X-Git-Url: https://plomlompom.com/repos/berlin_corona.txt?a=blobdiff_plain;f=plomtask%2Fdb.py;h=13cdaef5b9c7d3e992f8c92730a9979b9eee2d73;hb=HEAD;hp=2ea7421feec578dab3fb8ba9e1eecf547eb6a36c;hpb=48ed70167c50303f46309c5808f93f2ba169b34f;p=plomtask diff --git a/plomtask/db.py b/plomtask/db.py index 2ea7421..13cdaef 100644 --- a/plomtask/db.py +++ b/plomtask/db.py @@ -4,7 +4,7 @@ from os import listdir 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 typing import Any, Self, TypeVar, Generic, Callable from plomtask.exceptions import HandledException, NotFoundException from plomtask.dating import valid_date @@ -18,8 +18,9 @@ class UnmigratedDbException(HandledException): """To identify case of unmigrated DB file.""" -class DatabaseFile: # pylint: disable=too-few-public-methods +class DatabaseFile: """Represents the sqlite3 database's file.""" + # pylint: disable=too-few-public-methods def __init__(self, path: str) -> None: self.path = path @@ -38,7 +39,7 @@ class DatabaseFile: # pylint: disable=too-few-public-methods def migrate(cls, path: str) -> DatabaseFile: """Apply migrations from_version to EXPECTED_DB_VERSION.""" migrations = cls._available_migrations() - from_version = cls.get_version_of_db(path) + from_version = cls._get_version_of_db(path) migrations_todo = migrations[from_version+1:] for j, filename in enumerate(migrations_todo): with sql_connect(path) as conn: @@ -54,7 +55,7 @@ class DatabaseFile: # pylint: disable=too-few-public-methods """Check file exists, and is of proper DB version and schema.""" if not isfile(self.path): raise NotFoundException - if self.user_version != EXPECTED_DB_VERSION: + if self._user_version != EXPECTED_DB_VERSION: raise UnmigratedDbException() self._validate_schema() @@ -86,7 +87,7 @@ class DatabaseFile: # pylint: disable=too-few-public-methods return migrations_list @staticmethod - def get_version_of_db(path: str) -> int: + def _get_version_of_db(path: str) -> int: """Get DB user_version, fail if outside expected range.""" sql_for_db_version = 'PRAGMA user_version' with sql_connect(path) as conn: @@ -99,9 +100,9 @@ class DatabaseFile: # pylint: disable=too-few-public-methods return db_version @property - def user_version(self) -> int: + def _user_version(self) -> int: """Get DB user_version.""" - 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.""" @@ -156,8 +157,7 @@ class DatabaseConnection: """A single connection to the database.""" def __init__(self, db_file: DatabaseFile) -> None: - self.file = db_file - self.conn = sql_connect(self.file.path) + self.conn = sql_connect(db_file.path) def commit(self) -> None: """Commit SQL transaction.""" @@ -167,6 +167,11 @@ class DatabaseConnection: """Add commands to SQL transaction.""" return self.conn.execute(code, inputs) + def exec_on_vals(self, code: str, inputs: tuple[Any, ...]) -> Cursor: + """Wrapper around .exec appending adequate " (?, …)" to code.""" + q_marks_from_values = '(' + ','.join(['?'] * len(inputs)) + ')' + return self.exec(f'{code} {q_marks_from_values}', inputs) + def close(self) -> None: """Close DB connection.""" self.conn.close() @@ -183,8 +188,7 @@ class DatabaseConnection: self.delete_where(table_name, key, target) for row in rows: values = tuple(row[:key_index] + [target] + row[key_index:]) - q_marks = self.__class__.q_marks_from_values(values) - self.exec(f'INSERT INTO {table_name} VALUES {q_marks}', values) + 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]: @@ -220,11 +224,6 @@ class DatabaseConnection: """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)) + ')' - BaseModelId = TypeVar('BaseModelId', int, str) BaseModelInstance = TypeVar('BaseModelInstance', bound='BaseModel[Any]') @@ -236,24 +235,36 @@ class BaseModel(Generic[BaseModelId]): to_save: list[str] = [] to_save_versioned: list[str] = [] to_save_relations: list[tuple[str, str, str, int]] = [] + add_to_dict: list[str] = [] id_: None | BaseModelId cache_: dict[BaseModelId, Self] to_search: list[str] = [] + can_create_by_id = False + _exists = True + sorters: dict[str, Callable[..., Any]] = {} 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 - 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) + return hash(self) == hash(other) def __lt__(self, other: Any) -> bool: if not isinstance(other, self.__class__): @@ -263,21 +274,115 @@ class BaseModel(Generic[BaseModelId]): assert isinstance(other.id_, int) return self.id_ < other.id_ + @property + def as_dict(self) -> dict[str, object]: + """Return self as (json.dumps-compatible) dict.""" + library: dict[str, dict[str | int, object]] = {} + d: dict[str, object] = {'id': self.id_, '_library': library} + for to_save in self.to_save: + attr = getattr(self, to_save) + if hasattr(attr, 'as_dict_into_reference'): + d[to_save] = attr.as_dict_into_reference(library) + else: + d[to_save] = attr + if len(self.to_save_versioned) > 0: + d['_versioned'] = {} + 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] + l: list[int | str] = [] + for rel in getattr(self, attr_name): + l += [rel.as_dict_into_reference(library)] + d[attr_name] = l + for k in self.add_to_dict: + d[k] = [x.as_dict_into_reference(library) + for x in getattr(self, k)] + return d + + def as_dict_into_reference(self, + library: dict[str, dict[str | int, object]] + ) -> int | str: + """Return self.id_ while writing .as_dict into library.""" + def into_library(library: dict[str, dict[str | int, object]], + cls_name: str, + id_: str | int, + d: dict[str, object] + ) -> None: + if cls_name not in library: + library[cls_name] = {} + if id_ in library[cls_name]: + if library[cls_name][id_] != d: + msg = 'Unexpected inequality of entries for ' +\ + f'_library at: {cls_name}/{id_}' + raise HandledException(msg) + else: + library[cls_name][id_] = d + as_dict = self.as_dict + assert isinstance(as_dict['_library'], dict) + for cls_name, dict_of_objs in as_dict['_library'].items(): + for id_, obj in dict_of_objs.items(): + into_library(library, cls_name, id_, obj) + del as_dict['_library'] + assert self.id_ is not None + into_library(library, self.__class__.__name__, self.id_, as_dict) + assert isinstance(as_dict['id'], (int, str)) + return as_dict['id'] + @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 name_lowercase(cls) -> str: + """Convenience method to return cls' name in lowercase.""" + return cls.__name__.lower() + + @classmethod + def sort_by(cls, seq: list[Any], sort_key: str, default: str = 'title' + ) -> str: + """Sort cls list by cls.sorters[sort_key] (reverse if '-'-prefixed).""" + reverse = False + if len(sort_key) > 1 and '-' == sort_key[0]: + sort_key = sort_key[1:] + reverse = True + if sort_key not in cls.sorters: + sort_key = default + sorter: Callable[..., Any] = cls.sorters[sort_key] + seq.sort(key=sorter, reverse=reverse) + if reverse: + sort_key = f'-{sort_key}' + return sort_key + + # 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.""" + """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 @@ -288,57 +393,91 @@ class BaseModel(Generic[BaseModelId]): 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.""" + cache = cls.get_cache() + if id_ in cache: + obj = cache[id_] + assert isinstance(obj, cls) + return obj + return None + def cache(self) -> None: - """Update object in class's cache.""" + """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 + @classmethod 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.""" + """Make from DB row (sans relations), update DB cache with it.""" obj = cls(*row) + 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 - def by_id(cls, db_conn: DatabaseConnection, - id_: BaseModelId | None, - # pylint: disable=unused-argument - create: bool = False) -> Self: + def by_id(cls, db_conn: DatabaseConnection, id_: BaseModelId) -> 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_) + 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 by_id_or_create(cls, db_conn: DatabaseConnection, + id_: BaseModelId | None + ) -> Self: + """Wrapper around .by_id, creating (not caching/saving) if not find.""" + if not cls.can_create_by_id: + raise HandledException('Class cannot .by_id_or_create.') + if id_ is None: + return cls(None) + try: + return cls.by_id(db_conn, id_) + except NotFoundException: + return cls(id_) + @classmethod def all(cls: type[BaseModelInstance], db_conn: DatabaseConnection) -> list[BaseModelInstance]: @@ -368,7 +507,7 @@ class BaseModel(Generic[BaseModelId]): date_col: str = 'day' ) -> tuple[list[BaseModelInstance], str, str]: - """Return list of Days in database within (open) date_range interval. + """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. @@ -404,6 +543,8 @@ class BaseModel(Generic[BaseModelId]): return filtered return items + # database writing + def save(self, db_conn: DatabaseConnection) -> None: """Write self to DB and cache and ensure .id_. @@ -417,10 +558,9 @@ class BaseModel(Generic[BaseModelId]): """ 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) + 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() @@ -434,11 +574,12 @@ class BaseModel(Generic[BaseModelId]): def remove(self, db_conn: DatabaseConnection) -> None: """Remove from DB and cache, including dependencies.""" - 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()