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

   1 """Database management."""
   2 from os.path import isfile
   3 from difflib import Differ
   4 from sqlite3 import connect as sql_connect, Cursor, Row
   5 from typing import Any, Dict
   6 from plomtask.exceptions import HandledException
   7
   8 PATH_DB_SCHEMA = 'scripts/init.sql'
   9
  10
  11 class DatabaseFile:  # pylint: disable=too-few-public-methods
  12     """Represents the sqlite3 database's file."""
  13
  14     def __init__(self, path: str) -> None:
  15         self.path = path
  16         self._check()
  17
  18     def remake(self) -> None:
  19         """Create tables in self.path file as per PATH_DB_SCHEMA sql file."""
  20         with sql_connect(self.path) as conn:
  21             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
  22                 conn.executescript(f.read())
  23         self._check()
  24
  25     def _check(self) -> None:
  26         """Check file exists, and is of proper schema."""
  27         self.exists = isfile(self.path)
  28         if self.exists:
  29             self._validate_schema()
  30
  31     def _validate_schema(self) -> None:
  32         """Compare found schema with what's stored at PATH_DB_SCHEMA."""
  33         sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
  34         msg_err = 'Database has wrong tables schema. Diff:\n'
  35         with sql_connect(self.path) as conn:
  36             schema_rows = [r[0] for r in conn.execute(sql_for_schema) if r[0]]
  37             retrieved_schema = ';\n'.join(schema_rows) + ';'
  38             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
  39                 stored_schema = f.read().rstrip()
  40                 if stored_schema != retrieved_schema:
  41                     diff_msg = Differ().compare(retrieved_schema.splitlines(),
  42                                                 stored_schema.splitlines())
  43                     raise HandledException(msg_err + '\n'.join(diff_msg))
  44
  45
  46 class DatabaseConnection:
  47     """A single connection to the database."""
  48
  49     def __init__(self, db_file: DatabaseFile) -> None:
  50         self.file = db_file
  51         self.conn = sql_connect(self.file.path)
  52         self.cached_todos: Dict[int, Any] = {}
  53         self.cached_days: Dict[str, Any] = {}
  54         self.cached_process_steps: Dict[int, Any] = {}
  55         self.cached_processes: Dict[int, Any] = {}
  56         self.cached_conditions: Dict[int, Any] = {}
  57
  58     def commit(self) -> None:
  59         """Commit SQL transaction."""
  60         self.conn.commit()
  61
  62     def exec(self, code: str, inputs: tuple[Any, ...] = tuple()) -> Cursor:
  63         """Add commands to SQL transaction."""
  64         return self.conn.execute(code, inputs)
  65
  66     def close(self) -> None:
  67         """Close DB connection."""
  68         self.conn.close()
  69
  70
  71 class BaseModel:
  72     """Template for most of the models we use/derive from the DB."""
  73     table_name = ''
  74     to_save: list[str] = []
  75     id_: None | int | str
  76     id_type: type[Any] = int
  77
  78     @classmethod
  79     def from_table_row(cls, db_conn: DatabaseConnection,
  80                        row: Row | list[Any]) -> Any:
  81         """Make from DB row, write to DB cache."""
  82         obj = cls(*row)
  83         assert isinstance(obj.id_, cls.id_type)
  84         cache = getattr(db_conn, f'cached_{cls.table_name}')
  85         cache[obj.id_] = obj
  86         return obj
  87
  88     @classmethod
  89     def _by_id(cls,
  90                db_conn: DatabaseConnection,
  91                id_: int | str) -> tuple[Any, bool]:
  92         """Return instance found by ID, or None, and if from cache or not."""
  93         from_cache = False
  94         obj = None
  95         cache = getattr(db_conn, f'cached_{cls.table_name}')
  96         if id_ in cache.keys():
  97             obj = cache[id_]
  98             from_cache = True
  99         else:
 100             for row in db_conn.exec(f'SELECT * FROM {cls.table_name} '
 101                                     'WHERE id = ?', (id_,)):
 102                 obj = cls.from_table_row(db_conn, row)
 103                 cache[id_] = obj
 104                 break
 105         return obj, from_cache
 106
 107     def set_int_id(self, id_: int | None) -> None:
 108         """Set id_ if >= 1 or None, else fail."""
 109         if (id_ is not None) and id_ < 1:
 110             msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
 111             raise HandledException(msg)
 112         self.id_ = id_
 113
 114     def save_core(self, db_conn: DatabaseConnection,
 115                   update_with_lastrowid: bool = True) -> None:
 116         """Write bare-bones self (sans connected items), ensuring self.id_."""
 117         q_marks = ','.join(['?'] * (len(self.to_save) + 1))
 118         values = tuple([self.id_] + [getattr(self, key)
 119                                      for key in self.to_save])
 120         table_name = self.table_name
 121         cursor = db_conn.exec(f'REPLACE INTO {table_name} VALUES ({q_marks})',
 122                               values)
 123         if update_with_lastrowid:
 124             self.id_ = cursor.lastrowid
 125         cache = getattr(db_conn, f'cached_{table_name}')
 126         cache[self.id_] = self