X-Git-Url: https://plomlompom.com/repos/feed.xml?a=blobdiff_plain;f=plomtask%2Fdb.py;h=3a661d37758f579a9cac09dc90b86f07f0572e04;hb=a0244482692edf794960f3c2af9461be2ad15e8a;hp=bf2b79f758b313525816581620a792330fdbd9a2;hpb=23c7ff7f9833ff5b0e547c19a4ad85325a5d3400;p=plomtask diff --git a/plomtask/db.py b/plomtask/db.py index bf2b79f..3a661d3 100644 --- a/plomtask/db.py +++ b/plomtask/db.py @@ -4,7 +4,7 @@ from os.path import isfile from difflib import Differ from sqlite3 import connect as sql_connect, Cursor, Row from typing import Any, Self, TypeVar, Generic -from plomtask.exceptions import HandledException +from plomtask.exceptions import HandledException, NotFoundException PATH_DB_SCHEMA = 'scripts/init.sql' EXPECTED_DB_VERSION = 0 @@ -102,7 +102,8 @@ class DatabaseConnection: 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: + 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,)) @@ -112,86 +113,154 @@ class DatabaseConnection: return '(' + ','.join(['?'] * len(values)) + ')' -X = TypeVar('X', int, str) -T = TypeVar('T', bound='BaseModel[Any]') +BaseModelId = TypeVar('BaseModelId', int, str) +BaseModelInstance = TypeVar('BaseModelInstance', bound='BaseModel[Any]') -class BaseModel(Generic[X]): +class BaseModel(Generic[BaseModelId]): """Template for most of the models we use/derive from the DB.""" table_name = '' to_save: list[str] = [] - id_: None | X - cache_: dict[X, Self] = {} + id_: None | BaseModelId + cache_: dict[BaseModelId, Self] - @classmethod - def from_table_row(cls: type[T], - # pylint: disable=unused-argument - db_conn: DatabaseConnection, - row: Row | list[Any]) -> T: - """Make from DB row, write to DB cache.""" - obj = cls(*row) - obj.cache() - return obj - - @classmethod - def _by_id(cls, - db_conn: DatabaseConnection, - id_: X) -> tuple[Self | None, bool]: - """Return instance found by ID, or None, and if from cache or not.""" - from_cache = False - obj = cls.get_cached(id_) - if obj: - from_cache = True - else: - for row in db_conn.row_where(cls.table_name, 'id', id_): - obj = cls.from_table_row(db_conn, row) - obj.cache() - 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: + 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) - self.id_ = id_ # type: ignore[assignment] - - 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 # type: ignore[assignment] - self.cache() + self.id_ = id_ @classmethod - def get_cached(cls: type[T], id_: X) -> T | None: + 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 - 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 + @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.""" 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: - """Empty class's cache.""" - cls.cache_ = {} + def from_table_row(cls: type[BaseModelInstance], + # pylint: disable=unused-argument + db_conn: DatabaseConnection, + row: Row | list[Any]) -> BaseModelInstance: + """Make from DB row, write to DB cache.""" + 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) + obj.cache() + 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()) + + def __eq__(self, other: object) -> bool: + if not isinstance(other, self.__class__): + msg = 'cannot compare to object of different class' + raise HandledException(msg) + to_hash_me = tuple([self.id_] + + [getattr(self, name) for name in self.to_save]) + to_hash_other = tuple([other.id_] + + [getattr(other, name) for name in other.to_save]) + return hash(to_hash_me) == hash(to_hash_other) + + def save_core(self, db_conn: DatabaseConnection) -> None: + """Write bare-bones self (sans connected items), ensuring self.id_. + + Write both to DB, and to cache. To DB, write .id_ and attributes + listed in cls.to_save. + + 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]) + 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 not isinstance(self.id_, str): + self.id_ = cursor.lastrowid # type: ignore[assignment] + self.cache() + + def remove(self, db_conn: DatabaseConnection) -> None: + """Remove from DB and cache.""" + assert isinstance(self.id_, int | str) + self.uncache() + db_conn.delete_where(self.table_name, 'id', self.id_)