DOI modification check should be case-insensitive

[marksparkza]

A change in case of a DOI should not trigger "The DOI has been published and cannot be modified" error. This happened recently (on dev) with a change in case of DOIs coming from the Observations DB.

For comparison, the DOI conflict check is case-insensitive. This prevents records from being created or updated and assigned a DOI that already belongs to another record but would otherwise pass the unique constraint due to being differently cased.

The published DOI modification check was probably left as case-sensitive because of the foreign key from published_record to record (with ON UPDATE RESTRICT ON DELETE RESTRICT). We probably don't want ON UPDATE CASCADE - this would defeat the 'immutability of published DOIs' that this table provides.

The published DOI modification check should be case-insensitive. However, we then need to also ignore DOI case changes in terms of updating record, otherwise we'd trigger the on update restriction in the DB layer and throw a 500 back to the client. This means never updating DOIs from data providers if they are just changing case. But DOIs are case-insensitive, so in principle this is not a problem.

Data providers might expect a DOI case change to propagate to a published record, but ultimately it's a policy decision for the ODP as to whether to publish DOIs in uppercase, lowercase, or not to care. Currently, we don't care, but this should be reviewed.

[marksparkza]

The uniqueness constraints on record.doi and published_record.doi should perhaps be made case-insensitive. This would be strictly more correct from a DB perspective, but we'd still need the case-insensitive DOI checks in the API layer to prevent triggering DB update restrictions. And this would further cement the need for a policy on DOI case for publishing.

[marksparkza]

Following discussion with the curation team, the decision is that it's not necessary to standardise DOI case for publishing. DOIs are officially case-insensitive, after all. A catalogue client is still free to makes its own decision regarding DOI rendering.