persist the default admin set id in the database

[elrayle]

Fixes #5261

This also makes the default admin set and id accessible through Hyrax.config. The first time it is accessed, the default admin set will be created if it doesn’t already exist. If the default admin set id saved in the database changes, it will reset the instance variable in Hyrax.config that caches the default admin set.

Final Design

The final design is somewhat different than the one proposed in #5261.

It addresses challenges:

• for existing apps, it will use the existing default admin set identified by DEFAULT_ID
• allow the default admin set to be created with an assigned id (required for postgres adapter)
• cache the default admin set and id so it doesn't have to be retrieved from the persistent store every time it is referenced
• saves the id in the database so it is remembered between restarts of the system and other events that will wipe the cached version
• the plumbing to allow for the identified default admin set to be changed is in place, but not surfaced in the UI. This is prep for having this functionality in the future.

Supporting changes:

• persistance of the default admin set id is handled by model Hyrax::DefaultAdministrativeSet which saves the default admin set id in the database
• runtime caching is handled by Hyrax.config.default_admin_set which caches the default admin set in @default_admin_set instance variable the first time it is accessed. It can be forced to update by calling Hyrax.config.reset_default_admin_set. Hyrax.config.default_admin_set_id` provides a shortcut to the default admin set's id.
• Hyrax::AdminSetCreateService.find_or_create_default_admin_set uses Hyrax::DefaultAdministrativeSet to make sure the id is persisted. This maintains this method as "the" way to create the default admin set. Using this method, the persisted and cached versions of the default admin set will be refreshed if needed.

@samvera/hyrax-code-reviewers

[elrayle]

When run with the test app, the id continues to be assigned as the DEFAULT_ID.

Testing in nurax-pg with a freshly migrated database for both checks.

Check 1: creating with the rake task

This is the historical way to create default admin set for Hyrax apps.

$ bin/rails hyrax:default_admin_set:create
Successfully created default admin set

Confirm in rails console...

>> Hyrax::DefaultAdministrativeSet.first.default_admin_set_id
=> "5418df25-4cbd-4e2a-8bc7-c85e135bd5fc"
>> Hyrax::AdminSetCreateService.find_or_create_default_admin_set.id.to_s
=> "5418df25-4cbd-4e2a-8bc7-c85e135bd5fc"
>> Hyrax.config.default_admin_set_id
=> "5418df25-4cbd-4e2a-8bc7-c85e135bd5fc"

Check 2: creating first time accessed when one doesn't exist

Cleared db before running second check.

Create and confirm in rails console...

>> Hyrax::DefaultAdministrativeSet.first
=> nil
>> Hyrax::AdminSetCreateService.find_or_create_default_admin_set.id
=> "7f0e2948-a90b-47ca-8871-424b81b07cb8"
>> Hyrax::DefaultAdministrativeSet.first.default_admin_set_id.to_s
=> "7f0e2948-a90b-47ca-8871-424b81b07cb8"
>> Hyrax.config.default_admin_set_id
=> "7f0e2948-a90b-47ca-8871-424b81b07cb8"