[Update 2013/08/22] As suggested on Reddit - for SQLAlchemy 0.8+ you should consider using the runtime inspection API instead of accessing low-level details directly.

Being able to convert SQLAlchemy objects into JSON is a useful feature, particularly for the purpose of convenient logging or returning them directly to a JavaScript frontend.

A function to do it can be as simple as the one below (extracted from Zato's source code):

400: Invalid request

The trick is to list all the columns using the model's ._sa_class_manager.mapper.mapped_table.columns attribute and fetch them one by one.

Note that you can also use anyjson which is a useful package that picks the best JSON library available and provides a uniform interface to all of them.