Adding notes demo code.

mikeckennedy · mikeckennedy · commit f5949a2bd412 · 2022-12-19T17:11:00.000-08:00
diff --git a/code/ch02-error-messages/notes.py b/code/ch02-error-messages/notes.py
@@ -0,0 +1,53 @@
+import sys
+from typing import Optional
+
+
+class DbException(Exception):
+    pass
+
+
+class DbConnectionException(DbException):
+    pass
+
+
+def connect_to_db(conn_str, server: Optional[str] = None, port: Optional[int] = None):
+    if "server=" in conn_str or "port=" in conn_str:
+        raise DbConnectionException("Connection string is malformed")
+
+    conn_str += f"&server={server}&port={port}"
+
+    print(f"Connecting to DB with {conn_str}")
+
+
+def setup_app():
+    # conn_str = "mongo://user=mk&password=a&database=talkpython"
+    conn_str = "mongo://user=mk&password=a&database=talkpython&port=1000"
+    server = "localhost"
+    port = 27017
+
+    try:
+        connect_to_db(conn_str, server, port)
+    except DbException as dbe:
+        dbe.add_note("Cannot specify server or port explicitly and include it in the connection string.")
+        dbe.add_note("Amend the connection string and try again.")
+        raise
+
+
+def main():
+    # You'll see the notes here
+    # setup_app()
+
+    try:
+        setup_app()
+        print("App ready")
+    except Exception as x:
+        print("Error starting app:")
+        print(f'{type(x).__name__}: {x}')
+        for n in x.__notes__:
+            print(f"NOTE: {n}")
+
+        sys.exit(7)
+
+
+if __name__ == '__main__':
+    main()
