SQLAlchemy: cascade delete

Question

I must be missing something trivial with SQLAlchemy\'s cascade options because I cannot get a simple cascade delete to operate correctly -- if a parent element is a deleted,

Answer 1

Answer by Stevan is perfect. But if you are still getting the error. Other possible try on top of that would be -

http://vincentaudebert.github.io/python/sql/2015/10/09/cascade-delete-sqlalchemy/

Copied from the link-

Quick tip if you get in trouble with a foreign key dependency even if you have specified a cascade delete in your models.

Using SQLAlchemy, to specify a cascade delete you should have cascade='all, delete' on your parent table. Ok but then when you execute something like:

session.query(models.yourmodule.YourParentTable).filter(conditions).delete()

It actually triggers an error about a foreign key used in your children tables.

The solution I used it to query the object and then delete it:

session = models.DBSession()
your_db_object = session.query(models.yourmodule.YourParentTable).filter(conditions).first()
if your_db_object is not None:
    session.delete(your_db_object)

This should delete your parent record AND all the children associated with it.