Datasets created through dataset/add are redirected by CKAN

[AlexGilleran]

Problem description

Right now because new datasets end up with magda-ds as their id prefix, they're interpreted as being CKAN datasets by the CKAN redirection router (which assumes everything that doesn't start with ds- is a CKAN dataset, and as such end up looked up according to CKAN and 404ing.

We need to either make it so new datasets start with ds instead of magda-ds, or make the CKAN redirection smarter.

Problem reproduction steps

1. Create a new dataset
2. Go to that dataset in a browser
3. Hit refresh
4. 😢

Proposed New Flow (when CKAN redirection turned on)

• Request for CKAN dataset with CKAN slug comes in (e.g. /dataset/wyndam-bins)
• CKAN redirection module checks in registry if we have a dataset with that ID (wyndam-bins). If we do, just let it go through (no redirection). If we don't:
• Use CKAN api to look up dataset (e.g. /api/3/action/package_show?id=wyndham-bins). If we get a result, pull the actual CKAN ID off the CKAN dataset and use that to look up the matching dataset in the registry.
• If we can find a dataset in the registry with that CKAN id, redirect to that dataset
• If we can't, 404
• If the CKAN API 404s, return a 404 (or redirect to error, whatever the current behaviour is) as usual

[t83714]

We probably can exclude any the followings from CKAN -redirection:

• /dataset/ds-xxx
• /dataset/magda-ds-xxx
• /dataset/add
• /dataset/list

This will also solve the issue of having to disable ckan redirection in order to access add dataset function