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
   5 from plomtask.misc import HandledException
   6
   7 PATH_DB_SCHEMA = 'scripts/init.sql'
   8
   9
  10 class DatabaseFile:  # pylint: disable=too-few-public-methods
  11     """Represents the sqlite3 database's file."""
  12
  13     def __init__(self, path):
  14         self.path = path
  15         self._check()
  16
  17     def remake(self):
  18         """Create tables in self.path file as per PATH_DB_SCHEMA sql file."""
  19         with sql_connect(self.path) as conn:
  20             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
  21                 conn.executescript(f.read())
  22         self._check()
  23
  24     def _check(self):
  25         """Check file exists and is of proper schema."""
  26         self.exists = isfile(self.path)
  27         if self.exists:
  28             self._validate_schema()
  29
  30     def _validate_schema(self):
  31         """Compare found schema with what's stored at PATH_DB_SCHEMA."""
  32         sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
  33         msg_err = 'Database has wrong tables schema. Diff:\n'
  34         with sql_connect(self.path) as conn:
  35             schema_rows = [r[0] for r in conn.execute(sql_for_schema) if r[0]]
  36             retrieved_schema = ';\n'.join(schema_rows) + ';'
  37             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
  38                 stored_schema = f.read().rstrip()
  39                 if stored_schema != retrieved_schema:
  40                     diff_msg = Differ().compare(retrieved_schema.splitlines(),
  41                                                 stored_schema.splitlines())
  42                     raise HandledException(msg_err + '\n'.join(diff_msg))
  43
  44
  45 class DatabaseConnection:
  46     """A single connection to the database."""
  47
  48     def __init__(self, db_file: DatabaseFile):
  49         self.file = db_file
  50         self.conn = sql_connect(self.file.path)
  51
  52     def commit(self):
  53         """Commit SQL transaction."""
  54         self.conn.commit()
  55
  56     def exec(self, code: str, inputs: tuple = ()):
  57         """Add commands to SQL transaction."""
  58         return self.conn.execute(code, inputs)
  59
  60     def close(self):
  61         """Close DB connection."""
  62         self.conn.close()