make the DBConnector class usable as a standalone object or in a context manager

database.py

@@ -1,10 +1,15 @@
+"""This module contains functionality for interacting with a PostgreSQL database. It will automatically handle error
+conditions (i.e. missing columns) without terminating the entire program. Use the :py:class:`DBConnector` class to
+handle database interactions, either as a standalone object or in a context manager."""
 import os
 import psycopg2
 
-DB_ADDRESS = os.environ['DB_ADDRESS']
-DB_USER = os.environ['DB_USER']
-DB_PASSWORD = os.environ['DB_PASSWORD']
-DB_NAME = os.environ['DB_NAME']
+
+DB_ADDRESS = os.getenv('DB_ADDRESS', 'localhost')
+DB_PORT = os.getenv('DB_PORT', 5432)
+DB_USER = os.getenv('DB_USER', 'postgres')
+DB_PASSWORD = os.getenv('DB_PASSWORD', '')
+DB_NAME = os.getenv('DB_NAME', 'postgres')
 
 
 class DBConnector:
@@ -15,16 +20,34 @@ class DBConnector:
        with DBConnector() as db:
            db.read()
     """
-    def __enter__(self):
-        self.conn = psycopg2.connect()
+    def _db_start(self):
+        self.conn = psycopg2.connect(
+            f"host={DB_ADDRESS} port={DB_PORT} dbname={DB_NAME} user={DB_USER} password={DB_PASSWORD}")
         self.cur = self.conn.cursor()
 
-    def __exit__(self):
+    def _db_stop(self):
         self.cur.close()
         self.conn.close()
 
+    def __init__(self):
+        self._db_start()
+
+    def __del__(self):
+        self._db_stop()
+
+    def __enter__(self):
+        self._db_start()
+
+    def __exit__(self):
+        self._db_stop()
+
     def _query(self, sql):
-        self.cur.execute(sql)
+        try:
+            self.cur.execute(sql)
+            result = self.cur.fetchall()
+        except psycopg2.DatabaseError as e:
+            result = []
+        return result
 
     def read(self, **kwargs):
         """Read rows from a database that match the specified filters.