On Tue, Aug 11, 2009 at 07:40:12AM +0200, Tom Coetser wrote: > class Member(SQLObject): > name = StringCol(alternateID=True) > roles = SQLRelatedJoin('Role', intermediateTable='member_role', > createRelatedTable=False) > > class Role(SQLObject): > name = StringCol(alternateID=True) > members = SQLRelatedJoin('Member', intermediateTable='member_role', > createRelatedTable=False) > > class MemberRole(SQLObject): > member = ForeignKey('Member', notNull=True, cascade=False) > role = ForeignKey('Role', notNull=True, cascade=False) > > When I call destroySelf() on a member though, I would like to **not** have > that member deleted if it still has any roles assigned to it. I tried setting > the cascade=False option in the intermediate table, but this does not help > because it looks like the base destroySelf() method automatically deletes any > RelatedJoins.
First thing I can guess your are using a backend that doesn't support CASCADE (SQLite?) With SQLite, you can CREATE a TRIGGER to prevent deletion from the intermediate table, but you have to do it yourself. .destroySelf() actually doesn't rely on the backend support for CASCADE; instead it uses it itself, but not on the RelatedJoin's intermediate table even if the table is declared explicitly. The simplest way I see is to override .destroySelf: class Member(SQLObject): name = StringCol(alternateID=True) roles = SQLRelatedJoin('Role', intermediateTable='member_role', createRelatedTable=False) def destroySelf(self): if list(self.roles): # or self.roles.count() raise RuntimeError('Cannot delete a member (%s) that has roles' % self.id) super(Member, self).destroySelf() class Role(SQLObject): name = StringCol(alternateID=True) members = SQLRelatedJoin('Member', intermediateTable='member_role', createRelatedTable=False) def destroySelf(self): try: self.members[0] except IndexError: super(Role, self).destroySelf() else: raise RuntimeError('Cannot delete a role (%s) that has members' % self.id) I showed three different ways to check for RelatedJoin. This of course only works with .destroySelf - other means will happily delete rows. Oleg. -- Oleg Broytmann http://phd.pp.ru/ p...@phd.pp.ru Programmers don't die, they just GOSUB without RETURN. ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ sqlobject-discuss mailing list sqlobject-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlobject-discuss