Coverage for /var/devmt/py/dbilib_0.0.1.dev1/dbilib/_dbi_sqlite.py: 100%
17 statements
« prev ^ index » next coverage.py v7.6.1, created at 2024-08-07 23:49 +0100
« prev ^ index » next coverage.py v7.6.1, created at 2024-08-07 23:49 +0100
1#!/usr/bin/env python3
2# -*- coding: utf-8 -*-
3"""
4:Purpose: This module contains the library's *SQLite* database methods
5 and attribute accessors; which are a specialised version of
6 the :class:`_dbi_base._DBIBase` class methods.
8:Platform: Linux/Windows | Python 3.10+
9:Developer: J Berendt
10:Email: support@s3dev.uk
12:Comments: n/a
14:Example:
16 For class-specific usage examples, please refer to the docstring
17 for the following classes:
19 - :class:`_DBISQLite`
21"""
22# Silence the spurious IDE-based error.
23# pylint: disable=import-error
25from utils4 import utils
26from utils4.user_interface import ui
27# locals
28from _dbi_base import _DBIBase
31class _DBISQLite(_DBIBase):
32 """This *private* class holds the methods and properties which are
33 used for accessing SQLite databases.
35 Note:
36 This class is *not* designed to be interacted with directly.
38 Rather, please use the :class:`database.DBInterface` class
39 instead, as the proper interface class has an automatic switch
40 for database interfaces, based on the ``sqlalchemy.Engine``
41 object which is created from the connection string.
43 Args:
44 connstr (str): The database-specific SQLAlchemy connection
45 string.
47 :Example Use:
49 This low-level generalised class is designed to be inherited by
50 the calling/wrapping class as::
52 >>> from dblib.database import DBInterface
54 class MyDB(DBInterface):
56 def __init__(self, connstr: str):
57 super().__init__(connstr=('sqlite:////path/to/database.db'))
59 """
61 def __init__(self, connstr: str):
62 """SQLite database interface initialiser."""
63 super().__init__(connstr=connstr)
64 self._verify_db_exists()
66 def table_exists(self, table_name: str, verbose: bool=False) -> bool:
67 """Using the ``engine`` object, test if the given table exists.
69 Args:
70 table_name (str): Name of the table to test.
71 verbose (bool, optional): Print a message if the table does
72 not exist. Defaults to False.
74 Returns:
75 bool: True if the given table exists, otherwise False.
77 """
78 params = {'table_name': table_name}
79 stmt = ('select count(*) from sqlite_master '
80 'where type = \'table\' '
81 'and name = :table_name')
82 exists = bool(self.execute_query(stmt, params=params, raw=True)[0][0])
83 if (not exists) & verbose:
84 msg = f'Table does not exist: {self._engine.url.database}.{table_name}'
85 ui.print_warning(text=msg)
86 return exists
88 def _verify_db_exists(self):
89 """Verify the database file exists.
91 Raises:
92 FileNotFoundError: Raised if the database file passed via the
93 connection string does not exist.
95 """
96 utils.fileexists(filepath=self.engine.url.database, error='raise')