def add_or_update_activity(project_id, pgm_group, session_id=0, activity_id=0):
"""
Add activity to database or update it if it exists already.
:param project_id: ID of the project Activity is associated with.
:type project_id: Integer
:param pgm_group: The PGM Group number.
:type pgm_group: Integer
:param session_id: ID of the session Activity is associated with.
:type session_id: Integer
:param activity_id: ID of the activity.
:type activity_id: Integer
:returns: Activity ID of the added activity.
:rtype: Integer
"""
project = Project.get_by_id(project_id)
session = Session.get_by_id(session_id) if session_id > 0 else None
_logger().debug('ADD OR UPDATE. Session {0}: {1!r}'.\
format(session_id, session))
if activity_id > 0:
try:
activity = Activity.get_by_id(activity_id)
activity.project_id = project_id
activity.session_id = session_id
except NoResultFound:
activity = Activity(project, session)
else:
activity = Activity(project, session)
activity.active = pgm_group
activity.update()
_logger().debug('ACTIVITY ID : {0} (session_id {1})'.\
format(activity.id, activity.session_id))
return activity.id
