[production] ActiveRecord::InvalidForeignKey on collection deletion about mirador_sul

[drh-stanford]

Yeah the original data model had workspaces fully within collections -- they couldn't exist outside them. But sounds like we want to keep around workspaces. So, I agree that we need to modify the data model so that workspaces.collection_id can be null.

[jkeck]

Setting dependent: :destroy would destroy all the workspaces, which I would not be desired.

I believe we can set dependent: :nullify, however the sqlite3 adapter does not support foreign key so I can't write a meaningful test.

Another option would be to remove the foreign_key constraint in the database itself (through a migration) since we know that we want to retain workspaces regardless of whether the original collection exists or not.