feat: context key property for new container locator keys

opaque_keys/edx/django/models.py

@@ -3,6 +3,7 @@
 If Django is unavailable, none of the classes below will work as intended.
 """
 from __future__ import annotations
+
 import logging
 import warnings
 
@@ -17,8 +18,7 @@
     IsNull = object
 
 from opaque_keys import OpaqueKey
-from opaque_keys.edx.keys import BlockTypeKey, CourseKey, LearningContextKey, UsageKey
-
+from opaque_keys.edx.keys import BlockTypeKey, CourseKey, LearningContextKey, LibraryItemKey, UsageKey
 
 log = logging.getLogger(__name__)
 
@@ -224,6 +224,17 @@ class UsageKeyField(OpaqueKeyField):
     _pyi_private_get_type: UsageKey | None
 
 
+class LibraryItemField(OpaqueKeyField):
+    """
+    A django Field that stores a LibraryItemKey object as a string.
+    """
+    description = "A Location object, saved to the DB in the form of a string"
+    KEY_CLASS = LibraryItemKey
+    # Declare the field types for the django-stubs mypy type hint plugin:
+    _pyi_private_set_type: LibraryItemKey | str | None
+    _pyi_private_get_type: LibraryItemKey | None
+
+
 class LocationKeyField(UsageKeyField):
     """
     A django Field that stores a UsageKey object as a string.

opaque_keys/edx/keys.py

@@ -114,6 +114,15 @@
     def library_key(self):
         return self.lib_key
 
+    @property
+    @abstractmethod
+    def context_key(self) -> LearningContextKey:
+        """
+        Get the learning context key (LearningContextKey) for this XBlock usage.
+        May be a course key, library key, or some other LearningContextKey type.
+        """
+        raise NotImplementedError()
+
 
 class DefinitionKey(OpaqueKey):
     """

opaque_keys/edx/locator.py

@@ -1675,6 +1675,10 @@
         except (ValueError, TypeError) as error:
             raise InvalidKeyError(cls, serialized) from error
 
+    @property
+    def context_key(self) -> LibraryLocatorV2:
+        return self.lib_key
+
 
 class LibraryContainerLocator(CheckFieldMixin, LibraryItemKey):
     """
@@ -1714,6 +1718,10 @@
         """
         return self.lib_key.org
 
+    @property
+    def context_key(self) -> LibraryLocatorV2:
+        return self.lib_key
+
     def _to_string(self) -> str:
         """
         Serialize this key as a string