Take a look at the SQLAlchemy example provided.
Write SQLAlchemy model definitions for the two remaining tables in the database. Test your code with some simple queries, for example:
print(session.query(Model).count())
You don't need to implement foreign keys and other constraints at this moment.
Write a python script that, for two person names specified on the command line as arguments, will make them non-friends. This time do it SQLAlchemy-style :)
Tips:
- to delete some rows, just call
.delete()on a query set. - you need to make sure that either the connection is made in the autocommit mode, or you add an explicit commit after the delete operation; otherwise it will be rolled back and no change will be applied to the database
Idea one: extend our person model to have a second name column and a unique constraint spanning both first and second name.
Idea two: implement, using SQLAlchemy, the many-to-many mapping that is present in the database in table friends. Include backrefs for convenient access. SQLAlchemy provides a pretty decent documentation on how to do this.