plomlompom.com Git - plomtask/blob - plomtask/db.py

   1 """Database management."""
   2 from __future__ import annotations
   3 from os import listdir
   4 from os.path import isfile
   5 from difflib import Differ
   6 from sqlite3 import connect as sql_connect, Cursor, Row
   7 from typing import Any, Self, TypeVar, Generic
   8 from plomtask.exceptions import HandledException, NotFoundException
   9 from plomtask.dating import valid_date
  10
  11 EXPECTED_DB_VERSION = 5
  12 MIGRATIONS_DIR = 'migrations'
  13 FILENAME_DB_SCHEMA = f'init_{EXPECTED_DB_VERSION}.sql'
  14 PATH_DB_SCHEMA = f'{MIGRATIONS_DIR}/{FILENAME_DB_SCHEMA}'
  15
  16
  17 class UnmigratedDbException(HandledException):
  18     """To identify case of unmigrated DB file."""
  19
  20
  21 class DatabaseFile:
  22     """Represents the sqlite3 database's file."""
  23     # pylint: disable=too-few-public-methods
  24
  25     def __init__(self, path: str) -> None:
  26         self.path = path
  27         self._check()
  28
  29     @classmethod
  30     def create_at(cls, path: str) -> DatabaseFile:
  31         """Make new DB file at path."""
  32         with sql_connect(path) as conn:
  33             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
  34                 conn.executescript(f.read())
  35             conn.execute(f'PRAGMA user_version = {EXPECTED_DB_VERSION}')
  36         return cls(path)
  37
  38     @classmethod
  39     def migrate(cls, path: str) -> DatabaseFile:
  40         """Apply migrations from_version to EXPECTED_DB_VERSION."""
  41         migrations = cls._available_migrations()
  42         from_version = cls._get_version_of_db(path)
  43         migrations_todo = migrations[from_version+1:]
  44         for j, filename in enumerate(migrations_todo):
  45             with sql_connect(path) as conn:
  46                 with open(f'{MIGRATIONS_DIR}/{filename}', 'r',
  47                           encoding='utf-8') as f:
  48                     conn.executescript(f.read())
  49             user_version = from_version + j + 1
  50             with sql_connect(path) as conn:
  51                 conn.execute(f'PRAGMA user_version = {user_version}')
  52         return cls(path)
  53
  54     def _check(self) -> None:
  55         """Check file exists, and is of proper DB version and schema."""
  56         if not isfile(self.path):
  57             raise NotFoundException
  58         if self._user_version != EXPECTED_DB_VERSION:
  59             raise UnmigratedDbException()
  60         self._validate_schema()
  61
  62     @staticmethod
  63     def _available_migrations() -> list[str]:
  64         """Validate migrations directory and return sorted entries."""
  65         msg_too_big = 'Migration directory points beyond expected DB version.'
  66         msg_bad_entry = 'Migration directory contains unexpected entry: '
  67         msg_missing = 'Migration directory misses migration of number: '
  68         migrations = {}
  69         for entry in listdir(MIGRATIONS_DIR):
  70             if entry == FILENAME_DB_SCHEMA:
  71                 continue
  72             toks = entry.split('_', 1)
  73             if len(toks) < 2:
  74                 raise HandledException(msg_bad_entry + entry)
  75             try:
  76                 i = int(toks[0])
  77             except ValueError as e:
  78                 raise HandledException(msg_bad_entry + entry) from e
  79             if i > EXPECTED_DB_VERSION:
  80                 raise HandledException(msg_too_big)
  81             migrations[i] = toks[1]
  82         migrations_list = []
  83         for i in range(EXPECTED_DB_VERSION + 1):
  84             if i not in migrations:
  85                 raise HandledException(msg_missing + str(i))
  86             migrations_list += [f'{i}_{migrations[i]}']
  87         return migrations_list
  88
  89     @staticmethod
  90     def _get_version_of_db(path: str) -> int:
  91         """Get DB user_version, fail if outside expected range."""
  92         sql_for_db_version = 'PRAGMA user_version'
  93         with sql_connect(path) as conn:
  94             db_version = list(conn.execute(sql_for_db_version))[0][0]
  95         if db_version > EXPECTED_DB_VERSION:
  96             msg = f'Wrong DB version, expected '\
  97                     f'{EXPECTED_DB_VERSION}, got unknown {db_version}.'
  98             raise HandledException(msg)
  99         assert isinstance(db_version, int)
 100         return db_version
 101
 102     @property
 103     def _user_version(self) -> int:
 104         """Get DB user_version."""
 105         return self._get_version_of_db(self.path)
 106
 107     def _validate_schema(self) -> None:
 108         """Compare found schema with what's stored at PATH_DB_SCHEMA."""
 109
 110         def reformat_rows(rows: list[str]) -> list[str]:
 111             new_rows = []
 112             for row in rows:
 113                 new_row = []
 114                 for subrow in row.split('\n'):
 115                     subrow = subrow.rstrip()
 116                     in_parentheses = 0
 117                     split_at = []
 118                     for i, c in enumerate(subrow):
 119                         if '(' == c:
 120                             in_parentheses += 1
 121                         elif ')' == c:
 122                             in_parentheses -= 1
 123                         elif ',' == c and 0 == in_parentheses:
 124                             split_at += [i + 1]
 125                     prev_split = 0
 126                     for i in split_at:
 127                         segment = subrow[prev_split:i].strip()
 128                         if len(segment) > 0:
 129                             new_row += [f'    {segment}']
 130                         prev_split = i
 131                     segment = subrow[prev_split:].strip()
 132                     if len(segment) > 0:
 133                         new_row += [f'    {segment}']
 134                 new_row[0] = new_row[0].lstrip()
 135                 new_row[-1] = new_row[-1].lstrip()
 136                 if new_row[-1] != ')' and new_row[-3][-1] != ',':
 137                     new_row[-3] = new_row[-3] + ','
 138                     new_row[-2:] = ['    ' + new_row[-1][:-1]] + [')']
 139                 new_rows += ['\n'.join(new_row)]
 140             return new_rows
 141
 142         sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
 143         msg_err = 'Database has wrong tables schema. Diff:\n'
 144         with sql_connect(self.path) as conn:
 145             schema_rows = [r[0] for r in conn.execute(sql_for_schema) if r[0]]
 146         schema_rows = reformat_rows(schema_rows)
 147         retrieved_schema = ';\n'.join(schema_rows) + ';'
 148         with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
 149             stored_schema = f.read().rstrip()
 150         if stored_schema != retrieved_schema:
 151             diff_msg = Differ().compare(retrieved_schema.splitlines(),
 152                                         stored_schema.splitlines())
 153             raise HandledException(msg_err + '\n'.join(diff_msg))
 154
 155
 156 class DatabaseConnection:
 157     """A single connection to the database."""
 158
 159     def __init__(self, db_file: DatabaseFile) -> None:
 160         self.conn = sql_connect(db_file.path)
 161
 162     def commit(self) -> None:
 163         """Commit SQL transaction."""
 164         self.conn.commit()
 165
 166     def exec(self, code: str, inputs: tuple[Any, ...] = tuple()) -> Cursor:
 167         """Add commands to SQL transaction."""
 168         return self.conn.execute(code, inputs)
 169
 170     def exec_on_vals(self, code: str, inputs: tuple[Any, ...]) -> Cursor:
 171         """Wrapper around .exec appending adequate " (?, …)" to code."""
 172         q_marks_from_values = '(' + ','.join(['?'] * len(inputs)) + ')'
 173         return self.exec(f'{code} {q_marks_from_values}', inputs)
 174
 175     def close(self) -> None:
 176         """Close DB connection."""
 177         self.conn.close()
 178
 179     def rewrite_relations(self, table_name: str, key: str, target: int | str,
 180                           rows: list[list[Any]], key_index: int = 0) -> None:
 181         # pylint: disable=too-many-arguments
 182         """Rewrite relations in table_name to target, with rows values.
 183
 184         Note that single rows are expected without the column and value
 185         identified by key and target, which are inserted inside the function
 186         at key_index.
 187         """
 188         self.delete_where(table_name, key, target)
 189         for row in rows:
 190             values = tuple(row[:key_index] + [target] + row[key_index:])
 191             self.exec_on_vals(f'INSERT INTO {table_name} VALUES', values)
 192
 193     def row_where(self, table_name: str, key: str,
 194                   target: int | str) -> list[Row]:
 195         """Return list of Rows at table where key == target."""
 196         return list(self.exec(f'SELECT * FROM {table_name} WHERE {key} = ?',
 197                               (target,)))
 198
 199     # def column_where_pattern(self,
 200     #                          table_name: str,
 201     #                          column: str,
 202     #                          pattern: str,
 203     #                          keys: list[str]) -> list[Any]:
 204     #     """Return column of rows where one of keys matches pattern."""
 205     #     targets = tuple([f'%{pattern}%'] * len(keys))
 206     #     haystack = ' OR '.join([f'{k} LIKE ?' for k in keys])
 207     #     sql = f'SELECT {column} FROM {table_name} WHERE {haystack}'
 208     #     return [row[0] for row in self.exec(sql, targets)]
 209
 210     def column_where(self, table_name: str, column: str, key: str,
 211                      target: int | str) -> list[Any]:
 212         """Return column of table where key == target."""
 213         return [row[0] for row in
 214                 self.exec(f'SELECT {column} FROM {table_name} '
 215                           f'WHERE {key} = ?', (target,))]
 216
 217     def column_all(self, table_name: str, column: str) -> list[Any]:
 218         """Return complete column of table."""
 219         return [row[0] for row in
 220                 self.exec(f'SELECT {column} FROM {table_name}')]
 221
 222     def delete_where(self, table_name: str, key: str,
 223                      target: int | str) -> None:
 224         """Delete from table where key == target."""
 225         self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
 226
 227
 228 BaseModelId = TypeVar('BaseModelId', int, str)
 229 BaseModelInstance = TypeVar('BaseModelInstance', bound='BaseModel[Any]')
 230
 231
 232 class BaseModel(Generic[BaseModelId]):
 233     """Template for most of the models we use/derive from the DB."""
 234     table_name = ''
 235     to_save: list[str] = []
 236     to_save_versioned: list[str] = []
 237     to_save_relations: list[tuple[str, str, str, int]] = []
 238     id_: None | BaseModelId
 239     cache_: dict[BaseModelId, Self]
 240     to_search: list[str] = []
 241     _exists = True
 242
 243     def __init__(self, id_: BaseModelId | None) -> None:
 244         if isinstance(id_, int) and id_ < 1:
 245             msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
 246             raise HandledException(msg)
 247         if isinstance(id_, str) and "" == id_:
 248             msg = f'illegal {self.__class__.__name__} ID, must be non-empty'
 249             raise HandledException(msg)
 250         self.id_ = id_
 251
 252     def __hash__(self) -> int:
 253         hashable = [self.id_] + [getattr(self, name) for name in self.to_save]
 254         for definition in self.to_save_relations:
 255             attr = getattr(self, definition[2])
 256             hashable += [tuple(rel.id_ for rel in attr)]
 257         for name in self.to_save_versioned:
 258             hashable += [hash(getattr(self, name))]
 259         return hash(tuple(hashable))
 260
 261     def __eq__(self, other: object) -> bool:
 262         if not isinstance(other, self.__class__):
 263             return False
 264         return hash(self) == hash(other)
 265
 266     def __lt__(self, other: Any) -> bool:
 267         if not isinstance(other, self.__class__):
 268             msg = 'cannot compare to object of different class'
 269             raise HandledException(msg)
 270         assert isinstance(self.id_, int)
 271         assert isinstance(other.id_, int)
 272         return self.id_ < other.id_
 273
 274     # cache management
 275     # (we primarily use the cache to ensure we work on the same object in
 276     # memory no matter where and how we retrieve it, e.g. we don't want
 277     # .by_id() calls to create a new object each time, but rather a pointer
 278     # to the one already instantiated)
 279
 280     def __getattribute__(self, name: str) -> Any:
 281         """Ensure fail if ._disappear() was called, except to check ._exists"""
 282         if name != '_exists' and not super().__getattribute__('_exists'):
 283             raise HandledException('Object does not exist.')
 284         return super().__getattribute__(name)
 285
 286     def _disappear(self) -> None:
 287         """Invalidate object, make future use raise exceptions."""
 288         assert self.id_ is not None
 289         if self._get_cached(self.id_):
 290             self._uncache()
 291         to_kill = list(self.__dict__.keys())
 292         for attr in to_kill:
 293             delattr(self, attr)
 294         self._exists = False
 295
 296     @classmethod
 297     def empty_cache(cls) -> None:
 298         """Empty class's cache."""
 299         cls.cache_ = {}
 300
 301     @classmethod
 302     def get_cache(cls: type[BaseModelInstance]) -> dict[Any, BaseModel[Any]]:
 303         """Get cache dictionary, create it if not yet existing."""
 304         if not hasattr(cls, 'cache_'):
 305             d: dict[Any, BaseModel[Any]] = {}
 306             cls.cache_ = d
 307         return cls.cache_
 308
 309     @classmethod
 310     def _get_cached(cls: type[BaseModelInstance],
 311                     id_: BaseModelId) -> BaseModelInstance | None:
 312         """Get object of id_ from class's cache, or None if not found."""
 313         # pylint: disable=consider-iterating-dictionary
 314         cache = cls.get_cache()
 315         if id_ in cache.keys():
 316             obj = cache[id_]
 317             assert isinstance(obj, cls)
 318             return obj
 319         return None
 320
 321     def _cache(self) -> None:
 322         """Update object in class's cache.
 323
 324         Also calls ._disappear if cache holds older reference to object of same
 325         ID, but different memory address, to avoid doing anything with
 326         dangling leftovers.
 327         """
 328         if self.id_ is None:
 329             raise HandledException('Cannot cache object without ID.')
 330         cache = self.get_cache()
 331         old_cached = self._get_cached(self.id_)
 332         if old_cached and id(old_cached) != id(self):
 333             # pylint: disable=protected-access
 334             # (cause we remain within the class)
 335             old_cached._disappear()
 336         cache[self.id_] = self
 337
 338     def _uncache(self) -> None:
 339         """Remove self from cache."""
 340         if self.id_ is None:
 341             raise HandledException('Cannot un-cache object without ID.')
 342         cache = self.get_cache()
 343         del cache[self.id_]
 344
 345     # object retrieval and generation
 346
 347     @classmethod
 348     def from_table_row(cls: type[BaseModelInstance],
 349                        # pylint: disable=unused-argument
 350                        db_conn: DatabaseConnection,
 351                        row: Row | list[Any]) -> BaseModelInstance:
 352         """Make from DB row, update DB cache with it."""
 353         obj = cls(*row)
 354         obj._cache()
 355         return obj
 356
 357     @classmethod
 358     def by_id(cls, db_conn: DatabaseConnection,
 359               id_: BaseModelId | None,
 360               # pylint: disable=unused-argument
 361               create: bool = False) -> Self:
 362         """Retrieve by id_, on failure throw NotFoundException.
 363
 364         First try to get from cls.cache_, only then check DB; if found,
 365         put into cache.
 366
 367         If create=True, make anew (but do not cache yet).
 368         """
 369         obj = None
 370         if id_ is not None:
 371             obj = cls._get_cached(id_)
 372             if not obj:
 373                 for row in db_conn.row_where(cls.table_name, 'id', id_):
 374                     obj = cls.from_table_row(db_conn, row)
 375                     break
 376         if obj:
 377             return obj
 378         if create:
 379             obj = cls(id_)
 380             return obj
 381         raise NotFoundException(f'found no object of ID {id_}')
 382
 383     @classmethod
 384     def all(cls: type[BaseModelInstance],
 385             db_conn: DatabaseConnection) -> list[BaseModelInstance]:
 386         """Collect all objects of class into list.
 387
 388         Note that this primarily returns the contents of the cache, and only
 389         _expands_ that by additional findings in the DB. This assumes the
 390         cache is always instantly cleaned of any items that would be removed
 391         from the DB.
 392         """
 393         items: dict[BaseModelId, BaseModelInstance] = {}
 394         for k, v in cls.get_cache().items():
 395             assert isinstance(v, cls)
 396             items[k] = v
 397         already_recorded = items.keys()
 398         for id_ in db_conn.column_all(cls.table_name, 'id'):
 399             if id_ not in already_recorded:
 400                 item = cls.by_id(db_conn, id_)
 401                 assert item.id_ is not None
 402                 items[item.id_] = item
 403         return list(items.values())
 404
 405     @classmethod
 406     def by_date_range_with_limits(cls: type[BaseModelInstance],
 407                                   db_conn: DatabaseConnection,
 408                                   date_range: tuple[str, str],
 409                                   date_col: str = 'day'
 410                                   ) -> tuple[list[BaseModelInstance], str,
 411                                              str]:
 412         """Return list of items in database within (open) date_range interval.
 413
 414         If no range values provided, defaults them to 'yesterday' and
 415         'tomorrow'. Knows to properly interpret these and 'today' as value.
 416         """
 417         start_str = date_range[0] if date_range[0] else 'yesterday'
 418         end_str = date_range[1] if date_range[1] else 'tomorrow'
 419         start_date = valid_date(start_str)
 420         end_date = valid_date(end_str)
 421         items = []
 422         sql = f'SELECT id FROM {cls.table_name} '
 423         sql += f'WHERE {date_col} >= ? AND {date_col} <= ?'
 424         for row in db_conn.exec(sql, (start_date, end_date)):
 425             items += [cls.by_id(db_conn, row[0])]
 426         return items, start_date, end_date
 427
 428     @classmethod
 429     def matching(cls: type[BaseModelInstance], db_conn: DatabaseConnection,
 430                  pattern: str) -> list[BaseModelInstance]:
 431         """Return all objects whose .to_search match pattern."""
 432         items = cls.all(db_conn)
 433         if pattern:
 434             filtered = []
 435             for item in items:
 436                 for attr_name in cls.to_search:
 437                     toks = attr_name.split('.')
 438                     parent = item
 439                     for tok in toks:
 440                         attr = getattr(parent, tok)
 441                         parent = attr
 442                     if pattern in attr:
 443                         filtered += [item]
 444                         break
 445             return filtered
 446         return items
 447
 448     # database writing
 449
 450     def save(self, db_conn: DatabaseConnection) -> None:
 451         """Write self to DB and cache and ensure .id_.
 452
 453         Write both to DB, and to cache. To DB, write .id_ and attributes
 454         listed in cls.to_save[_versioned|_relations].
 455
 456         Ensure self.id_ by setting it to what the DB command returns as the
 457         last saved row's ID (cursor.lastrowid), EXCEPT if self.id_ already
 458         exists as a 'str', which implies we do our own ID creation (so far
 459         only the case with the Day class, where it's to be a date string.
 460         """
 461         values = tuple([self.id_] + [getattr(self, key)
 462                                      for key in self.to_save])
 463         table_name = self.table_name
 464         cursor = db_conn.exec_on_vals(f'REPLACE INTO {table_name} VALUES',
 465                                       values)
 466         if not isinstance(self.id_, str):
 467             self.id_ = cursor.lastrowid  # type: ignore[assignment]
 468         self._cache()
 469         for attr_name in self.to_save_versioned:
 470             getattr(self, attr_name).save(db_conn)
 471         for table, column, attr_name, key_index in self.to_save_relations:
 472             assert isinstance(self.id_, (int, str))
 473             db_conn.rewrite_relations(table, column, self.id_,
 474                                       [[i.id_] for i
 475                                        in getattr(self, attr_name)], key_index)
 476
 477     def remove(self, db_conn: DatabaseConnection) -> None:
 478         """Remove from DB and cache, including dependencies."""
 479         if self.id_ is None or self._get_cached(self.id_) is None:
 480             raise HandledException('cannot remove unsaved item')
 481         for attr_name in self.to_save_versioned:
 482             getattr(self, attr_name).remove(db_conn)
 483         for table, column, attr_name, _ in self.to_save_relations:
 484             db_conn.delete_where(table, column, self.id_)
 485         self._uncache()
 486         db_conn.delete_where(self.table_name, 'id', self.id_)
 487         self._disappear()