pygeoapi as a codelist registry

[pvgenuchten]

In the European Soil Community we're in the process of setting up a tool chain of tools to support our data workflows. For one aspect we're still looking for a good technical option. It is the publication of Codelists. In many cases common codelists are imported and extended to support a local use case, these extended codelists would need to be published in a simple method.

There are common tools for this task, such as:

• Skosmos (requires a sparql endpoint)
• Re3gistry (requires SOLR)
• GeoNetwork

Each of them a bit too hard to setup and manage

Some codelists actually have a geometry (consider a list of countries/regions/nature area's, etc), many do not. Still it would be interesting to publish every concept in a list as a feature in an OGC-API Features endpoint (do features need to have a geometry?).

I guess I would need to define a postgres/sqlite structure for codelists, to be consumed by one of the pygeoapi data providers.

A nice to have would be to have the json-ld be encoded using the SKOS ontology, which i think is possible with the current ld tooling.

An aspect of codelists is that they are usually nested (World-Africa-Nigeria-Lagos-Makoko). I wonder if pygeoapi has a mechanism for this. Concepts typically have sameAs, narrower, wider links to other concepts, I guess this can be managed in the link section.

[ksonda]

We have an open PR to allow for arbitrary JSON-LD templating that may be useful for this use case as well. #868

[pvgenuchten]

@ksonda, i tried your pr branch, but it was not clear how i could populate those json-ld templates, do you have some examples?

[ksonda]

You can see an example json-ld document here: https://reference.geoconnex.us/collections/gages/items/1000437?f=jsonld

This is generated by this template https://github.com/internetofwater/geoconnex.us/blob/master/pygeoapi/pygeoapi-skin-dashboard/templates/jsonld/ref-gages.jsonld

The template is a jinja template, that can map data fields like so:

"hyf:interpolative": {{ data.nhdpv2_REACH_measure }} , where nhdpv2_REACH_measure is a field in the data

The template is placed in a folder called jsonld within the templates directory (as set in the server config yaml)

Then, the template can be set at the collection level:

[pvgenuchten]

I'm going to give it a try, we should add such an example to docs

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