Workflow library alpha02 crashes when PlanDefinition has an .action.condition?

[williamito]

Describe the bug
I am able to generate a care plan using a minimal Plan Definition. When I add a condition to the plan definition, the app crashes instead with

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean org.hl7.fhir.r4.model.Base.isResource()' on a null object reference
at org.hl7.fhir.r4.utils.FHIRPathEngine.evaluate(FHIRPathEngine.java:525)
at org.hl7.fhir.r4.hapi.fluentpath.FhirPathR4.evaluate(FhirPathR4.java:31)
at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.evaluateConditionOrDynamicValue(PlanDefinitionProcessor.java:568)
at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.meetsConditions(PlanDefinitionProcessor.java:458)
at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.resolveAction(PlanDefinitionProcessor.java:174)
at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.resolveActions(PlanDefinitionProcessor.java:161)
at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.apply(PlanDefinitionProcessor.java:136)
at com.google.android.fhir.workflow.FhirOperator.generateCarePlan(FhirOperator.kt:241)
at com.example.enginetest.MainActivity$onCreate$1.invokeSuspend(MainActivity.kt:117)

Component
Workflow Library

To Reproduce
See https://github.com/williamito/fhir-engine-test/blob/main/app/src/main/java/com/example/enginetest/MainActivity.kt

It works with

{
  "resourceType": "PlanDefinition",
  "id": "Test-PlanDefinition",
  "status": "active",
  "action": [
    {
      "definitionCanonical": "http://example.org/ActivityDefinition/ADTest"
    }
 ]
}

And crashes with

{
  "resourceType": "PlanDefinition",
  "id": "Test-PlanDefinitionCondition",
  "status": "active",
  "action": [
    {
      "condition": [
        {
          "kind": "applicability",
          "expression": {
            "language": "text/fhirpath",
            "expression": "true"
          }
        }
      ],
      "definitionCanonical": "http://example.org/ActivityDefinition/ADTest"
    }
 ]
}

I also tried variations of "language": "text/cql" and got a similar crash from the CQL libraries complaining about a missing resource.

Expected behavior
Trivial condition evaluates to true and care plan is generated.

[williamito]

In case it helps, the actual intent of the condition expression was to check Patient.gender = 'female' which has the same crash. I ended up trying true to make sure I wasn't messing up the use of fhirpath.

[jingtang10]

Bryn's suggestion: try use text/cql-expression as the language of the expression in the condition.

can you plz try william?

[williamito]

This is the result of using "language": "text/cql-expression" -

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.enginetest, PID: 3496
    java.lang.NullPointerException: Attempt to invoke virtual method 'boolean org.hl7.fhir.r4.model.Parameters$ParametersParameterComponent.hasValue()' on a null object reference
        at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.getParameterComponentByName(PlanDefinitionProcessor.java:540)
        at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.evaluateConditionOrDynamicValue(PlanDefinitionProcessor.java:585)
        at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.meetsConditions(PlanDefinitionProcessor.java:458)
        at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.resolveAction(PlanDefinitionProcessor.java:174)
        at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.resolveActions(PlanDefinitionProcessor.java:161)
        at org.opencds.cqf.cql.evaluator.plandefinition.r4.PlanDefinitionProcessor.apply(PlanDefinitionProcessor.java:136)
        at com.google.android.fhir.workflow.FhirOperator.generateCarePlan(FhirOperator.kt:241)
        at com.example.enginetest.MainActivity$onCreate$1.invokeSuspend(MainActivity.kt:118)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loopOnce(Looper.java:201)
        at android.os.Looper.loop(Looper.java:288)
        at android.app.ActivityThread.main(ActivityThread.java:7842)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
    	Suppressed: kotlinx.coroutines.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@263a27d, Dispatchers.Main.immediate]

[vitorpamplona]

This is a bug in FhirPath evaluations with a null base in the FHIR Core: PR: hapifhir/org.hl7.fhir.core#1015

We will need to wait for the solution to trickle down into HAPI, then the cql-evaluator, then workflow.

[williamito]

It looks like Vitor's fix was reverted: hapifhir/org.hl7.fhir.core#1017

I'm not sure why, I don't see any discussion on github other than it was reverted by request of Grahame Grieve.

This bug does significantly hamper care plan generation, as encoding the conditional logic in FHIR is a primary value. I'm not sure what the timeline is for the fix to trickle down to the workflow library, is there a workaround besides implementing it in application logic?

[vitorpamplona]

They are debating if that is the way it should be or not.

The bug should only happen in FhirPath expressions. CQL expressions should work.

[williamito]

It seems to also happen with CQL expressions though: please see crash in #1733 (comment)

[vitorpamplona]

Different error, though. I didn't get there yet.

[vitorpamplona]

The CQL/expression error is fixed on the CQL Evaluator 2.3. I am making a PR to upgrade the workflow

[williamito]

From Vitor re: CQL

There is a bug in the version of the Jackson processor that HAPI is using hapifhir/hapi-fhir#4308

That bug only happens when using graddle. The evaluator was migrated to the new buggy version and now we need to wait for hapi to upgrade first, update the evaluator and only then update the workflow.