Pattern for avoiding accidental URL over-rides

[simonw]

Following #1517 I'm experimenting with a plugin that does this:

@hookimpl
def register_routes():
    return [
        (r"/(?P<db_name>[^/]+)/(?P<table_and_format>[^/]+?)$", Table().view),
    ]

This is supposed to replace the default table page with new code... but there's a problem: /-/versions on that instance now returns 404 Database '-' does not exist!

Need to figure out a pattern to avoid that happening. Plugins get to add their routes before Datasette's default routes, which is why this is happening here.

[simonw]

The solution that jumps to mind first is that it would be neat if routes could return something that meant "actually my bad, I can't handle this after all - move to the next one in the list".

A related idea: it might be useful for custom views like my one here to say "no actually call the default view for this, but give me back the response so I can modify it in some way". Kind of like Django or ASGI middleware.