Add endpoint to get all event categories

src/api/categories.py

@@ -125,6 +125,22 @@ async def get_user_categories(user_id: PydanticObjectId, user: CurrentUserDep) -
     return [CategoryData.from_category(category) for category in categories]
 
 
+@base_router.get("/events/{event_id}/categories")
+async def get_event_categories(event_id: PydanticObjectId, user: CurrentUserDep) -> list[CategoryData]:
+    """Get all categories that belong to given event."""
+    event = await Event.get(event_id, fetch_links=True)
+    if event is None:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Event with given id doesn't exist")
+
+    if cast(User, event.user).id != user.id:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="You can only access your own events",
+        )
+
+    return [CategoryData.from_category(category) for category in cast(list[Category], event.categories)]
+
+
 @categories_router.get("{category_id}")
 async def get_category(category_id: PydanticObjectId, user: CurrentUserDep) -> CategoryData:
     """Get a category by ID."""