"""Database management."""
+from __future__ import annotations
from os.path import isfile
from difflib import Differ
-from sqlite3 import connect as sql_connect
-from plomtask.misc import HandledException
+from sqlite3 import connect as sql_connect, Cursor, Row
+from typing import Any, Self, TypeVar, Generic
+from plomtask.exceptions import HandledException
PATH_DB_SCHEMA = 'scripts/init.sql'
+EXPECTED_DB_VERSION = 0
class DatabaseFile: # pylint: disable=too-few-public-methods
"""Represents the sqlite3 database's file."""
- def __init__(self, path):
+ def __init__(self, path: str) -> None:
self.path = path
self._check()
- def remake(self):
+ def remake(self) -> None:
"""Create tables in self.path file as per PATH_DB_SCHEMA sql file."""
with sql_connect(self.path) as conn:
with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
conn.executescript(f.read())
self._check()
- def _check(self):
- """Check file exists and is of proper schema."""
+ def _check(self) -> None:
+ """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_schema(self):
+ 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'
msg_err = 'Database has wrong tables schema. Diff:\n'
class DatabaseConnection:
"""A single connection to the database."""
- def __init__(self, db_file: DatabaseFile):
+ def __init__(self, db_file: DatabaseFile) -> None:
self.file = db_file
self.conn = sql_connect(self.file.path)
- def commit(self):
+ def commit(self) -> None:
"""Commit SQL transaction."""
self.conn.commit()
- def exec(self, code: str, inputs: tuple = ()):
+ def exec(self, code: str, inputs: tuple[Any, ...] = tuple()) -> Cursor:
"""Add commands to SQL transaction."""
return self.conn.execute(code, inputs)
- def close(self):
+ def close(self) -> None:
"""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) -> 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)) + ')'
+
+
+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 | BaseModelId
+ cache_: dict[BaseModelId, Self] = {}
+
+ @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)
+ obj.cache()
+ return obj
+
+ @classmethod
+ def _by_id(cls,
+ db_conn: DatabaseConnection,
+ id_: BaseModelId) -> 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:
+ 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()
+
+ @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
+ if id_ in cls.cache_.keys():
+ obj = cls.cache_[id_]
+ assert isinstance(obj, cls)
+ return obj
+ return None
+
+ 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
+
+ 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_]
+
+ @classmethod
+ def empty_cache(cls) -> None:
+ """Empty class's cache."""
+ cls.cache_ = {}
+
+ @classmethod
+ def all(cls: type[BaseModelInstance],
+ db_conn: DatabaseConnection) -> list[BaseModelInstance]:
+ """Collect all objects of class."""
+ items: dict[BaseModelId, BaseModelInstance] = {}
+ for k, v in cls.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:
+ # pylint: disable=no-member
+ item = cls.by_id(db_conn, id_) # type: ignore[attr-defined]
+ items[item.id_] = item
+ return list(items.values())
projects / plomtask / blobdiff