FHIR Chat · ValueSet `regex` op · terminology

Stream: terminology

Topic: ValueSet `regex` op

Michael Lawley (Feb 24 2021 at 00:16):

The documentation on ValueSet filters where op = regex is incomplete.
Two key issues are:

1. what flavour of regex?
2. are these regex's implicitly "anchored"? More specifically, is it expected that the regex must match the entire value or not? Looking at the definition of http://hl7.org/fhir/ValueSet/iso3166-1-3, which is documented as:

   This value set defines the ISO 3166 Part 1 3-letter codes

and has the following filter:

        "include" : [{
          "system" : "urn:iso:std:iso:3166",
          "filter" : [{
            "property" : "code",
            "op" : "regex",
            "value" : "[A-Z]{3}"
          }]
        }]

it would appear so. i.e., the regex should be interpreted as ^[A-Z]{3}$

This then raises the question of what the regex ^[A-Z]{3}$ should match? i.e., are the ^ and $ characters to be treated literally or not (hence question 1. what flavour of regex)

Grahame Grieve (Feb 24 2021 at 02:17):

yes it should be understood to be anchored. I do not know how to resolve the falvor question

Rob Hausam (Feb 24 2021 at 02:21):

In lieu of deciding on a single flavor for everyone, the server could (should) at least declare which flavor it supports?

Last updated: Apr 12 2022 at 19:14 UTC