@property
def _user_version(self) -> int:
"""Get DB user_version."""
- # pylint: disable=protected-access
- # (since we remain within class)
- return self.__class__._get_version_of_db(self.path)
+ return self._get_version_of_db(self.path)
def _validate_schema(self) -> None:
"""Compare found schema with what's stored at PATH_DB_SCHEMA."""
id_: None | BaseModelId
cache_: dict[BaseModelId, Self]
to_search: list[str] = []
+ _exists = True
def __init__(self, id_: BaseModelId | None) -> None:
if isinstance(id_, int) and id_ < 1:
assert isinstance(other.id_, int)
return self.id_ < other.id_
+ @property
+ def as_dict(self) -> dict[str, object]:
+ """Return self as (json.dumps-coompatible) dict."""
+ d: dict[str, object] = {'id': self.id_}
+ if len(self.to_save_versioned) > 0:
+ d['_versioned'] = {}
+ for k in self.to_save:
+ attr = getattr(self, k)
+ if hasattr(attr, 'as_dict'):
+ d[k] = attr.as_dict
+ d[k] = attr
+ for k in self.to_save_versioned:
+ attr = getattr(self, k)
+ assert isinstance(d['_versioned'], dict)
+ d['_versioned'][k] = attr.history
+ for r in self.to_save_relations:
+ attr_name = r[2]
+ d[attr_name] = [x.as_dict for x in getattr(self, attr_name)]
+ return d
+
# cache management
+ # (we primarily use the cache to ensure we work on the same object in
+ # memory no matter where and how we retrieve it, e.g. we don't want
+ # .by_id() calls to create a new object each time, but rather a pointer
+ # to the one already instantiated)
+
+ def __getattribute__(self, name: str) -> Any:
+ """Ensure fail if ._disappear() was called, except to check ._exists"""
+ if name != '_exists' and not super().__getattribute__('_exists'):
+ raise HandledException('Object does not exist.')
+ return super().__getattribute__(name)
+
+ def _disappear(self) -> None:
+ """Invalidate object, make future use raise exceptions."""
+ assert self.id_ is not None
+ if self._get_cached(self.id_):
+ self._uncache()
+ to_kill = list(self.__dict__.keys())
+ for attr in to_kill:
+ delattr(self, attr)
+ self._exists = False
+
+ @classmethod
+ def empty_cache(cls) -> None:
+ """Empty class's cache, and disappear all former inhabitants."""
+ # pylint: disable=protected-access
+ # (cause we remain within the class)
+ if hasattr(cls, 'cache_'):
+ to_disappear = list(cls.cache_.values())
+ for item in to_disappear:
+ item._disappear()
+ cls.cache_ = {}
+
+ @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_
@classmethod
def _get_cached(cls: type[BaseModelInstance],
return obj
return None
- @classmethod
- def empty_cache(cls) -> None:
- """Empty class's cache."""
- cls.cache_ = {}
-
- @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_
+ def _cache(self) -> None:
+ """Update object in class's cache.
- def cache(self) -> None:
- """Update object in class's cache."""
+ Also calls ._disappear if cache holds older reference to object of same
+ ID, but different memory address, to avoid doing anything with
+ dangling leftovers.
+ """
if self.id_ is None:
raise HandledException('Cannot cache object without ID.')
- cache = self.__class__.get_cache()
+ cache = self.get_cache()
+ old_cached = self._get_cached(self.id_)
+ if old_cached and id(old_cached) != id(self):
+ # pylint: disable=protected-access
+ # (cause we remain within the class)
+ old_cached._disappear()
cache[self.id_] = self
- def uncache(self) -> None:
+ def _uncache(self) -> None:
"""Remove self from cache."""
if self.id_ is None:
raise HandledException('Cannot un-cache object without ID.')
- cache = self.__class__.get_cache()
+ cache = self.get_cache()
del cache[self.id_]
# object retrieval and generation
# pylint: disable=unused-argument
db_conn: DatabaseConnection,
row: Row | list[Any]) -> BaseModelInstance:
- """Make from DB row, write to DB cache."""
+ """Make from DB row (sans relations), update DB cache with it."""
obj = cls(*row)
- obj.cache()
+ assert obj.id_ is not None
+ for attr_name in cls.to_save_versioned:
+ attr = getattr(obj, attr_name)
+ table_name = attr.table_name
+ for row_ in db_conn.row_where(table_name, 'parent', obj.id_):
+ attr.history_from_row(row_)
+ obj._cache()
return obj
@classmethod
if not obj:
for row in db_conn.row_where(cls.table_name, 'id', id_):
obj = cls.from_table_row(db_conn, row)
- obj.cache()
break
if obj:
return obj
values)
if not isinstance(self.id_, str):
self.id_ = cursor.lastrowid # type: ignore[assignment]
- self.cache()
+ self._cache()
for attr_name in self.to_save_versioned:
getattr(self, attr_name).save(db_conn)
for table, column, attr_name, key_index in self.to_save_relations:
def remove(self, db_conn: DatabaseConnection) -> None:
"""Remove from DB and cache, including dependencies."""
- # pylint: disable=protected-access
- # (since we remain within class)
- if self.id_ is None or self.__class__._get_cached(self.id_) is None:
+ if self.id_ is None or self._get_cached(self.id_) is None:
raise HandledException('cannot remove unsaved item')
for attr_name in self.to_save_versioned:
getattr(self, attr_name).remove(db_conn)
for table, column, attr_name, _ in self.to_save_relations:
db_conn.delete_where(table, column, self.id_)
- self.uncache()
+ self._uncache()
db_conn.delete_where(self.table_name, 'id', self.id_)
+ self._disappear()