pep484 ORM / SQL result support

after some experimentation it seems mypy is more amenable
to the generic types being fully integrated rather than
having separate spin-off types.   so key structures
like Result, Row, Select become generic.  For DML
Insert, Update, Delete, these are spun into type-specific
subclasses ReturningInsert, ReturningUpdate, ReturningDelete,
which is fine since the "row-ness" of these constructs
doesn't happen until returning() is called in any case.

a Tuple based model is then integrated so that these
objects can carry along information about their return
types.  Overloads at the .execute() level carry through
the Tuple from the invoked object to the result.

To suit the issue of AliasedClass generating attributes
that are dynamic, experimented with a custom subclass
AsAliased, but then just settled on having aliased()
lie to the type checker and return `Type[_O]`, essentially.
will need some type-related accessors for with_polymorphic()
also.

Additionally, identified an issue in Update when used
"mysql style" against a join(), it basically doesn't work
if asked to UPDATE two tables on the same column name.
added an error message to the specific condition where
it happens with a very non-specific error message that we
hit a thing we can't do right now, suggest multi-table
update as a possible cause.

Change-Id: I5eff7eefe1d6166ee74160b2785c5e6a81fa8b95

1 files changed, 198 insertions, 21 deletions

diff --git a/lib/sqlalchemy/orm/scoping.py b/lib/sqlalchemy/orm/scoping.py
index 93d18b8d7..9220c44c7 100644
--- a/lib/sqlalchemy/orm/scoping.py
+++ b/lib/sqlalchemy/orm/scoping.py
@@ -13,6 +13,7 @@ from typing import Dict
 from typing import Iterable
 from typing import Iterator
 from typing import Optional
+from typing import overload
 from typing import Sequence
 from typing import Tuple
 from typing import Type
@@ -20,8 +21,6 @@ from typing import TYPE_CHECKING
 from typing import TypeVar
 from typing import Union
 
-from . import exc as orm_exc
-from .base import class_mapper
 from .session import Session
 from .. import exc as sa_exc
 from .. import util
@@ -33,11 +32,13 @@ from ..util import warn_deprecated
 from ..util.typing import Protocol
 
 if TYPE_CHECKING:
+    from ._typing import _EntityType
     from ._typing import _IdentityKeyType
     from .identity import IdentityMap
     from .interfaces import ORMOption
     from .mapper import Mapper
     from .query import Query
+    from .query import RowReturningQuery
     from .session import _BindArguments
     from .session import _EntityBindKey
     from .session import _PKIdentityArgument
@@ -48,19 +49,33 @@ if TYPE_CHECKING:
     from ..engine import Engine
     from ..engine import Result
     from ..engine import Row
+    from ..engine import RowMapping
     from ..engine.interfaces import _CoreAnyExecuteParams
     from ..engine.interfaces import _CoreSingleExecuteParams
     from ..engine.interfaces import _ExecuteOptions
     from ..engine.interfaces import _ExecuteOptionsParameter
     from ..engine.result import ScalarResult
     from ..sql._typing import _ColumnsClauseArgument
+    from ..sql._typing import _T0
+    from ..sql._typing import _T1
+    from ..sql._typing import _T2
+    from ..sql._typing import _T3
+    from ..sql._typing import _T4
+    from ..sql._typing import _T5
+    from ..sql._typing import _T6
+    from ..sql._typing import _T7
+    from ..sql._typing import _TypedColumnClauseArgument as _TCCA
     from ..sql.base import Executable
     from ..sql.elements import ClauseElement
+    from ..sql.roles import TypedColumnsClauseRole
     from ..sql.selectable import ForUpdateArg
+    from ..sql.selectable import TypedReturnsRows
+
+_T = TypeVar("_T", bound=Any)
 
 
 class _QueryDescriptorType(Protocol):
-    def __get__(self, instance: Any, owner: Type[Any]) -> Optional[Query[Any]]:
+    def __get__(self, instance: Any, owner: Type[_T]) -> Query[_T]:
         ...
 
 
@@ -236,7 +251,7 @@ class scoped_session:
         self.registry.clear()
 
     def query_property(
-        self, query_cls: Optional[Type[Query[Any]]] = None
+        self, query_cls: Optional[Type[Query[_T]]] = None
     ) -> _QueryDescriptorType:
         """return a class property which produces a :class:`_query.Query`
         object
@@ -264,20 +279,13 @@ class scoped_session:
         """
 
         class query:
-            def __get__(
-                s, instance: Any, owner: Type[Any]
-            ) -> Optional[Query[Any]]:
-                try:
-                    mapper = class_mapper(owner)
-                    assert mapper is not None
-                    if query_cls:
-                        # custom query class
-                        return query_cls(mapper, session=self.registry())
-                    else:
-                        # session's configured query class
-                        return self.registry().query(mapper)
-                except orm_exc.UnmappedClassError:
-                    return None
+            def __get__(s, instance: Any, owner: Type[_O]) -> Query[_O]:
+                if query_cls:
+                    # custom query class
+                    return query_cls(owner, session=self.registry())  # type: ignore  # noqa: E501
+                else:
+                    # session's configured query class
+                    return self.registry().query(owner)
 
         return query()
 
@@ -548,6 +556,32 @@ class scoped_session:
 
         return self._proxied.delete(instance)
 
+    @overload
+    def execute(
+        self,
+        statement: TypedReturnsRows[_T],
+        params: Optional[_CoreAnyExecuteParams] = None,
+        *,
+        execution_options: _ExecuteOptionsParameter = util.EMPTY_DICT,
+        bind_arguments: Optional[_BindArguments] = None,
+        _parent_execute_state: Optional[Any] = None,
+        _add_event: Optional[Any] = None,
+    ) -> Result[_T]:
+        ...
+
+    @overload
+    def execute(
+        self,
+        statement: Executable,
+        params: Optional[_CoreAnyExecuteParams] = None,
+        *,
+        execution_options: _ExecuteOptionsParameter = util.EMPTY_DICT,
+        bind_arguments: Optional[_BindArguments] = None,
+        _parent_execute_state: Optional[Any] = None,
+        _add_event: Optional[Any] = None,
+    ) -> Result[Any]:
+        ...
+
     def execute(
         self,
         statement: Executable,
@@ -557,7 +591,7 @@ class scoped_session:
         bind_arguments: Optional[_BindArguments] = None,
         _parent_execute_state: Optional[Any] = None,
         _add_event: Optional[Any] = None,
-    ) -> Result:
+    ) -> Result[Any]:
         r"""Execute a SQL expression construct.
 
         .. container:: class_bases
@@ -1430,8 +1464,103 @@ class scoped_session:
 
         return self._proxied.merge(instance, load=load, options=options)
 
+    @overload
+    def query(self, _entity: _EntityType[_O]) -> Query[_O]:
+        ...
+
+    @overload
     def query(
-        self, *entities: _ColumnsClauseArgument, **kwargs: Any
+        self, _colexpr: TypedColumnsClauseRole[_T]
+    ) -> RowReturningQuery[Tuple[_T]]:
+        ...
+
+    # START OVERLOADED FUNCTIONS self.query RowReturningQuery 2-8
+
+    # code within this block is **programmatically,
+    # statically generated** by tools/generate_tuple_map_overloads.py
+
+    @overload
+    def query(
+        self, __ent0: _TCCA[_T0], __ent1: _TCCA[_T1]
+    ) -> RowReturningQuery[Tuple[_T0, _T1]]:
+        ...
+
+    @overload
+    def query(
+        self, __ent0: _TCCA[_T0], __ent1: _TCCA[_T1], __ent2: _TCCA[_T2]
+    ) -> RowReturningQuery[Tuple[_T0, _T1, _T2]]:
+        ...
+
+    @overload
+    def query(
+        self,
+        __ent0: _TCCA[_T0],
+        __ent1: _TCCA[_T1],
+        __ent2: _TCCA[_T2],
+        __ent3: _TCCA[_T3],
+    ) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3]]:
+        ...
+
+    @overload
+    def query(
+        self,
+        __ent0: _TCCA[_T0],
+        __ent1: _TCCA[_T1],
+        __ent2: _TCCA[_T2],
+        __ent3: _TCCA[_T3],
+        __ent4: _TCCA[_T4],
+    ) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4]]:
+        ...
+
+    @overload
+    def query(
+        self,
+        __ent0: _TCCA[_T0],
+        __ent1: _TCCA[_T1],
+        __ent2: _TCCA[_T2],
+        __ent3: _TCCA[_T3],
+        __ent4: _TCCA[_T4],
+        __ent5: _TCCA[_T5],
+    ) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4, _T5]]:
+        ...
+
+    @overload
+    def query(
+        self,
+        __ent0: _TCCA[_T0],
+        __ent1: _TCCA[_T1],
+        __ent2: _TCCA[_T2],
+        __ent3: _TCCA[_T3],
+        __ent4: _TCCA[_T4],
+        __ent5: _TCCA[_T5],
+        __ent6: _TCCA[_T6],
+    ) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4, _T5, _T6]]:
+        ...
+
+    @overload
+    def query(
+        self,
+        __ent0: _TCCA[_T0],
+        __ent1: _TCCA[_T1],
+        __ent2: _TCCA[_T2],
+        __ent3: _TCCA[_T3],
+        __ent4: _TCCA[_T4],
+        __ent5: _TCCA[_T5],
+        __ent6: _TCCA[_T6],
+        __ent7: _TCCA[_T7],
+    ) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4, _T5, _T6, _T7]]:
+        ...
+
+    # END OVERLOADED FUNCTIONS self.query
+
+    @overload
+    def query(
+        self, *entities: _ColumnsClauseArgument[Any], **kwargs: Any
+    ) -> Query[Any]:
+        ...
+
+    def query(
+        self, *entities: _ColumnsClauseArgument[Any], **kwargs: Any
     ) -> Query[Any]:
         r"""Return a new :class:`_query.Query` object corresponding to this
         :class:`_orm.Session`.
@@ -1559,6 +1688,30 @@ class scoped_session:
 
         return self._proxied.rollback()
 
+    @overload
+    def scalar(
+        self,
+        statement: TypedReturnsRows[Tuple[_T]],
+        params: Optional[_CoreSingleExecuteParams] = None,
+        *,
+        execution_options: _ExecuteOptionsParameter = util.EMPTY_DICT,
+        bind_arguments: Optional[_BindArguments] = None,
+        **kw: Any,
+    ) -> Optional[_T]:
+        ...
+
+    @overload
+    def scalar(
+        self,
+        statement: Executable,
+        params: Optional[_CoreSingleExecuteParams] = None,
+        *,
+        execution_options: _ExecuteOptionsParameter = util.EMPTY_DICT,
+        bind_arguments: Optional[_BindArguments] = None,
+        **kw: Any,
+    ) -> Any:
+        ...
+
     def scalar(
         self,
         statement: Executable,
@@ -1590,6 +1743,30 @@ class scoped_session:
             **kw,
         )
 
+    @overload
+    def scalars(
+        self,
+        statement: TypedReturnsRows[Tuple[_T]],
+        params: Optional[_CoreSingleExecuteParams] = None,
+        *,
+        execution_options: _ExecuteOptionsParameter = util.EMPTY_DICT,
+        bind_arguments: Optional[_BindArguments] = None,
+        **kw: Any,
+    ) -> ScalarResult[_T]:
+        ...
+
+    @overload
+    def scalars(
+        self,
+        statement: Executable,
+        params: Optional[_CoreSingleExecuteParams] = None,
+        *,
+        execution_options: _ExecuteOptionsParameter = util.EMPTY_DICT,
+        bind_arguments: Optional[_BindArguments] = None,
+        **kw: Any,
+    ) -> ScalarResult[Any]:
+        ...
+
     def scalars(
         self,
         statement: Executable,
@@ -1848,7 +2025,7 @@ class scoped_session:
         ident: Union[Any, Tuple[Any, ...]] = None,
         *,
         instance: Optional[Any] = None,
-        row: Optional[Row] = None,
+        row: Optional[Union[Row[Any], RowMapping]] = None,
         identity_token: Optional[Any] = None,
     ) -> _IdentityKeyType[Any]:
         r"""Return an identity key.