Fix bug of same dict being used for different Classes' caches.

diff --git a/plomtask/db.py b/plomtask/db.py
index 2d9ae2714ca9a2e625036ea44f295880db986f16..1753da43cee71ca2204bbbdfd27c69aa52bd93fe 100644 (file)
--- a/plomtask/db.py
+++ b/plomtask/db.py
@@ -121,7 +121,7 @@ class BaseModel(Generic[BaseModelId]):
     table_name = ''
     to_save: list[str] = []
     id_: None | BaseModelId
-    cache_: dict[BaseModelId, Self] = {}
+    cache_: dict[BaseModelId, Self]
 
     @classmethod
     def from_table_row(cls: type[BaseModelInstance],
@@ -174,8 +174,9 @@ class BaseModel(Generic[BaseModelId]):
                    id_: BaseModelId) -> BaseModelInstance | None:
         """Get object of id_ from class's cache, or None if not found."""
         # pylint: disable=consider-iterating-dictionary
-        if id_ in cls.cache_.keys():
-            obj = cls.cache_[id_]
+        cache = cls.get_cache()
+        if id_ in cache.keys():
+            obj = cache[id_]
             assert isinstance(obj, cls)
             return obj
         return None
@@ -184,13 +185,15 @@ class BaseModel(Generic[BaseModelId]):
         """Update object in class's cache."""
         if self.id_ is None:
             raise HandledException('Cannot cache object without ID.')
-        self.__class__.cache_[self.id_] = self
+        cache = self.__class__.get_cache()
+        cache[self.id_] = self
 
     def uncache(self) -> None:
         """Remove self from cache."""
         if self.id_ is None:
             raise HandledException('Cannot un-cache object without ID.')
-        del self.__class__.cache_[self.id_]
+        cache = self.__class__.get_cache()
+        del cache[self.id_]
 
     @classmethod
     def empty_cache(cls) -> None:
@@ -202,7 +205,7 @@ class BaseModel(Generic[BaseModelId]):
             db_conn: DatabaseConnection) -> list[BaseModelInstance]:
         """Collect all objects of class."""
         items: dict[BaseModelId, BaseModelInstance] = {}
-        for k, v in cls.cache_.items():
+        for k, v in cls.get_cache().items():
             assert isinstance(v, cls)
             items[k] = v
         already_recorded = items.keys()
@@ -212,3 +215,11 @@ class BaseModel(Generic[BaseModelId]):
                 item = cls.by_id(db_conn, id_)  # type: ignore[attr-defined]
                 items[item.id_] = item
         return list(items.values())
+
+    @classmethod
+    def get_cache(cls: type[BaseModelInstance]) -> dict[Any, BaseModel[Any]]:
+        """Get cache dictionary, create it if not yet existing."""
+        if not hasattr(cls, 'cache_'):
+            d: dict[Any, BaseModel[Any]] = {}
+            cls.cache_ = d
+        return cls.cache_