ash_archival/documentation/topics/archival.md

Archival

Extension

This extension modifies a resource in the following ways.

1. Adds a private archived_at utc_datetime_usec attribute.
2. Adds a preparation that filters each action for is_nil(archived_at) (except for excluded actions)
3. Marks all destroy actions as soft?, turning them into updates (except for excluded actions)
4. Adds a change to all destroy actions that sets archived_at to the current timestamp
5. Adds a change that will iteratively load and destroy anything configured in d:AshArchival.Resource.archive|archive_related

Upgrading from < 1.0

Before 1.0 of this library, a base_filter was added to the resource to hide archived items. To retain the old behavior (which includes database structure), add the base_filter and base_filter_sql yourself.

Base Filter

Using a base_filter for your archived_at field has a lot of benefits if you are using ash_postgres, but comes with one major drawback, which is that it is not possible to exclude certain read actions from archival. If you wish to use a base filter, you will need to create a separate resource to read from the archived items. We may introduce a way to bypass the base filter at some point in the future.

To add a base_filter and base_filter_sql to your resource:

resource do
  base_filter expr(is_nil(archived_at))
end

postgres do
  ...
  base_filter_sql "(archived_at IS NULL)"
end

Benefits of base_filter

1. unique indexes will exclude archived items
2. custom indexes will exclude archived items
3. check constraints will not be applied to archived items

If you want these benefits, add the appropriate base_filter.

More

See the Unarchiving guide For more.