Forum OpenACS Q&A: Dropping a package

Hello everybody,

I am having big problems dropping packages when some data has been inserted into the acs_objects from the package prior to trying to delete the package.

I've written working drop scripts which clean up everything properly but when i go to the http://localhost/acs-admin/apm/package-delete page and try to delete the package it always has a foreign key error with the acs_objects table because it attempts to delete the package first

i.e
ERROR: update or delete on "acs_objects" violates foreign key constraint "acs_objects_context_id_fk" on "acs_objects"

SQL:
select apm_package__delete('867');

If it ran my drop scripts first this wouldn't be a problem. Im not sure what i need to do to get around this problem

Please help.

Kind regards,
Geoff.

Well the notes package for one doesn't work but also a package i've written myself based off the drop scripts from notes. Any package that has written to the acs_objects table causes it to fail on the drop.

Perhaps you need to do:

delete from acs_objects where object_type='notes';

or similar, you can look the categories package or another like example. If you solve the bug send it to https://openacs.org/bugtracker/openacs/.

Regards

Here is how the process works.

One install of a package, the files in package-key/sql/dbname/ *-create.sql are executed.

These are executed only once when the package is first installed.

When you uninstall the package completey all package instances are removed, and the package will be unavailable for use. This is the only time the *-drop.sql scripts are run.

When you want to delete one package instance, the drop scripts are not run. There are APM Tcl callbacks that can be executed when a package is deleted. See /acs-admin/apm/ click on a packgae name, then on #
# Tcl Callbacks (install, instantiate, mount)

There is a callback for the following events:

before-install
after-install
before-upgrade
after-upgrade
before-uninstall
after-instantiate
before-uninstantiate
after-mount
before-unmount

In the case of deleting one package instnace the callback to use is before-uninstantiate. In the before-uninstantiate callback, all objects that refer to the package_id of the pakcage instance must be removed or otherwise dereferenced from that package_id. At this time most packages do not handle this correctly. Basically what needs to be done is run code similar to the drop.sql script just for one package_id.

If you visit the callback page for one package, you can get more information about how the callbacks work, and when they are executed.

All packages should implement the before uninstantiate callback to allow delete of package instances.