Sqlalchemy file organization

Question

Does anyone has any insight on organizing sqlalchemy based projects? I have many tables and classes with foreign keys, and relations. What is everyone doing in terms of separating classes, tables, and mappers ? I am relatively new to the framework, so any help would be appreciated.

Example:

classA.py # table definition and class A definition
classB.py # table definition and class B definition

### model.py
import classA,classB
map(classA.classA,clasSA.table)
map(classB.classB,clasSB.table)

Including mappers inside classA, and classB works, but poses cross import issues when building relations.. Maybe I am missing something :)

Answer 1

Take a look at Pylons project including SA setup.

meta.py includes engine and metadata objects

models package includes declerative classes (no mapper needed). Inside that package, structure your classes by relavance into modules.

Maybe a good example would be reddit source code:)

Answer 2

There are two features in SQLAlchemy design to avoid cross imports when defining relations:

1. backref argument of relation() allows you to define backward relation.
2. Using strings (model class and their fields names). Unfortunately this works for declarative only, which is not your case.

See this chapter in tutorial for more information.