Referenced to contained resources are always validated, ignoring policyAdvisor

[dotasek]

If a reference is made to a contained resource, the core validator ignores the policyAdvisor.policyForContained method, and always validates the contained resource.

The logic appears to be here:

org.hl7.fhir.core/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java

Line 4273 in 3cf2a06

if (refType.equals("contained") || refType.equals("bundled")) {

A test case that illustrates this has been created here: FHIR/fhir-test-cases#216

[dotasek]

After discussion with @grahamegrieve, the policyForReference method should in fact supersede the policyForContained method, so this will not be changed.

However, the policyForReference method could be changed to include an enum as a parameter as follows:

ReferenceValidationPolicy policyForReference(
  IResourceValidator validator,
  Object appContext,
  String path,
  String url, 
  ReferenceType referenceType
);

public enum ReferenceType {
    CONTAINED,
    REMOTE,
    BUNDLED
  }

This would allow the implementation of IValidationPolicyAdvisor to define logic depending on the type of reference being validated.

[jdar8]

Hi @grahamegrieve,

Thanks for looking into this!
I think its great to make the validation behaviour for references configurable.

That being said, I'm a little curious as to why the policyForReference method should in fact supersede the policyForContained.
I just want to make sure that custom implementations of IValidationPolicyAdvisor (for example, one that will ignore validation for contained or bundled references) won't cause any unintentional consequences.

[grahamegrieve]

it's a lineball call, I think, but it's about least surprise. policyForContained concerns hitting a contained resource while iterating the resource directly. That's self evident

policyForReference concerns what do when hitting a reference, and deciding whether it should be validated or not

So when a reference points to a contained resource, which has precedence? I think that policyForReference should behave consistently irrespective of the location of the target, whether it's contained or not.

What would be good is to document this explicitly, so I'll do that