
|
|
)
|
|
|
|
Note that for column-level operator redefinition, it's usually
|
|
simpler to define the operators at the Core level, using the
|
|
:attr:`.TypeEngine.comparator_factory` attribute. See
|
|
:ref:`types_operators` for more detail.
|
|
|
|
See also:
|
|
|
|
:class:`.ColumnProperty.Comparator`
|
|
|
|
:class:`.RelationshipProperty.Comparator`
|
|
|
|
:class:`.CompositeProperty.Comparator`
|
|
|
|
:class:`.ColumnOperators`
|
|
|
|
:ref:`types_operators`
|
|
|
|
:attr:`.TypeEngine.comparator_factory`
|
|
|
|
"""
|
|
|
|
def __init__(self, prop, parentmapper, adapter=None):
|
|
self.prop = self.property = prop
|
|
self._parentmapper = parentmapper
|
|
self.adapter = adapter
|
|
|
|
def __clause_element__(self):
|
|
raise NotImplementedError("%r" % self)
|
|
|
|
def adapted(self, adapter):
|
|
"""Return a copy of this PropComparator which will use the given
|
|
adaption function on the local side of generated expressions.
|
|
|
|
"""
|
|
|
|
return self.__class__(self.prop, self._parentmapper, adapter)
|
|
|
|
@util.memoized_property
|
|
def info(self):
|
|
return self.property.info
|
|
|
|
@staticmethod
|
|
def any_op(a, b, **kwargs):
|
|
return a.any(b, **kwargs)
|
|
|
|
@staticmethod
|
|
def has_op(a, b, **kwargs):
|
|
return a.has(b, **kwargs)
|
|
|
|
@staticmethod
|
|
def of_type_op(a, class_):
|
|
return a.of_type(class_)
|
|
|
|
def of_type(self, class_):
|
|
"""Redefine this object in terms of a polymorphic subclass.
|
|
|
|
Returns a new PropComparator from which further criterion can be
|
|
evaluated.
|
|
|
|
e.g.::
|
|
|
|
query.join(Company.employees.of_type(Engineer)).\\
|
|
filter(Engineer.name=='foo')
|
|
|
|
:param \class_: a class or mapper indicating that criterion will be
|
|
against this specific subclass.
|
|
|
|
|
|
"""
|
|
|
|
return self.operate(PropComparator.of_type_op, class_)
|
|
|
|
def any(self, criterion=None, **kwargs):
|
|
"""Return true if this collection contains any member that meets the
|
|
given criterion.
|
|
|
|
The usual implementation of ``any()`` is
|
|
:meth:`.RelationshipProperty.Comparator.any`.
|
|
|
|
:param criterion: an optional ClauseElement formulated against the
|
|
member class' table or attributes.
|
|
|
|
:param \**kwargs: key/value pairs corresponding to member class
|
|
attribute names which will be compared via equality to the
|
|
corresponding values.
|
|
|
|
"""
|
|
|
|
return self.operate(PropComparator.any_op, criterion, **kwargs)
|
|
|
|
def has(self, criterion=None, **kwargs):
|
|
"""Return true if this element references a member which meets the
|
|
given criterion.
|
|
|
|
The usual implementation of ``has()`` is
|
|
:meth:`.RelationshipProperty.Comparator.has`.
|
|
|
|
:param criterion: an optional ClauseElement formulated against the
|
|
member class' table or attributes.
|
|
|
|
:param \**kwargs: key/value pairs corresponding to member class
|
|
attribute names which will be compared via equality to the
|
|
corresponding values.
|
|
|
|
"""
|
|
|
|
return self.operate(PropComparator.has_op, criterion, **kwargs)
|
|
|
|
|
|
class StrategizedProperty(MapperProperty):
|
|
"""A MapperProperty which uses selectable strategies to affect
|
|
loading behavior.
|
|
|
|
There is a single strategy selected by default. Alternate
|
|
strategies can be selected at Query time through the usage of
|
|
``StrategizedOption`` objects via the Query.options() method.
|
|
|
|
"""
|
|
|
|
strategy_wildcard_key = None
|
|
|
|
@util.memoized_property
|
|
def _wildcard_path(self):
|
|
if self.strategy_wildcard_key:
|
|
return ('loaderstrategy', (self.strategy_wildcard_key,))
|
|
else:
|
|
return None
|
|
|
|
def _get_context_strategy(self, context, path):
|
|
strategy_cls = path._inlined_get_for(self, context, 'loaderstrategy')
|
|
|
|
if not strategy_cls:
|
|
wc_key = self._wildcard_path
|
|
if wc_key and wc_key in context.attributes:
|
|
strategy_cls = context.attributes[wc_key]
|
|
|
|
if strategy_cls:
|
|
try:
|
|
return self._strategies[strategy_cls]
|
|
except KeyError:
|
|
return self.__init_strategy(strategy_cls)
|
|
return self.strategy
|
|
|
|
def _get_strategy(self, cls):
|
|
try:
|
|
return self._strategies[cls]
|
|
except KeyError:
|
|
return self.__init_strategy(cls)
|
|
|
|
def __init_strategy(self, cls):
|
|
self._strategies[cls] = strategy = cls(self)
|
|
return strategy
|
|
|
|
def setup(self, context, entity, path, adapter, **kwargs):
|
|
self._get_context_strategy(context, path).\
|
|
setup_query(context, entity, path,
|
|
adapter, **kwargs)
|
|
|
|
def create_row_processor(self, context, path, mapper, row, adapter):
|
|
return self._get_context_strategy(context, path).\
|
|
create_row_processor(context, path,
|
|
mapper, row, adapter)
|
|
|
|
def do_init(self):
|
|
self._strategies = {}
|
|
self.strategy = self.__init_strategy(self.strategy_class)
|
|
|
|
def post_instrument_class(self, mapper):
|
|
if self.is_primary() and \
|
|
not mapper.class_manager._attr_has_impl(self.key):
|
|
self.strategy.init_class_attribute(mapper)
|
|
|
|
|
|
class MapperOption(object):
|
|
"""Describe a modification to a Query."""
|
|
|
|
propagate_to_loaders = False
|
|
"""if True, indicate this option should be carried along
|
|
Query object generated by scalar or object lazy loaders.
|
|
"""
|
|
|
|
def process_query(self, query):
|
|
pass
|
|
|
|
def process_query_conditionally(self, query):
|
|
"""same as process_query(), except that this option may not
|
|
apply to the given query.
|
|
|
|
Used when secondary loaders resend existing options to a new
|
|
Query."""
|
|
|
|
self.process_query(query)
|
|
|
|
|
|
class PropertyOption(MapperOption):
|
|
"""A MapperOption that is applied to a property off the mapper or
|
|
one of its child mappers, identified by a dot-separated key
|
|
or list of class-bound attributes. """
|
|
|
|
def __init__(self, key, mapper=None):
|
|
self.key = key
|
|
self.mapper = mapper
|
|
|
|
def process_query(self, query):
|
|
self._process(query, True)
|
|
|
|
def process_query_conditionally(self, query):
|
|
self._process(query, False)
|
|
|
|
def _process(self, query, raiseerr):
|
|
paths = self._process_paths(query, raiseerr)
|
|
if paths:
|
|
self.process_query_property(query, paths)
|
|
|
|
def process_query_property(self, query, paths):
|
|
pass
|
|
|
|
def __getstate__(self):
|
|
d = self.__dict__.copy()
|
|
d['key'] = ret = []
|
|
for token in util.to_list(self.key):
|
|
if isinstance(token, PropComparator):
|
|
ret.append((token._parentmapper.class_, token.key))
|
|
else:
|
|
ret.append(token)
|
|
return d
|
|
|
|
def __setstate__(self, state):
|
|
ret = []
|
|
for key in state['key']:
|
|
if isinstance(key, tuple):
|
|
cls, propkey = key
|
|
ret.append(getattr(cls, propkey))
|
|
else:
|
|
ret.append(key)
|
|
state['key'] = tuple(ret)
|
|
self.__dict__ = state
|
|
|
|
def _find_entity_prop_comparator(self, query, token, mapper, raiseerr):
|
|
if orm_util._is_aliased_class(mapper):
|
|
searchfor = mapper
|
|
else:
|
|
searchfor = orm_util._class_to_mapper(mapper)
|
|
for ent in query._mapper_entities:
|
|
if ent.corresponds_to(searchfor):
|
|
return ent
|
|
else:
|
|
if raiseerr:
|
|
if not list(query._mapper_entities):
|
|
raise sa_exc.ArgumentError(
|
|
"Query has only expression-based entities - "
|
|
"can't find property named '%s'."
|
|
% (token, )
|
|
)
|
|
else:
|
|
raise sa_exc.ArgumentError(
|
|
"Can't find property '%s' on any entity "
|
|
"specified in this Query. Note the full path "
|
|
"from root (%s) to target entity must be specified."
|
|
% (token, ",".join(str(x) for
|
|
x in query._mapper_entities))
|
|
)
|
|
else:
|
|
return None
|
|
|
|
def _find_entity_basestring(self, query, token, raiseerr):
|
|
for ent in query._mapper_entities:
|
|
# return only the first _MapperEntity when searching
|
|
# based on string prop name. Ideally object
|
|
# attributes are used to specify more exactly.
|
|
return ent
|
|
else:
|
|
if raiseerr:
|
|
raise sa_exc.ArgumentError(
|
|
"Query has only expression-based entities - "
|
|
"can't find property named '%s'."
|
|
% (token, )
|
|
)
|
|
else:
|
|
return None
|
|
|
|
def _process_paths(self, query, raiseerr):
|
|
"""reconcile the 'key' for this PropertyOption with
|
|
the current path and entities of the query.
|
|
|
|
Return a list of affected paths.
|
|
|
|
"""
|
|
path = orm_util.PathRegistry.root
|
|
entity = None
|
|
paths = []
|
|
no_result = []
|
|
|
|
# _current_path implies we're in a
|
|
# secondary load with an existing path
|
|
current_path = list(query._current_path.path)
|
|
|
|
tokens = deque(self.key)
|
|
while tokens:
|
|
token = tokens.popleft()
|
|
if isinstance(token, basestring):
|
|
# wildcard token
|
|
if token.endswith(':*'):
|
|
return [path.token(token)]
|
|
sub_tokens = token.split(".", 1)
|
|
token = sub_tokens[0]
|
|
tokens.extendleft(sub_tokens[1:])
|
|
|
|
# exhaust current_path before
|
|
# matching tokens to entities
|
|
if current_path:
|
|
if current_path[1].key == token:
|
|
current_path = current_path[2:]
|
|
continue
|
|
else:
|
|
return no_result
|
|
|
|
if not entity:
|
|
entity = self._find_entity_basestring(
|
|
query,
|
|
token,
|
|
raiseerr)
|
|
if entity is None:
|
|
return no_result
|
|
path_element = entity.entity_zero
|
|
mapper = entity.mapper
|
|
|
|
if hasattr(mapper.class_, token):
|
|
prop = getattr(mapper.class_, token).property
|
|
else:
|
|
if raiseerr:
|
|
raise sa_exc.ArgumentError(
|
|
"Can't find property named '%s' on the "
|
|
"mapped entity %s in this Query. " % (
|
|
token, mapper)
|
|
)
|
|
else:
|
|
return no_result
|
|
elif isinstance(token, PropComparator):
|
|
prop = token.property
|
|
|
|
# exhaust current_path before
|
|
# matching tokens to entities
|
|
if current_path:
|
|
if current_path[0:2] == \
|
|
[token._parententity, prop]:
|
|
current_path = current_path[2:]
|
|
continue
|
|
else:
|
|
return no_result
|
|
|
|
if not entity:
|
|
entity = self._find_entity_prop_comparator(
|
|
query,
|
|
prop.key,
|
|
token._parententity,
|
|
raiseerr)
|
|
if not entity:
|
|
return no_result
|
|
|
|
path_element = entity.entity_zero
|
|
mapper = entity.mapper
|
|
else:
|
|
raise sa_exc.ArgumentError(
|
|
"mapper option expects "
|
|
"string key or list of attributes")
|
|
assert prop is not None
|
|
if raiseerr and not prop.parent.common_parent(mapper):
|
|
raise sa_exc.ArgumentError("Attribute '%s' does not "
|
|
"link from element '%s'" % (token, path_element))
|
|
|
|
path = path[path_element][prop]
|
|
|
|
paths.append(path)
|
|
|
|
if getattr(token, '_of_type', None):
|
|
ac = token._of_type
|
|
ext_info = inspect(ac)
|
|
path_element = mapper = ext_info.mapper
|
|
if not ext_info.is_aliased_class:
|
|
ac = orm_util.with_polymorphic(
|
|
ext_info.mapper.base_mapper,
|
|
ext_info.mapper, aliased=True,
|
|
_use_mapper_path=True)
|
|
ext_info = inspect(ac)
|
|
path.set(query, "path_with_polymorphic", ext_info)
|
|
else:
|
|
path_element = mapper = getattr(prop, 'mapper', None)
|
|
if mapper is None and tokens:
|
|
raise sa_exc.ArgumentError(
|
|
"Attribute '%s' of entity '%s' does not "
|
|
"refer to a mapped entity" %
|
|
(token, entity)
|
|
)
|
|
|
|
if current_path:
|
|
# ran out of tokens before
|
|
# current_path was exhausted.
|
|
assert not tokens
|
|
return no_result
|
|
|
|
return paths
|
|
|
|
|
|
class StrategizedOption(PropertyOption):
|
|
"""A MapperOption that affects which LoaderStrategy will be used
|
|
for an operation by a StrategizedProperty.
|
|
"""
|
|
|
|
chained = False
|
|
|
|
def process_query_property(self, query, paths):
|
|
strategy = self.get_strategy_class()
|
|
if self.chained:
|
|
for path in paths:
|
|
path.set(
|
|
query,
|
|
"loaderstrategy",
|
|
strategy
|
|
)
|
|
else:
|
|
paths[-1].set(
|
|
query,
|
|
"loaderstrategy",
|
|
strategy
|
|
)
|
|
|
|
def get_strategy_class(self):
|
|
raise NotImplementedError()
|
|
|
|
|
|
class LoaderStrategy(object):
|
|
"""Describe the loading behavior of a StrategizedProperty object.
|
|
|
|
The ``LoaderStrategy`` interacts with the querying process in three
|
|
ways:
|
|
|
|
* it controls the configuration of the ``InstrumentedAttribute``
|
|
placed on a class to handle the behavior of the attribute. this
|
|
may involve setting up class-level callable functions to fire
|
|
off a select operation when the attribute is first accessed
|
|
(i.e. a lazy load)
|
|
|
|
* it processes the ``QueryContext`` at statement construction time,
|
|
where it can modify the SQL statement that is being produced.
|
|
Simple column attributes may add their represented column to the
|
|
list of selected columns, *eager loading* properties may add
|
|
``LEFT OUTER JOIN`` clauses to the statement.
|
|
|
|
* It produces "row processor" functions at result fetching time.
|
|
These "row processor" functions populate a particular attribute
|
|
on a particular mapped instance.
|
|
|
|
"""
|
|
def __init__(self, parent):
|
|
self.parent_property = parent
|
|
self.is_class_level = False
|
|
self.parent = self.parent_property.parent
|
|
self.key = self.parent_property.key
|
|
|
|
def init_class_attribute(self, mapper):
|
|
pass
|
|
|
|
def setup_query(self, context, entity, path, adapter, **kwargs):
|
|
pass
|
|
|
|
def create_row_processor(self, context, path, mapper,
|
|
row, adapter):
|
|
"""Return row processing functions which fulfill the contract
|
|
specified by MapperProperty.create_row_processor.
|
|
|
|
StrategizedProperty delegates its create_row_processor method
|
|
directly to this method. """
|
|
|
|
return None, None, None
|
|
|
|
def __str__(self):
|
|
return str(self.parent_property)
|