Link to specific version for yanked crate during search

[Tyrubias]

Queries the database during search to check if a release is yanked. If it is, link to the specific version rather than simply latest to avoid seeing the "The requested version does not exist" message.

Closes #2373

[Tyrubias]

I haven't been able to test this locally because I'm still in the process of manually seeding my local database with data. If anyone has advice on how to do this, I would appreciate the help 😄

[syphar]

Thank you for the help!

From the code I would say this works, but we have some edge cases to think about.

Looking at #1691 and #2239, we want /latest/ in the URL for all cases where possible.

In #2373 we say that we only want the exact version here, when all versions for a crate are yanked. Or to be more specific: we want an exact version here for all the cases where /latest/ would lead to a 404, while versions exist. Looking at our match_version logic the only case where we would get a 404 here is when all versions are yanked.

This is why initially I was thinking about actually checking all releases in the search-handler SQL, so see if all of them are yanked, and giving this information to the template to render the specific version then.

Now back to your approach:
releases.latest_version_id is set after each build for a crate, so the latest non-pre and non-yanked version if these exist, or the newest version. So while in many cases the latest_version_id is only yanked, when all releases are yanked, there might be cases around pre-releases where this isn't true. Also, looking through our logic here I see an edge case when a release is directly yanked, where we don't update latest_version_id accordingly.

In the end, about test-data:
the easiest way to get in valid test-data is to manually run some builds on releases, if that's easily possible.

[Tyrubias]

I changed the search handler to retrieve all versions, then set a flag if all the versions are yanked. To be honest, I'm not entirely happy with this approach, so if you have any tips for how to improve this I would greatly appreciate it.

I think this addresses the edge cases because it appears that when everything but pre-releases are yanked, the pre-release is set as the latest version (and that's the one we default to pulling with this code).

[Tyrubias]

Also are there any tests I should be adding for this change?

[syphar]

Thank for for your continued work on this! and sorry for the delayed response from my side.

Also are there any tests I should be adding for this change?

We have a generic search test which could be extended. You would add a new fake crate to the mocked crates.io response, create a yanked fake release in the db, and check if the link does include the explicit version.