PostgreSQL, Second Edition

Client 2—Adding Error Checking

If you look back to line 7 of Listing 17.1, you'll notice that client1 calls pgdb.connect() to connect to a PostgreSQL server. If anything goes wrong during this function call, Python will print a stack trace and abort the program.

If you want to intercept a connection error, you must wrap the call to pgdb.connect() in a try/except block. The Python DB-API specification defines a hierarchy of exception types that a conforming implementation may throw. The most general exception type is StandardError. All other DB-API exceptions are derived (directly or indirectly) from StandardError.

Listing 17.2 shows client2.py. This client calls pgdb.connect() inside of a try/except block and catches any exceptions derived from ...