+
+ def rewrite_relations(self, table_name: str, key: str, target: int | str,
+ rows: list[list[Any]], key_index: int = 0) -> None:
+ # pylint: disable=too-many-arguments
+ """Rewrite relations in table_name to target, with rows values.
+
+ Note that single rows are expected without the column and value
+ identified by key and target, which are inserted inside the function
+ at key_index.
+ """
+ self.delete_where(table_name, key, target)
+ for row in rows:
+ values = tuple(row[:key_index] + [target] + row[key_index:])
+ self.exec_on_vals(f'INSERT INTO {table_name} VALUES', values)
+
+ def row_where(self, table_name: str, key: str,
+ target: int | str) -> list[Row]:
+ """Return list of Rows at table where key == target."""
+ return list(self.exec(f'SELECT * FROM {table_name} WHERE {key} = ?',
+ (target,)))
+
+ # def column_where_pattern(self,
+ # table_name: str,
+ # column: str,
+ # pattern: str,
+ # keys: list[str]) -> list[Any]:
+ # """Return column of rows where one of keys matches pattern."""
+ # targets = tuple([f'%{pattern}%'] * len(keys))
+ # haystack = ' OR '.join([f'{k} LIKE ?' for k in keys])
+ # sql = f'SELECT {column} FROM {table_name} WHERE {haystack}'
+ # return [row[0] for row in self.exec(sql, targets)]
+
+ def column_where(self, table_name: str, column: str, key: str,
+ target: int | str) -> list[Any]:
+ """Return column of table where key == target."""
+ return [row[0] for row in
+ self.exec(f'SELECT {column} FROM {table_name} '
+ f'WHERE {key} = ?', (target,))]
+
+ def column_all(self, table_name: str, column: str) -> list[Any]:
+ """Return complete column of table."""
+ return [row[0] for row in
+ self.exec(f'SELECT {column} FROM {table_name}')]
+
+ def delete_where(self, table_name: str, key: str,
+ target: int | str) -> None:
+ """Delete from table where key == target."""
+ self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
+
+
+BaseModelId = TypeVar('BaseModelId', int, str)
+BaseModelInstance = TypeVar('BaseModelInstance', bound='BaseModel[Any]')
+
+
+class BaseModel(Generic[BaseModelId]):
+ """Template for most of the models we use/derive from the DB."""
+ table_name = ''
+ to_save: list[str] = []
+ to_save_versioned: list[str] = []
+ to_save_relations: list[tuple[str, str, str, int]] = []
+ 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:
+ msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
+ raise HandledException(msg)
+ if isinstance(id_, str) and "" == id_:
+ msg = f'illegal {self.__class__.__name__} ID, must be non-empty'
+ raise HandledException(msg)
+ self.id_ = id_
+
+ def __hash__(self) -> int:
+ hashable = [self.id_] + [getattr(self, name) for name in self.to_save]
+ for definition in self.to_save_relations:
+ attr = getattr(self, definition[2])
+ hashable += [tuple(rel.id_ for rel in attr)]
+ for name in self.to_save_versioned:
+ hashable += [hash(getattr(self, name))]
+ return hash(tuple(hashable))
+
+ def __eq__(self, other: object) -> bool:
+ if not isinstance(other, self.__class__):
+ return False
+ return hash(self) == hash(other)
+
+ def __lt__(self, other: Any) -> bool:
+ if not isinstance(other, self.__class__):
+ msg = 'cannot compare to object of different class'
+ raise HandledException(msg)
+ assert isinstance(self.id_, int)
+ 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."""
+ 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],
+ id_: BaseModelId) -> BaseModelInstance | None:
+ """Get object of id_ from class's cache, or None if not found."""
+ # pylint: disable=consider-iterating-dictionary
+ cache = cls.get_cache()
+ if id_ in cache.keys():
+ obj = cache[id_]
+ assert isinstance(obj, cls)
+ return obj
+ return None
+
+ 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.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:
+ """Remove self from cache."""
+ if self.id_ is None:
+ raise HandledException('Cannot un-cache object without ID.')
+ cache = self.get_cache()
+ del cache[self.id_]
+
+ # object retrieval and generation
+
+ @classmethod
+ def from_table_row(cls: type[BaseModelInstance],
+ # pylint: disable=unused-argument
+ db_conn: DatabaseConnection,
+ row: Row | list[Any]) -> BaseModelInstance:
+ """Make from DB row, update DB cache with it."""
+ obj = cls(*row)
+ obj._cache()
+ return obj
+
+ @classmethod
+ def by_id(cls, db_conn: DatabaseConnection,
+ id_: BaseModelId | None,
+ # pylint: disable=unused-argument
+ create: bool = False) -> Self:
+ """Retrieve by id_, on failure throw NotFoundException.
+
+ First try to get from cls.cache_, only then check DB; if found,
+ put into cache.
+
+ If create=True, make anew (but do not cache yet).
+ """
+ obj = None
+ if id_ is not None:
+ obj = cls._get_cached(id_)
+ if not obj:
+ for row in db_conn.row_where(cls.table_name, 'id', id_):
+ obj = cls.from_table_row(db_conn, row)
+ break
+ if obj:
+ return obj
+ if create:
+ obj = cls(id_)
+ return obj
+ raise NotFoundException(f'found no object of ID {id_}')
+
+ @classmethod
+ def all(cls: type[BaseModelInstance],
+ db_conn: DatabaseConnection) -> list[BaseModelInstance]:
+ """Collect all objects of class into list.
+
+ Note that this primarily returns the contents of the cache, and only
+ _expands_ that by additional findings in the DB. This assumes the
+ cache is always instantly cleaned of any items that would be removed
+ from the DB.
+ """
+ items: dict[BaseModelId, BaseModelInstance] = {}
+ for k, v in cls.get_cache().items():
+ assert isinstance(v, cls)
+ items[k] = v
+ already_recorded = items.keys()
+ for id_ in db_conn.column_all(cls.table_name, 'id'):
+ if id_ not in already_recorded:
+ item = cls.by_id(db_conn, id_)
+ assert item.id_ is not None
+ items[item.id_] = item
+ return list(items.values())
+
+ @classmethod
+ def by_date_range_with_limits(cls: type[BaseModelInstance],
+ db_conn: DatabaseConnection,
+ date_range: tuple[str, str],
+ date_col: str = 'day'
+ ) -> tuple[list[BaseModelInstance], str,
+ str]:
+ """Return list of items in database within (open) date_range interval.
+
+ If no range values provided, defaults them to 'yesterday' and
+ 'tomorrow'. Knows to properly interpret these and 'today' as value.
+ """
+ start_str = date_range[0] if date_range[0] else 'yesterday'
+ end_str = date_range[1] if date_range[1] else 'tomorrow'
+ start_date = valid_date(start_str)
+ end_date = valid_date(end_str)
+ items = []
+ sql = f'SELECT id FROM {cls.table_name} '
+ sql += f'WHERE {date_col} >= ? AND {date_col} <= ?'
+ for row in db_conn.exec(sql, (start_date, end_date)):
+ items += [cls.by_id(db_conn, row[0])]
+ return items, start_date, end_date
+
+ @classmethod
+ def matching(cls: type[BaseModelInstance], db_conn: DatabaseConnection,
+ pattern: str) -> list[BaseModelInstance]:
+ """Return all objects whose .to_search match pattern."""
+ items = cls.all(db_conn)
+ if pattern:
+ filtered = []
+ for item in items:
+ for attr_name in cls.to_search:
+ toks = attr_name.split('.')
+ parent = item
+ for tok in toks:
+ attr = getattr(parent, tok)
+ parent = attr
+ if pattern in attr:
+ filtered += [item]
+ break
+ return filtered
+ return items
+
+ # database writing
+
+ def save(self, db_conn: DatabaseConnection) -> None:
+ """Write self to DB and cache and ensure .id_.
+
+ Write both to DB, and to cache. To DB, write .id_ and attributes
+ listed in cls.to_save[_versioned|_relations].
+
+ Ensure self.id_ by setting it to what the DB command returns as the
+ last saved row's ID (cursor.lastrowid), EXCEPT if self.id_ already
+ exists as a 'str', which implies we do our own ID creation (so far
+ only the case with the Day class, where it's to be a date string.
+ """
+ values = tuple([self.id_] + [getattr(self, key)
+ for key in self.to_save])
+ table_name = self.table_name
+ cursor = db_conn.exec_on_vals(f'REPLACE INTO {table_name} VALUES',
+ values)
+ if not isinstance(self.id_, str):
+ self.id_ = cursor.lastrowid # type: ignore[assignment]
+ 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:
+ assert isinstance(self.id_, (int, str))
+ db_conn.rewrite_relations(table, column, self.id_,
+ [[i.id_] for i
+ in getattr(self, attr_name)], key_index)
+
+ def remove(self, db_conn: DatabaseConnection) -> None:
+ """Remove from DB and cache, including dependencies."""
+ 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()
+ db_conn.delete_where(self.table_name, 'id', self.id_)
+ self._disappear()