enhance support for limits (RFC5) (#1856)

[tomkralidis]

Overview

This PR implements RFC5 to provide enhanced limit handling implementation in support of better definition and control on data query limiting.

Related Issue / discussion

#1856

Additional information

This PR needs PSC approval of RFC5 in order to be merged.

Dependency policy (RFC2)

• I have ensured that this PR meets RFC2 requirements

Updates to public demo

• I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • https://github.com/geopython/demo.pygeoapi.io/blob/master/services/pygeoapi_master/local.config.yml

Contributions and licensing

(as per https://github.com/geopython/pygeoapi/blob/master/CONTRIBUTING.md#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pygeoapi. I confirm that my contributions to pygeoapi will be compatible with the pygeoapi license guidelines at the time of contribution
• I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines

[totycro]

The implementation looks good to me!

With this change, the old limit setting is now ignored, so if anybody updates to the new version without changing the config, then the default limits apply again. We could detect this old setting and print an informational message .

[pvgenuchten]

very nice Tom, can we also port it to pycsw?

[webb-ben]

+1

[doublebyte1]

I think this is a really nice improvement! 👍🏽

Should the pygeoapi example configuration file also be changed?

pygeoapi/pygeoapi-config.yml

Line 44 in b4d3535

limit: 10

I would suggest changing it to a different number on default and max:

limits:
    defaultitems: 10  # applies to vector data
    maxitems: 100  # applies to vector data
    maxdistance: [x, y]  # applies to all datasets
    units: m  # as per UCUM https://ucum.org/ucum#section-Tables-of-Terminal-Symbols
    on_exceed: error  # one of error, throttle