"""Database management."""
+from __future__ import annotations
from os.path import isfile
from difflib import Differ
from sqlite3 import connect as sql_connect, Cursor, Row
-from typing import Any, Dict
-from plomtask.exceptions import HandledException
+from typing import Any, Self, TypeVar, Generic
+from plomtask.exceptions import HandledException, NotFoundException
PATH_DB_SCHEMA = 'scripts/init.sql'
+EXPECTED_DB_VERSION = 0
class DatabaseFile: # pylint: disable=too-few-public-methods
self._check()
def _check(self) -> None:
- """Check file exists, and is of proper schema."""
+ """Check file exists, and is of proper DB version and schema."""
self.exists = isfile(self.path)
if self.exists:
+ self._validate_user_version()
self._validate_schema()
+ def _validate_user_version(self) -> None:
+ """Compare DB user_version with EXPECTED_DB_VERSION."""
+ sql_for_db_version = 'PRAGMA user_version'
+ with sql_connect(self.path) as conn:
+ db_version = list(conn.execute(sql_for_db_version))[0][0]
+ if db_version != EXPECTED_DB_VERSION:
+ msg = f'Wrong DB version, expected '\
+ f'{EXPECTED_DB_VERSION}, got {db_version}.'
+ raise HandledException(msg)
+
def _validate_schema(self) -> None:
"""Compare found schema with what's stored at PATH_DB_SCHEMA."""
sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
def __init__(self, db_file: DatabaseFile) -> None:
self.file = db_file
self.conn = sql_connect(self.file.path)
- self.cached_todos: Dict[int, Any] = {}
- self.cached_days: Dict[str, Any] = {}
- self.cached_process_steps: Dict[int, Any] = {}
- self.cached_processes: Dict[int, Any] = {}
- self.cached_conditions: Dict[int, Any] = {}
def commit(self) -> None:
"""Commit SQL transaction."""
"""Close DB connection."""
self.conn.close()
+ 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 | str) -> None:
+ """Delete from table where key == target."""
+ self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
-class BaseModel:
+ @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]')
+
+
+class BaseModel(Generic[BaseModelId]):
"""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
+ id_: None | BaseModelId
+ cache_: dict[BaseModelId, Self]
+
+ 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_
+
+ 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)
+
+ 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_
+
+ @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
@classmethod
- def from_table_row(cls, db_conn: DatabaseConnection,
- row: Row | list[Any]) -> Any:
+ 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.')
+ 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.')
+ cache = self.__class__.get_cache()
+ del cache[self.id_]
+
+ @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."""
obj = cls(*row)
- assert isinstance(obj.id_, cls.id_type)
- cache = getattr(db_conn, f'cached_{cls.table_name}')
- cache[obj.id_] = obj
+ obj.cache()
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
+ 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
- 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.exec(f'SELECT * FROM {cls.table_name} '
- 'WHERE 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_
+ 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.
- def save_core(self, db_conn: DatabaseConnection,
- update_with_lastrowid: bool = True) -> None:
- """Write bare-bones self (sans connected items), ensuring self.id_."""
- q_marks = ','.join(['?'] * (len(self.to_save) + 1))
+ 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 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})',
+ 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
+ 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."""
+ if self.id_ is None or self.__class__.get_cached(self.id_) is None:
+ raise HandledException('cannot remove unsaved item')
+ self.uncache()
+ db_conn.delete_where(self.table_name, 'id', self.id_)
projects / plomtask / blobdiff