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 if len(sort_key) > 1 and '-' == sort_key[0]:
351 sort_key = sort_key[1:]
353 if sort_key not in cls.sorters:
355 sorter: Callable[..., Any] = cls.sorters[sort_key]
356 seq.sort(key=sorter, reverse=reverse)
358 sort_key = f'-{sort_key}'
362 # (we primarily use the cache to ensure we work on the same object in
363 # memory no matter where and how we retrieve it, e.g. we don't want
364 # .by_id() calls to create a new object each time, but rather a pointer
365 # to the one already instantiated)
367 def __getattribute__(self, name: str) -> Any:
368 """Ensure fail if ._disappear() was called, except to check ._exists"""
369 if name != '_exists' and not super().__getattribute__('_exists'):
370 raise HandledException('Object does not exist.')
371 return super().__getattribute__(name)
373 def _disappear(self) -> None:
374 """Invalidate object, make future use raise exceptions."""
375 assert self.id_ is not None
376 if self._get_cached(self.id_):
378 to_kill = list(self.__dict__.keys())
384 def empty_cache(cls) -> None:
385 """Empty class's cache, and disappear all former inhabitants."""
386 # pylint: disable=protected-access
387 # (cause we remain within the class)
388 if hasattr(cls, 'cache_'):
389 to_disappear = list(cls.cache_.values())
390 for item in to_disappear:
395 def get_cache(cls: type[BaseModelInstance]) -> dict[Any, BaseModel[Any]]:
396 """Get cache dictionary, create it if not yet existing."""
397 if not hasattr(cls, 'cache_'):
398 d: dict[Any, BaseModel[Any]] = {}
403 def _get_cached(cls: type[BaseModelInstance],
404 id_: BaseModelId) -> BaseModelInstance | None:
405 """Get object of id_ from class's cache, or None if not found."""
406 cache = cls.get_cache()
409 assert isinstance(obj, cls)
413 def cache(self) -> None:
414 """Update object in class's cache.
416 Also calls ._disappear if cache holds older reference to object of same
417 ID, but different memory address, to avoid doing anything with
421 raise HandledException('Cannot cache object without ID.')
422 cache = self.get_cache()
423 old_cached = self._get_cached(self.id_)
424 if old_cached and id(old_cached) != id(self):
425 # pylint: disable=protected-access
426 # (cause we remain within the class)
427 old_cached._disappear()
428 cache[self.id_] = self
430 def _uncache(self) -> None:
431 """Remove self from cache."""
433 raise HandledException('Cannot un-cache object without ID.')
434 cache = self.get_cache()
437 # object retrieval and generation
440 def from_table_row(cls: type[BaseModelInstance],
441 # pylint: disable=unused-argument
442 db_conn: DatabaseConnection,
443 row: Row | list[Any]) -> BaseModelInstance:
444 """Make from DB row (sans relations), update DB cache with it."""
446 assert obj.id_ is not None
447 for attr_name in cls.to_save_versioned():
448 attr = getattr(obj, attr_name)
449 table_name = attr.table_name
450 for row_ in db_conn.row_where(table_name, 'parent', obj.id_):
451 attr.history_from_row(row_)
456 def by_id(cls, db_conn: DatabaseConnection, id_: BaseModelId) -> Self:
457 """Retrieve by id_, on failure throw NotFoundException.
459 First try to get from cls.cache_, only then check DB; if found,
464 obj = cls._get_cached(id_)
466 for row in db_conn.row_where(cls.table_name, 'id', id_):
467 obj = cls.from_table_row(db_conn, row)
471 raise NotFoundException(f'found no object of ID {id_}')
474 def by_id_or_create(cls, db_conn: DatabaseConnection,
475 id_: BaseModelId | None
477 """Wrapper around .by_id, creating (not caching/saving) if not find."""
478 if not cls.can_create_by_id:
479 raise HandledException('Class cannot .by_id_or_create.')
483 return cls.by_id(db_conn, id_)
484 except NotFoundException:
488 def all(cls: type[BaseModelInstance],
489 db_conn: DatabaseConnection) -> list[BaseModelInstance]:
490 """Collect all objects of class into list.
492 Note that this primarily returns the contents of the cache, and only
493 _expands_ that by additional findings in the DB. This assumes the
494 cache is always instantly cleaned of any items that would be removed
497 items: dict[BaseModelId, BaseModelInstance] = {}
498 for k, v in cls.get_cache().items():
499 assert isinstance(v, cls)
501 already_recorded = items.keys()
502 for id_ in db_conn.column_all(cls.table_name, 'id'):
503 if id_ not in already_recorded:
504 item = cls.by_id(db_conn, id_)
505 assert item.id_ is not None
506 items[item.id_] = item
507 return list(items.values())
510 def by_date_range_with_limits(cls: type[BaseModelInstance],
511 db_conn: DatabaseConnection,
512 date_range: tuple[str, str],
513 date_col: str = 'day'
514 ) -> tuple[list[BaseModelInstance], str,
516 """Return list of items in database within (open) date_range interval.
518 If no range values provided, defaults them to 'yesterday' and
519 'tomorrow'. Knows to properly interpret these and 'today' as value.
521 start_str = date_range[0] if date_range[0] else 'yesterday'
522 end_str = date_range[1] if date_range[1] else 'tomorrow'
523 start_date = valid_date(start_str)
524 end_date = valid_date(end_str)
526 sql = f'SELECT id FROM {cls.table_name} '
527 sql += f'WHERE {date_col} >= ? AND {date_col} <= ?'
528 for row in db_conn.exec(sql, (start_date, end_date)):
529 items += [cls.by_id(db_conn, row[0])]
530 return items, start_date, end_date
533 def matching(cls: type[BaseModelInstance], db_conn: DatabaseConnection,
534 pattern: str) -> list[BaseModelInstance]:
535 """Return all objects whose .to_search match pattern."""
536 items = cls.all(db_conn)
540 for attr_name in cls.to_search:
541 toks = attr_name.split('.')
544 attr = getattr(parent, tok)
554 def save(self, db_conn: DatabaseConnection) -> None:
555 """Write self to DB and cache and ensure .id_.
557 Write both to DB, and to cache. To DB, write .id_ and attributes
558 listed in cls.to_save_[simples|versioned|_relations].
560 Ensure self.id_ by setting it to what the DB command returns as the
561 last saved row's ID (cursor.lastrowid), EXCEPT if self.id_ already
562 exists as a 'str', which implies we do our own ID creation (so far
563 only the case with the Day class, where it's to be a date string.
565 values = tuple([self.id_] + [getattr(self, key)
566 for key in self.to_save_simples])
567 table_name = self.table_name
568 cursor = db_conn.exec_on_vals(f'REPLACE INTO {table_name} VALUES',
570 if not isinstance(self.id_, str):
571 self.id_ = cursor.lastrowid # type: ignore[assignment]
573 for attr_name in self.to_save_versioned():
574 getattr(self, attr_name).save(db_conn)
575 for table, column, attr_name, key_index in self.to_save_relations:
576 assert isinstance(self.id_, (int, str))
577 db_conn.rewrite_relations(table, column, self.id_,
579 in getattr(self, attr_name)], key_index)
581 def remove(self, db_conn: DatabaseConnection) -> None:
582 """Remove from DB and cache, including dependencies."""
583 if self.id_ is None or self._get_cached(self.id_) is None:
584 raise HandledException('cannot remove unsaved item')
585 for attr_name in self.to_save_versioned():
586 getattr(self, attr_name).remove(db_conn)
587 for table, column, attr_name, _ in self.to_save_relations:
588 db_conn.delete_where(table, column, self.id_)
590 db_conn.delete_where(self.table_name, 'id', self.id_)