DatabaseManager

The firewallfabrik.core.DatabaseManager class manages the in-memory SQLAlchemy database that holds all firewall objects, rules, and configuration data.

session() — Managed Session (Recommended)

dm.session() is a context manager that wraps an SQLAlchemy session in a transaction. The session is automatically committed when the context manager exits. Additionally, the current database state is pushed onto the undo stack if any data changes occurred.

with dm.session() as session:
    fw = session.query(Firewall).filter_by(name="fw1").one()
    fw.comment = "Updated comment"
# Transaction is committed and undo state is saved automatically

Use session() for all normal operations — it handles commit and undo tracking for you.

create_session() — Manual Session

create_session() returns a new SQLAlchemy session without automatic commit or undo tracking. You must manually commit the session and, if needed, create an undo save state via save_state().

session = dm.create_session()
fw = session.query(Firewall).filter_by(name="fw1").one()
fw.comment = "Updated comment"
session.commit()
dm.save_state()  # manually push to undo stack if needed

Use create_session() only when you need fine-grained control over transaction boundaries or want to avoid undo stack entries (e.g. during initial file loading).