fix: Fix lazy aliased connections type resolution

RELEASE.md

@@ -0,0 +1,23 @@
+Release type: patch
+
+This release fixes an issue that would prevent using lazy aliased connections to
+annotate a connection field.
+
+For example, this should now work correctly:
+
+```python
+# types.py
+
+@strawberry.type
+class Fruit:
+    ...
+
+FruitConnection: TypeAlias = ListConnection[Fruit]
+
+
+# schema.py
+
+@strawberry.type
+class Query:
+    fruits: Annotated["FruitConnection", strawberry.lazy("types")] = strawberry.connection()
+```

strawberry/relay/fields.py

@@ -36,14 +36,15 @@
     SyncExtensionResolver,
 )
 from strawberry.field import _RESOLVER_TYPE, StrawberryField, field
+from strawberry.lazy_type import LazyType
 from strawberry.relay.exceptions import (
     RelayWrongAnnotationError,
     RelayWrongResolverAnnotationError,
 )
 from strawberry.type import StrawberryList, StrawberryOptional
 from strawberry.types.fields.resolver import StrawberryResolver
 from strawberry.utils.aio import asyncgen_to_list
-from strawberry.utils.typing import eval_type
+from strawberry.utils.typing import eval_type, is_generic_alias
 
 from .types import Connection, GlobalID, Node, NodeIterableType, NodeType
 
@@ -223,7 +224,13 @@ def apply(self, field: StrawberryField) -> None:
         ]
 
         f_type = field.type
-        if not isinstance(f_type, type) or not issubclass(f_type, Connection):
+
+        if isinstance(f_type, LazyType):
+            f_type = f_type.resolve_type()
+            field.type = f_type
+
+        type_origin = get_origin(f_type) if is_generic_alias(f_type) else f_type
+        if not isinstance(type_origin, type) or not issubclass(type_origin, Connection):
             raise RelayWrongAnnotationError(field.name, cast(type, field.origin))
 
         assert field.base_resolver
@@ -248,7 +255,7 @@ def apply(self, field: StrawberryField) -> None:
         ):
             raise RelayWrongResolverAnnotationError(field.name, field.base_resolver)
 
-        self.connection_type = cast(Type[Connection[Node]], field.type)
+        self.connection_type = cast(Type[Connection[Node]], f_type)
 
     def resolve(
         self,

strawberry/utils/typing.py

@@ -23,7 +23,7 @@
     cast,
     overload,
 )
-from typing_extensions import Annotated, get_args, get_origin
+from typing_extensions import Annotated, TypeGuard, get_args, get_origin
 
 ast_unparse = getattr(ast, "unparse", None)
 # ast.unparse is only available on python 3.9+. For older versions we will
@@ -63,15 +63,20 @@ def get_generic_alias(type_: Type) -> Type:
             continue
 
         attr = getattr(typing, attr_name)
-        # _GenericAlias overrides all the methods that we can use to know if
-        # this is a subclass of it. But if it has an "_inst" attribute
-        # then it for sure is a _GenericAlias
-        if hasattr(attr, "_inst") and attr.__origin__ is type_:
+        if is_generic_alias(attr) and attr.__origin__ is type_:
             return attr
 
     raise AssertionError(f"No GenericAlias available for {type_}")  # pragma: no cover
 
 
+def is_generic_alias(type_: Any) -> TypeGuard[_GenericAlias]:
+    """Returns True if the type is a generic alias."""
+    # _GenericAlias overrides all the methods that we can use to know if
+    # this is a subclass of it. But if it has an "_inst" attribute
+    # then it for sure is a _GenericAlias
+    return hasattr(type_, "_inst")
+
+
 def is_list(annotation: object) -> bool:
     """Returns True if annotation is a List"""
 

tests/relay/schema.py

@@ -12,7 +12,7 @@
     Optional,
     cast,
 )
-from typing_extensions import Annotated, Self
+from typing_extensions import Annotated, Self, TypeAlias
 
 import strawberry
 from strawberry import relay
@@ -191,6 +191,9 @@ async def has_permission(
         return True
 
 
+FruitsListConnectionAlias: TypeAlias = relay.ListConnection[Fruit]
+
+
 @strawberry.type
 class Query:
     node: relay.Node = relay.node()
@@ -204,6 +207,11 @@ class Query:
     fruits_lazy: relay.ListConnection[
         Annotated["Fruit", strawberry.lazy("tests.relay.schema")]
     ] = relay.connection(resolver=fruits_resolver)
+    fruits_alias: FruitsListConnectionAlias = relay.connection(resolver=fruits_resolver)
+    fruits_alias_lazy: Annotated[
+        "FruitsListConnectionAlias",
+        strawberry.lazy("tests.relay.schema"),
+    ] = relay.connection(resolver=fruits_resolver)
     fruits_async: relay.ListConnection[FruitAsync] = relay.connection(
         resolver=fruits_async_resolver
     )

tests/relay/snapshots/schema.gql

@@ -146,6 +146,32 @@ type Query {
     """Returns the items in the list that come after the specified cursor."""
     last: Int = null
   ): FruitConnection!
+  fruitsAlias(
+    """Returns the items in the list that come before the specified cursor."""
+    before: String = null
+
+    """Returns the items in the list that come after the specified cursor."""
+    after: String = null
+
+    """Returns the first n items from the list."""
+    first: Int = null
+
+    """Returns the items in the list that come after the specified cursor."""
+    last: Int = null
+  ): FruitConnection!
+  fruitsAliasLazy(
+    """Returns the items in the list that come before the specified cursor."""
+    before: String = null
+
+    """Returns the items in the list that come after the specified cursor."""
+    after: String = null
+
+    """Returns the first n items from the list."""
+    first: Int = null
+
+    """Returns the items in the list that come after the specified cursor."""
+    last: Int = null
+  ): FruitConnection!
   fruitsAsync(
     """Returns the items in the list that come before the specified cursor."""
     before: String = null

tests/relay/test_fields.py

@@ -363,6 +363,8 @@ async def test_query_nodes_optional_async():
 attrs = [
     "fruits",
     "fruitsLazy",
+    "fruitsAlias",
+    "fruitsAliasLazy",
     "fruitsConcreteResolver",
     "fruitsCustomResolver",
     "fruitsCustomResolverLazy",

tests/types/test_lazy_types.py

@@ -1,7 +1,7 @@
 # type: ignore
 import enum
 from typing import Generic, TypeVar
-from typing_extensions import Annotated
+from typing_extensions import Annotated, TypeAlias
 
 import strawberry
 from strawberry.annotation import StrawberryAnnotation
@@ -11,13 +11,23 @@
 from strawberry.types.fields.resolver import StrawberryResolver
 from strawberry.union import StrawberryUnion, union
 
+T = TypeVar("T")
+
 
 # This type is in the same file but should adequately test the logic.
 @strawberry.type
 class LaziestType:
     something: bool
 
 
+@strawberry.type
+class LazyGenericType(Generic[T]):
+    something: T
+
+
+LazyTypeAlias: TypeAlias = LazyGenericType[int]
+
+
 @strawberry.enum
 class LazyEnum(enum.Enum):
     BREAD = "BREAD"
@@ -38,6 +48,22 @@ def test_lazy_type():
     assert resolved.resolve_type() is LaziestType
 
 
+def test_lazy_type_alias():
+    # Module path is short and relative because of the way pytest runs the file
+    LazierType = LazyType("LazyTypeAlias", "test_lazy_types")
+
+    annotation = StrawberryAnnotation(LazierType)
+    resolved = annotation.resolve()
+
+    # Currently StrawberryAnnotation(LazyType).resolve() returns the unresolved
+    # LazyType. We may want to find a way to directly return the referenced object
+    # without a second resolving step.
+    assert isinstance(resolved, LazyType)
+    resolved_type = resolved.resolve_type()
+    assert resolved_type.__origin__ is LazyGenericType
+    assert resolved_type.__args__ == (int,)
+
+
 def test_lazy_type_function():
     LethargicType = Annotated["LaziestType", strawberry.lazy("test_lazy_types")]