runtime annotation fixes for relationship

* derive uselist=False when fwd ref passed to relationship

  This case needs to work whether or not the class name
  is a forward ref.  we dont allow the colleciton to be a
  forward ref so this will work.

* fix issues with MappedCollection

  When using string annotations or __future__.annotations,
  we need to do more parsing in order to get the target
  collection properly

Change-Id: I9e5a1358b62d060a8815826f98190801a9cc0b68

5 files changed, 42 insertions, 10 deletions

diff --git a/lib/sqlalchemy/orm/__init__.py b/lib/sqlalchemy/orm/__init__.py
index 4f19ba946..539cf2600 100644
--- a/lib/sqlalchemy/orm/__init__.py
+++ b/lib/sqlalchemy/orm/__init__.py
@@ -87,6 +87,10 @@ from .interfaces import PropComparator as PropComparator
 from .interfaces import UserDefinedOption as UserDefinedOption
 from .loading import merge_frozen_result as merge_frozen_result
 from .loading import merge_result as merge_result
+from .mapped_collection import attribute_mapped_collection
+from .mapped_collection import column_mapped_collection
+from .mapped_collection import mapped_collection
+from .mapped_collection import MappedCollection
 from .mapper import configure_mappers as configure_mappers
 from .mapper import Mapper as Mapper
 from .mapper import reconstructor as reconstructor
diff --git a/lib/sqlalchemy/orm/clsregistry.py b/lib/sqlalchemy/orm/clsregistry.py
index b3fcd29ea..dd79eb1d0 100644
--- a/lib/sqlalchemy/orm/clsregistry.py
+++ b/lib/sqlalchemy/orm/clsregistry.py
@@ -463,6 +463,7 @@ class _class_resolver:
         generic_match = re.match(r"(.+)\[(.+)\]", name)
 
         if generic_match:
+            clsarg = generic_match.group(2).strip("'")
             raise exc.InvalidRequestError(
                 f"When initializing mapper {self.prop.parent}, "
                 f'expression "relationship({self.arg!r})" seems to be '
@@ -470,7 +471,7 @@ class _class_resolver:
                 "please state the generic argument "
                 "using an annotation, e.g. "
                 f'"{self.prop.key}: Mapped[{generic_match.group(1)}'
-                f'[{generic_match.group(2)}]] = relationship()"'
+                f"['{clsarg}']] = relationship()\""
             ) from err
         else:
             raise exc.InvalidRequestError(
diff --git a/lib/sqlalchemy/orm/relationships.py b/lib/sqlalchemy/orm/relationships.py
index 630f6898f..77a95a195 100644
--- a/lib/sqlalchemy/orm/relationships.py
+++ b/lib/sqlalchemy/orm/relationships.py
@@ -1724,11 +1724,12 @@ class Relationship(
                     self.collection_class = collection_class
             else:
                 self.uselist = False
+
             if argument.__args__:  # type: ignore
                 if issubclass(
                     argument.__origin__, typing.Mapping  # type: ignore
                 ):
-                    type_arg = argument.__args__[1]  # type: ignore
+                    type_arg = argument.__args__[-1]  # type: ignore
                 else:
                     type_arg = argument.__args__[0]  # type: ignore
                 if hasattr(type_arg, "__forward_arg__"):
@@ -1743,6 +1744,12 @@ class Relationship(
         elif hasattr(argument, "__forward_arg__"):
             argument = argument.__forward_arg__  # type: ignore
 
+            # we don't allow the collection class to be a
+            # __forward_arg__ right now, so if we see a forward arg here,
+            # we know there was no collection class either
+            if self.collection_class is None:
+                self.uselist = False
+
         self.argument = argument
 
     @util.preload_module("sqlalchemy.orm.mapper")
diff --git a/lib/sqlalchemy/orm/util.py b/lib/sqlalchemy/orm/util.py
index 317abe2b4..02080a27f 100644
--- a/lib/sqlalchemy/orm/util.py
+++ b/lib/sqlalchemy/orm/util.py
@@ -1958,8 +1958,12 @@ def _getitem(iterable_query: Query[Any], item: Any) -> Any:
 def _is_mapped_annotation(
     raw_annotation: _AnnotationScanType, cls: Type[Any]
 ) -> bool:
-    annotated = de_stringify_annotation(cls, raw_annotation)
-    return is_origin_of(annotated, "Mapped", module="sqlalchemy.orm")
+    try:
+        annotated = de_stringify_annotation(cls, raw_annotation)
+    except NameError:
+        return False
+    else:
+        return is_origin_of(annotated, "Mapped", module="sqlalchemy.orm")
 
 
 def _cleanup_mapped_str_annotation(annotation: str) -> str:
@@ -1984,7 +1988,10 @@ def _cleanup_mapped_str_annotation(annotation: str) -> str:
 
         # stack: ['Mapped', 'List', 'Address']
         if not re.match(r"""^["'].*["']$""", stack[-1]):
-            stack[-1] = f'"{stack[-1]}"'
+            stripchars = "\"' "
+            stack[-1] = ", ".join(
+                f'"{elem.strip(stripchars)}"' for elem in stack[-1].split(",")
+            )
             # stack: ['Mapped', 'List', '"Address"']
 
             annotation = "[".join(stack) + ("]" * (len(stack) - 1))
@@ -2007,6 +2014,7 @@ def _extract_mapped_subtype(
     Includes error raise scenarios and other options.
 
     """
+
     if raw_annotation is None:
 
         if required:
@@ -2017,9 +2025,19 @@ def _extract_mapped_subtype(
             )
         return None
 
-    annotated = de_stringify_annotation(
-        cls, raw_annotation, _cleanup_mapped_str_annotation
-    )
+    try:
+        annotated = de_stringify_annotation(
+            cls, raw_annotation, _cleanup_mapped_str_annotation
+        )
+    except NameError as ne:
+        if raiseerr and "Mapped[" in raw_annotation:  # type: ignore
+            raise sa_exc.ArgumentError(
+                f"Could not interpret annotation {raw_annotation}.  "
+                "Check that it's not using names that might not be imported "
+                "at the module level.  See chained stack trace for more hints."
+            ) from ne
+
+        annotated = raw_annotation  # type: ignore
 
     if is_dataclass_field:
         return annotated
diff --git a/lib/sqlalchemy/util/typing.py b/lib/sqlalchemy/util/typing.py
index 653301f1f..45fe63765 100644
--- a/lib/sqlalchemy/util/typing.py
+++ b/lib/sqlalchemy/util/typing.py
@@ -113,8 +113,10 @@ def de_stringify_annotation(
 
         try:
             annotation = eval(annotation, base_globals, None)
-        except NameError:
-            pass
+        except NameError as err:
+            raise NameError(
+                f"Could not de-stringify annotation {annotation}"
+            ) from err
     return annotation  # type: ignore