1 """Database management."""
2 from __future__ import annotations
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, Callable
8 from plomtask.exceptions import HandledException, NotFoundException
9 from plomtask.dating import valid_date
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}'
17 class UnmigratedDbException(HandledException):
18 """To identify case of unmigrated DB file."""
22 """Represents the sqlite3 database's file."""
23 # pylint: disable=too-few-public-methods
25 def __init__(self, path: str) -> None:
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}')
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}')
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()
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: '
69 for entry in listdir(MIGRATIONS_DIR):
70 if entry == FILENAME_DB_SCHEMA:
72 toks = entry.split('_', 1)
74 raise HandledException(msg_bad_entry + entry)
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]
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
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)
103 def _user_version(self) -> int:
104 """Get DB user_version."""
105 return self._get_version_of_db(self.path)
107 def _validate_schema(self) -> None:
108 """Compare found schema with what's stored at PATH_DB_SCHEMA."""
110 def reformat_rows(rows: list[str]) -> list[str]:
114 for subrow in row.split('\n'):
115 subrow = subrow.rstrip()
118 for i, c in enumerate(subrow):
123 elif ',' == c and 0 == in_parentheses:
127 segment = subrow[prev_split:i].strip()
129 new_row += [f' {segment}']
131 segment = subrow[prev_split:].strip()
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)]
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))
156 class DatabaseConnection:
157 """A single connection to the database."""
159 def __init__(self, db_file: DatabaseFile) -> None:
160 self.conn = sql_connect(db_file.path)
162 def commit(self) -> None:
163 """Commit SQL transaction."""
166 def exec(self, code: str, inputs: tuple[Any, ...] = tuple()) -> Cursor:
167 """Add commands to SQL transaction."""
168 return self.conn.execute(code, inputs)
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)
175 def close(self) -> None:
176 """Close DB connection."""
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.
184 Note that single rows are expected without the column and value
185 identified by key and target, which are inserted inside the function
188 self.delete_where(table_name, key, target)
190 values = tuple(row[:key_index] + [target] + row[key_index:])
191 self.exec_on_vals(f'INSERT INTO {table_name} VALUES', values)
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} = ?',
199 # def column_where_pattern(self,
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)]
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,))]
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}')]
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,))
228 BaseModelId = TypeVar('BaseModelId', int, str)
229 BaseModelInstance = TypeVar('BaseModelInstance', bound='BaseModel[Any]')
232 class BaseModel(Generic[BaseModelId]):
233 """Template for most of the models we use/derive from the DB."""
235 to_save_simples: list[str] = []
236 to_save_relations: list[tuple[str, str, str, int]] = []
237 versioned_defaults: dict[str, str | float] = {}
238 add_to_dict: list[str] = []
239 id_: None | BaseModelId
240 cache_: dict[BaseModelId, Self]
241 to_search: list[str] = []
242 can_create_by_id = False
244 sorters: dict[str, Callable[..., Any]] = {}
246 def __init__(self, id_: BaseModelId | None) -> None:
247 if isinstance(id_, int) and id_ < 1:
248 msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
249 raise HandledException(msg)
250 if isinstance(id_, str) and "" == id_:
251 msg = f'illegal {self.__class__.__name__} ID, must be non-empty'
252 raise HandledException(msg)
255 def __hash__(self) -> int:
256 hashable = [self.id_] + [getattr(self, name)
257 for name in self.to_save_simples]
258 for definition in self.to_save_relations:
259 attr = getattr(self, definition[2])
260 hashable += [tuple(rel.id_ for rel in attr)]
261 for name in self.to_save_versioned():
262 hashable += [hash(getattr(self, name))]
263 return hash(tuple(hashable))
265 def __eq__(self, other: object) -> bool:
266 if not isinstance(other, self.__class__):
268 return hash(self) == hash(other)
270 def __lt__(self, other: Any) -> bool:
271 if not isinstance(other, self.__class__):
272 msg = 'cannot compare to object of different class'
273 raise HandledException(msg)
274 assert isinstance(self.id_, int)
275 assert isinstance(other.id_, int)
276 return self.id_ < other.id_
279 def to_save_versioned(cls) -> list[str]:
280 """Return keys of cls.versioned_defaults assuming we wanna save 'em."""
281 return list(cls.versioned_defaults.keys())
284 def as_dict(self) -> dict[str, object]:
285 """Return self as (json.dumps-compatible) dict."""
286 library: dict[str, dict[str | int, object]] = {}
287 d: dict[str, object] = {'id': self.id_, '_library': library}
288 for to_save in self.to_save_simples:
289 attr = getattr(self, to_save)
290 if hasattr(attr, 'as_dict_into_reference'):
291 d[to_save] = attr.as_dict_into_reference(library)
294 if len(self.to_save_versioned()) > 0:
296 for k in self.to_save_versioned():
297 attr = getattr(self, k)
298 assert isinstance(d['_versioned'], dict)
299 d['_versioned'][k] = attr.history
300 for r in self.to_save_relations:
302 l: list[int | str] = []
303 for rel in getattr(self, attr_name):
304 l += [rel.as_dict_into_reference(library)]
306 for k in self.add_to_dict:
307 d[k] = [x.as_dict_into_reference(library)
308 for x in getattr(self, k)]
311 def as_dict_into_reference(self,
312 library: dict[str, dict[str | int, object]]
314 """Return self.id_ while writing .as_dict into library."""
315 def into_library(library: dict[str, dict[str | int, object]],
320 if cls_name not in library:
321 library[cls_name] = {}
322 if id_ in library[cls_name]:
323 if library[cls_name][id_] != d:
324 msg = 'Unexpected inequality of entries for ' +\
325 f'_library at: {cls_name}/{id_}'
326 raise HandledException(msg)
328 library[cls_name][id_] = d
329 as_dict = self.as_dict
330 assert isinstance(as_dict['_library'], dict)
331 for cls_name, dict_of_objs in as_dict['_library'].items():
332 for id_, obj in dict_of_objs.items():
333 into_library(library, cls_name, id_, obj)
334 del as_dict['_library']
335 assert self.id_ is not None
336 into_library(library, self.__class__.__name__, self.id_, as_dict)
337 assert isinstance(as_dict['id'], (int, str))
341 def name_lowercase(cls) -> str:
342 """Convenience method to return cls' name in lowercase."""
343 return cls.__name__.lower()
346 def sort_by(cls, seq: list[Any], sort_key: str, default: str = 'title'
348 """Sort cls list by cls.sorters[sort_key] (reverse if '-'-prefixed).
350 Before cls.sorters[sort_key] is applied, seq is sorted by .id_, to
351 ensure predictability where parts of seq are of same sort value.
354 if len(sort_key) > 1 and '-' == sort_key[0]:
355 sort_key = sort_key[1:]
357 if sort_key not in cls.sorters:
359 seq.sort(key=lambda x: x.id_, reverse=reverse)
360 sorter: Callable[..., Any] = cls.sorters[sort_key]
361 seq.sort(key=sorter, reverse=reverse)
363 sort_key = f'-{sort_key}'
367 # (we primarily use the cache to ensure we work on the same object in
368 # memory no matter where and how we retrieve it, e.g. we don't want
369 # .by_id() calls to create a new object each time, but rather a pointer
370 # to the one already instantiated)
372 def __getattribute__(self, name: str) -> Any:
373 """Ensure fail if ._disappear() was called, except to check ._exists"""
374 if name != '_exists' and not super().__getattribute__('_exists'):
375 raise HandledException('Object does not exist.')
376 return super().__getattribute__(name)
378 def _disappear(self) -> None:
379 """Invalidate object, make future use raise exceptions."""
380 assert self.id_ is not None
381 if self._get_cached(self.id_):
383 to_kill = list(self.__dict__.keys())
389 def empty_cache(cls) -> None:
390 """Empty class's cache, and disappear all former inhabitants."""
391 # pylint: disable=protected-access
392 # (cause we remain within the class)
393 if hasattr(cls, 'cache_'):
394 to_disappear = list(cls.cache_.values())
395 for item in to_disappear:
400 def get_cache(cls: type[BaseModelInstance]) -> dict[Any, BaseModel[Any]]:
401 """Get cache dictionary, create it if not yet existing."""
402 if not hasattr(cls, 'cache_'):
403 d: dict[Any, BaseModel[Any]] = {}
408 def _get_cached(cls: type[BaseModelInstance],
409 id_: BaseModelId) -> BaseModelInstance | None:
410 """Get object of id_ from class's cache, or None if not found."""
411 cache = cls.get_cache()
414 assert isinstance(obj, cls)
418 def cache(self) -> None:
419 """Update object in class's cache.
421 Also calls ._disappear if cache holds older reference to object of same
422 ID, but different memory address, to avoid doing anything with
426 raise HandledException('Cannot cache object without ID.')
427 cache = self.get_cache()
428 old_cached = self._get_cached(self.id_)
429 if old_cached and id(old_cached) != id(self):
430 # pylint: disable=protected-access
431 # (cause we remain within the class)
432 old_cached._disappear()
433 cache[self.id_] = self
435 def _uncache(self) -> None:
436 """Remove self from cache."""
438 raise HandledException('Cannot un-cache object without ID.')
439 cache = self.get_cache()
442 # object retrieval and generation
445 def from_table_row(cls: type[BaseModelInstance],
446 # pylint: disable=unused-argument
447 db_conn: DatabaseConnection,
448 row: Row | list[Any]) -> BaseModelInstance:
449 """Make from DB row (sans relations), update DB cache with it."""
451 assert obj.id_ is not None
452 for attr_name in cls.to_save_versioned():
453 attr = getattr(obj, attr_name)
454 table_name = attr.table_name
455 for row_ in db_conn.row_where(table_name, 'parent', obj.id_):
456 attr.history_from_row(row_)
461 def by_id(cls, db_conn: DatabaseConnection, id_: BaseModelId) -> Self:
462 """Retrieve by id_, on failure throw NotFoundException.
464 First try to get from cls.cache_, only then check DB; if found,
469 obj = cls._get_cached(id_)
471 for row in db_conn.row_where(cls.table_name, 'id', id_):
472 obj = cls.from_table_row(db_conn, row)
476 raise NotFoundException(f'found no object of ID {id_}')
479 def by_id_or_create(cls, db_conn: DatabaseConnection,
480 id_: BaseModelId | None
482 """Wrapper around .by_id, creating (not caching/saving) if not find."""
483 if not cls.can_create_by_id:
484 raise HandledException('Class cannot .by_id_or_create.')
488 return cls.by_id(db_conn, id_)
489 except NotFoundException:
493 def all(cls: type[BaseModelInstance],
494 db_conn: DatabaseConnection) -> list[BaseModelInstance]:
495 """Collect all objects of class into list.
497 Note that this primarily returns the contents of the cache, and only
498 _expands_ that by additional findings in the DB. This assumes the
499 cache is always instantly cleaned of any items that would be removed
502 items: dict[BaseModelId, BaseModelInstance] = {}
503 for k, v in cls.get_cache().items():
504 assert isinstance(v, cls)
506 already_recorded = items.keys()
507 for id_ in db_conn.column_all(cls.table_name, 'id'):
508 if id_ not in already_recorded:
509 item = cls.by_id(db_conn, id_)
510 assert item.id_ is not None
511 items[item.id_] = item
512 return list(items.values())
515 def by_date_range_with_limits(cls: type[BaseModelInstance],
516 db_conn: DatabaseConnection,
517 date_range: tuple[str, str],
518 date_col: str = 'day'
519 ) -> tuple[list[BaseModelInstance], str,
521 """Return list of items in DB within (closed) date_range interval.
523 If no range values provided, defaults them to 'yesterday' and
524 'tomorrow'. Knows to properly interpret these and 'today' as value.
526 start_str = date_range[0] if date_range[0] else 'yesterday'
527 end_str = date_range[1] if date_range[1] else 'tomorrow'
528 start_date = valid_date(start_str)
529 end_date = valid_date(end_str)
531 sql = f'SELECT id FROM {cls.table_name} '
532 sql += f'WHERE {date_col} >= ? AND {date_col} <= ?'
533 for row in db_conn.exec(sql, (start_date, end_date)):
534 items += [cls.by_id(db_conn, row[0])]
535 return items, start_date, end_date
538 def matching(cls: type[BaseModelInstance], db_conn: DatabaseConnection,
539 pattern: str) -> list[BaseModelInstance]:
540 """Return all objects whose .to_search match pattern."""
541 items = cls.all(db_conn)
545 for attr_name in cls.to_search:
546 toks = attr_name.split('.')
549 attr = getattr(parent, tok)
559 def save(self, db_conn: DatabaseConnection) -> None:
560 """Write self to DB and cache and ensure .id_.
562 Write both to DB, and to cache. To DB, write .id_ and attributes
563 listed in cls.to_save_[simples|versioned|_relations].
565 Ensure self.id_ by setting it to what the DB command returns as the
566 last saved row's ID (cursor.lastrowid), EXCEPT if self.id_ already
567 exists as a 'str', which implies we do our own ID creation (so far
568 only the case with the Day class, where it's to be a date string.
570 values = tuple([self.id_] + [getattr(self, key)
571 for key in self.to_save_simples])
572 table_name = self.table_name
573 cursor = db_conn.exec_on_vals(f'REPLACE INTO {table_name} VALUES',
575 if not isinstance(self.id_, str):
576 self.id_ = cursor.lastrowid # type: ignore[assignment]
578 for attr_name in self.to_save_versioned():
579 getattr(self, attr_name).save(db_conn)
580 for table, column, attr_name, key_index in self.to_save_relations:
581 assert isinstance(self.id_, (int, str))
582 db_conn.rewrite_relations(table, column, self.id_,
584 in getattr(self, attr_name)], key_index)
586 def remove(self, db_conn: DatabaseConnection) -> None:
587 """Remove from DB and cache, including dependencies."""
588 if self.id_ is None or self._get_cached(self.id_) is None:
589 raise HandledException('cannot remove unsaved item')
590 for attr_name in self.to_save_versioned():
591 getattr(self, attr_name).remove(db_conn)
592 for table, column, attr_name, _ in self.to_save_relations:
593 db_conn.delete_where(table, column, self.id_)
595 db_conn.delete_where(self.table_name, 'id', self.id_)