+
+ def rewrite_relations(self, table_name: str, key: str, target: int,
+ rows: list[list[Any]]) -> None:
+ """Rewrite relations in table_name to target, with rows values."""
+ self.delete_where(table_name, key, target)
+ for row in rows:
+ values = tuple([target] + row)
+ q_marks = self.__class__.q_marks_from_values(values)
+ self.exec(f'INSERT INTO {table_name} VALUES {q_marks}', 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(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) -> None:
+ """Delete from table where key == target."""
+ self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
+
+ @staticmethod
+ def q_marks_from_values(values: tuple[Any]) -> str:
+ """Return placeholder to insert values into SQL code."""
+ return '(' + ','.join(['?'] * len(values)) + ')'
+
+
+class BaseModel:
+ """Template for most of the models we use/derive from the DB."""
+ table_name = ''
+ to_save: list[str] = []
+ id_: None | int | str
+ id_type: type[Any] = int
+
+ @classmethod
+ def from_table_row(cls, db_conn: DatabaseConnection,
+ row: Row | list[Any]) -> Any:
+ """Make from DB row, write to DB cache."""
+ obj = cls(*row)
+ assert isinstance(obj.id_, cls.id_type)
+ cache = getattr(db_conn, f'cached_{cls.table_name}')
+ cache[obj.id_] = obj
+ return obj
+
+ @classmethod
+ def _by_id(cls,
+ db_conn: DatabaseConnection,
+ id_: int | str) -> tuple[Any, bool]:
+ """Return instance found by ID, or None, and if from cache or not."""
+ from_cache = False
+ obj = None
+ cache = getattr(db_conn, f'cached_{cls.table_name}')
+ if id_ in cache.keys():
+ obj = cache[id_]
+ from_cache = True
+ else:
+ for row in db_conn.row_where(cls.table_name, 'id', id_):
+ obj = cls.from_table_row(db_conn, row)
+ cache[id_] = obj
+ break
+ return obj, from_cache
+
+ def set_int_id(self, id_: int | None) -> None:
+ """Set id_ if >= 1 or None, else fail."""
+ if (id_ is not None) and id_ < 1:
+ msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
+ raise HandledException(msg)
+ self.id_ = id_
+
+ def save_core(self, db_conn: DatabaseConnection,
+ update_with_lastrowid: bool = True) -> None:
+ """Write bare-bones self (sans connected items), ensuring self.id_."""
+ values = tuple([self.id_] + [getattr(self, key)
+ for key in self.to_save])
+ q_marks = DatabaseConnection.q_marks_from_values(values)
+ table_name = self.table_name
+ cursor = db_conn.exec(f'REPLACE INTO {table_name} VALUES {q_marks}',
+ values)
+ if update_with_lastrowid:
+ self.id_ = cursor.lastrowid
+ cache = getattr(db_conn, f'cached_{table_name}')
+ cache[self.id_] = self