Adding subcatalogs

[glaroc]

Hi, I'm wondering if it's possible to add sub catalogs to an existing catalog using stac-fastapi ? I can't seem to find any info on this.

[gadomski]

Answered on twitter (I refuse to call it X), but short answer, no.

Implementation would be non-trivial, especially if you wanted your sub-catalog to have its own set of STAC API endpoints. Even a basic implementation where the sub-catalog was static (no conformance classes), it would require adding a new out-of-spec endpoint to the server (e.g. /catalogs/{catalog-id}), which feels a little funny. There's no reason you couldn't add those endpoints yourself in your own app, but it doesn't feel quite in-scope for this project, to me at least.

I think the "correct" way to go about this would be to create a sub-catalog extension for the STAC API spec, which then could be implemented in stac-fastapi. That's much slower, however 😞.

Disclaimer: these are my opinions, others may think differently.

[glaroc]

Thank you for the clarification. It is kind of odd that the STAC API spec doesn't have any provision for this, while the STAC spec encourages organizing into subcatalogs. I understand how this would complexify the API however. I'll find another approach in the meantime.

[vincentsarago]

it would require adding a new out-of-spec endpoint to the server (e.g. /catalogs/{catalog-id}), which feels a little funny

we talk about this in tipg (OGC Features services) and technically having /catalogs/{catalog-id} is possible and shouldn't break the OGC spec for now, but the OGC Common draft Part 2, totally ignore the catalog part and mention only collection so maybe the catalog will break the spec at one point: https://ogcapi.ogc.org/common/overview.html

Right now, pgstac do not support catalogs either and I'm not sure if it's planned to support it (I guess it would require a lot of work).

maybe relevant opengeospatial/ogcapi-common#11 opengeospatial/ogcapi-common#298

[gadomski]

It is kind of odd that the STAC API spec doesn't have any provision for this, while the STAC spec encourages organizing into subcatalogs.

I agree. There's some fundamental differences between static catalogs and "API catalogs", and we don't tell that story particularly well at the moment (IMO). This is a topic that we'll be working on, at least from the documentation/story-telling side, during the upcoming STAC sprint.