Profile validation fails even when constraint is satisfied

[rahul1]

User Driven: https://discord.com/channels/905144809105260605/1194887284537954304/1194887284537954304

Repro

1. Upload the following Structure definition to your project: test.fhir.json

2. Try to save the following encounter: test-encounter.json

Actual Behavior

Receive the following error:

Expected Behavior

The Encounter has a valid identifier that satisfies the constraint, so we would expect to pass

[codyebberson]

@mattwiller - My first instinct would be to test the identifier.where(a = 'x' and b = 'y') syntax in the fhirpath project directly

[codyebberson]

Putting together a fix now. There is one issue in our schema validator, and I think perhaps one issue with the user's StructureDefinition.

First, in our schema validator, we're not currently validating "root" constraints (i.e., at the top level, on the Encounter element definition). So if you add a root constraint such as "identifier.where(system='http://example.com' and value='123').exists()", it would be ignored.

So, I assume the user may have tried to put that constraint on the Encounter.identifier element. In that case, the constraint expression should omit "identifier", and simply be "where(system='http://example.com' and value='123').exists()", because the context value is the identifier array, not the Encounter.