Single file shuttle export

[zyxw59]

Summary of changes

Asana Ticket: 🏹 Single file describing a shuttle for use in gtfs_input

Adds a new endpoint, /api/shuttle/:id which returns a JSON description of a shuttle.

This endpoint only includes stop IDs, not names/locations/other info, since stops may be shared between multiple shuttle routes.

Reviewer Checklist

• Meets ticket's acceptance criteria
• Any new or changed functions have typespecs
• Tests were added for any new functionality (don't just rely on Codecov)
• This branch was deployed to the staging environment and is currently running with no unexpected increase in warnings, and no errors or crashes.

[zyxw59]

Once again, I would very much appreciate advice on the download button (where to put it, how to style it), since the current place I've put it (right next to the save/cancel buttons) is not great. Also it completely breaks when creating a new shuttle 🫠

[jzimbel-mbta]

Couple of comments on the controller setup, I'll take a look at the UI side as well shortly.

[zyxw59]

I decided to just include the download button on the index page, since you will generally need to save anyway, and saving takes you back to the index page.

[jzimbel-mbta]

From checking this locally, it looks like a shuttle with no shape assigned to it (which is allowed while it's in draft state, see Arrow.Shuttles.Shuttle.validate_for_active_status and validate_for_inactive_status) causes the download action to fail.

Probably other fields/relations that are allowed to be missing on draft shuttles would also cause the action to fail.

Given that, do you think it would make sense to:

1. hide the download button, and
2. have API.ShuttleController's show action send a 400 response

for inactive shuttles?

[zyxw59]

Yeah that sounds like a good idea