lib/tools/connector.py

   1 from pathlib import Path
   2 import psycopg2
   3 import configparser
   4
   5 class Singleton:
   6
   7     def __init__(self, cls):
   8         self._cls = cls
   9
  10     def Instance(self):
  11         try:
  12             return self._instance
  13         except AttributeError:
  14             self._instance = self._cls()
  15             return self._instance
  16
  17     def __call__(self):
  18         raise TypeError('Singletons must be accessed through `Instance()`.')
  19
  20     def __instancecheck__(self, inst):
  21         return isinstance(inst, self._cls)
  22
  23 @Singleton
  24 class PostgreSQLDBConnection(object):
  25     """Postgresql database connection"""
  26
  27     def __init__(self, connection_string = ''):
  28         if connection_string == '':
  29             # We're retrieving information related to the database in config.ini
  30             config = configparser.ConfigParser()
  31             config.read((Path.cwd() / 'config') / 'main.cfg')
  32
  33             host   = config['postgresql']['host']
  34             user   = config['postgresql']['user']
  35             port   = config['postgresql']['port']
  36             self.dbname = config['postgresql']['dbname']
  37
  38             self.connection_string = f"host={host} port={port} dbname={self.dbname} user={user}"
  39
  40         else:
  41             self.connection_string = connection_string
  42             self.dbname = ''
  43
  44
  45     def __enter__(self):
  46         self.connection = psycopg2.connect(self.connection_string)
  47         self.connection.autocommit = True
  48         self.cursor = self.connection.cursor()
  49         return self
  50
  51     @property
  52     def name(self):
  53         return self.dbname
  54
  55     def __str__(self):
  56         return 'Database connection object'
  57
  58     def __exit__(self, exc_type, exc_val, exc_tb):
  59         #self.connection.commit()
  60         self.cursor.close()
  61         self.connection.close()
  62