Fix cache schema directive class to support Strawberry >= 0.326.0 (#949)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Thiago Bellini Ribeiro <hackedbellini@gmail.com>

Author: 4 people

RELEASE.md

@@ -0,0 +1,33 @@
+---
+release type: patch
+---
+
+Permission extensions are now fully compatible with `strawberry-graphql >= 0.326.0`, which enforces strict type uniqueness for custom schema directives during schema construction.
+
+Previously, `DjangoPermissionExtension.schema_directive` created a new anonymous `AutoDirective` class on every extension instantiation without caching it on the underlying class.
+When the same permission extension (e.g. `IsSuperuser()`, `IsAuthenticated()`, or custom subclasses) was attached to multiple fields, Strawberry raised a `ValueError` reporting duplicate directive definitions for the same directive name.
+
+The generated `AutoDirective` class is now cached on `self.__class__` via `__dict__.get()`:
+
+```python
+@functools.cached_property
+def schema_directive(self) -> object:
+    key = "__strawberry_directive_type__"
+    directive_class = self.__class__.__dict__.get(key)
+
+    if directive_class is None:
+        @schema_directive(
+            name=self.__class__.__name__,
+            locations=self.SCHEMA_DIRECTIVE_LOCATIONS,
+            description=self.SCHEMA_DIRECTIVE_DESCRIPTION,
+            repeatable=True,
+        )
+        class AutoDirective: ...
+
+        directive_class = AutoDirective
+        setattr(self.__class__, key, directive_class)
+
+    return directive_class()
+```
+
+This ensures a single, reusable schema directive type is created per extension class, eliminating duplicate directive collisions while preserving full isolation across subclasses and maintaining backward compatibility with older Strawberry versions.

strawberry_django/permissions.py

@@ -280,7 +280,7 @@ def apply(self, field: StrawberryField) -> None:  # pragma: no cover
     @functools.cached_property
     def schema_directive(self) -> object:
         key = "__strawberry_directive_type__"
-        directive_class = getattr(self.__class__, key, None)
+        directive_class = self.__class__.__dict__.get(key)
 
         if directive_class is None:
 
@@ -293,6 +293,7 @@ def schema_directive(self) -> object:
             class AutoDirective: ...
 
             directive_class = AutoDirective
+            setattr(self.__class__, key, directive_class)
 
         return directive_class()
 
@@ -692,7 +693,7 @@ def __init__(
     @functools.cached_property
     def schema_directive(self) -> object:
         key = "__strawberry_directive_class__"
-        directive_class = getattr(self.__class__, key, None)
+        directive_class = self.__class__.__dict__.get(key)
 
         if directive_class is None:
 
@@ -713,6 +714,7 @@ class AutoDirective:
                 )
 
             directive_class = AutoDirective
+            setattr(self.__class__, key, directive_class)
 
         return directive_class(
             permissions=list(self.perms),