- merge ticket_1418 branch, [ticket:1418]

- The system of loader options has been entirely rearchitected to build
upon a much more comprehensive base, the :class:`.Load` object.  This
base allows any common loader option like :func:`.joinedload`,
:func:`.defer`, etc. to be used in a "chained" style for the purpose
of specifying options down a path, such as ``joinedload("foo").subqueryload("bar")``.
The new system supersedes the usage of dot-separated path names,
multiple attributes within options, and the usage of ``_all()`` options.
-  Added a new load option :func:`.orm.load_only`.  This allows a series
of column names to be specified as loading "only" those attributes,
deferring the rest.

1 files changed, 45 insertions, 276 deletions

diff --git a/lib/sqlalchemy/orm/interfaces.py b/lib/sqlalchemy/orm/interfaces.py
index 2f4aa5208..18723e4f6 100644
--- a/lib/sqlalchemy/orm/interfaces.py
+++ b/lib/sqlalchemy/orm/interfaces.py
@@ -21,7 +21,6 @@ from __future__ import absolute_import
 from .. import exc as sa_exc, util, inspect
 from ..sql import operators
 from collections import deque
-from .base import _is_aliased_class, _class_to_mapper
 from .base import ONETOMANY, MANYTOONE, MANYTOMANY, EXT_CONTINUE, EXT_STOP, NOT_EXTENSION
 from .base import _InspectionAttr, _MappedAttribute
 from .path_registry import PathRegistry
@@ -424,51 +423,57 @@ class StrategizedProperty(MapperProperty):
 
     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_loader(self, context, path):
+        load = None
 
-    def _get_context_strategy(self, context, path):
-        strategy_cls = path._inlined_get_for(self, context, 'loaderstrategy')
+        # use EntityRegistry.__getitem__()->PropRegistry here so
+        # that the path is stated in terms of our base
+        search_path = dict.__getitem__(path, self)
 
-        if not strategy_cls:
-            wc_key = self._wildcard_path
-            if wc_key and wc_key in context.attributes:
-                strategy_cls = context.attributes[wc_key]
+        # search among: exact match, "attr.*", "default" strategy
+        # if any.
+        for path_key in (
+                        search_path._loader_key,
+                        search_path._wildcard_path_loader_key,
+                        search_path._default_path_loader_key
+                    ):
+            if path_key in context.attributes:
+                load = context.attributes[path_key]
+                break
 
-        if strategy_cls:
-            try:
-                return self._strategies[strategy_cls]
-            except KeyError:
-                return self.__init_strategy(strategy_cls)
-        return self.strategy
+        return load
 
-    def _get_strategy(self, cls):
+    def _get_strategy(self, key):
         try:
-            return self._strategies[cls]
+            return self._strategies[key]
         except KeyError:
-            return self.__init_strategy(cls)
+            cls = self._strategy_lookup(*key)
+            self._strategies[key] = self._strategies[cls] = strategy = cls(self)
+            return strategy
 
-    def __init_strategy(self, cls):
-        self._strategies[cls] = strategy = cls(self)
-        return strategy
+    def _get_strategy_by_cls(self, cls):
+        return self._get_strategy(cls._strategy_keys[0])
 
     def setup(self, context, entity, path, adapter, **kwargs):
-        self._get_context_strategy(context, path).\
-                    setup_query(context, entity, path,
-                                    adapter, **kwargs)
+        loader = self._get_context_loader(context, path)
+        if loader and loader.strategy:
+            strat = self._get_strategy(loader.strategy)
+        else:
+            strat = self.strategy
+        strat.setup_query(context, entity, path, loader, adapter, **kwargs)
 
     def create_row_processor(self, context, path, mapper, row, adapter):
-        return self._get_context_strategy(context, path).\
-                    create_row_processor(context, path,
+        loader = self._get_context_loader(context, path)
+        if loader and loader.strategy:
+            strat = self._get_strategy(loader.strategy)
+        else:
+            strat = self.strategy
+        return strat.create_row_processor(context, path, loader,
                                     mapper, row, adapter)
 
     def do_init(self):
         self._strategies = {}
-        self.strategy = self.__init_strategy(self.strategy_class)
+        self.strategy = self._get_strategy_by_cls(self.strategy_class)
 
     def post_instrument_class(self, mapper):
         if self.is_primary() and \
@@ -479,17 +484,17 @@ class StrategizedProperty(MapperProperty):
     _strategies = collections.defaultdict(dict)
 
     @classmethod
-    def _strategy_for(cls, *keys):
+    def strategy_for(cls, **kw):
         def decorate(dec_cls):
-            for key in keys:
-                key = tuple(sorted(key.items()))
-                cls._strategies[cls][key] = dec_cls
+            dec_cls._strategy_keys = []
+            key = tuple(sorted(kw.items()))
+            cls._strategies[cls][key] = dec_cls
+            dec_cls._strategy_keys.append(key)
             return dec_cls
         return decorate
 
     @classmethod
-    def _strategy_lookup(cls, **kw):
-        key = tuple(sorted(kw.items()))
+    def _strategy_lookup(cls, *key):
         for prop_cls in cls.__mro__:
             if prop_cls in cls._strategies:
                 strategies = cls._strategies[prop_cls]
@@ -497,7 +502,7 @@ class StrategizedProperty(MapperProperty):
                     return strategies[key]
                 except KeyError:
                     pass
-        raise Exception("can't locate strategy for %s %s" % (cls, kw))
+        raise Exception("can't locate strategy for %s %s" % (cls, key))
 
 
 class MapperOption(object):
@@ -521,242 +526,6 @@ class MapperOption(object):
         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 _is_aliased_class(mapper):
-            searchfor = mapper
-        else:
-            searchfor = _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
-
-    @util.dependencies("sqlalchemy.orm.util")
-    def _process_paths(self, orm_util, query, raiseerr):
-        """reconcile the 'key' for this PropertyOption with
-        the current path and entities of the query.
-
-        Return a list of affected paths.
-
-        """
-        path = 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, str):
-                # 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._attributes, "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._attributes,
-                    "loaderstrategy",
-                    strategy
-                )
-        else:
-            paths[-1].set(
-                query._attributes,
-                "loaderstrategy",
-                strategy
-            )
-
-    def get_strategy_class(self):
-        raise NotImplementedError()
 
 
 class LoaderStrategy(object):
@@ -791,10 +560,10 @@ class LoaderStrategy(object):
     def init_class_attribute(self, mapper):
         pass
 
-    def setup_query(self, context, entity, path, adapter, **kwargs):
+    def setup_query(self, context, entity, path, loadopt, adapter, **kwargs):
         pass
 
-    def create_row_processor(self, context, path, mapper,
+    def create_row_processor(self, context, path, loadopt, mapper,
                                 row, adapter):
         """Return row processing functions which fulfill the contract
         specified by MapperProperty.create_row_processor.