Add a Wrapper For fhirPath expressions, cqf-calculatedValue, cqf-library and cqf-expression.

[RaaziaTarique]

Is your feature request related to a problem? Please describe.
FhirPathEngine, DataRenderer and related classes to evaluate fhirPath expressions, cqf-calculatedValue, cqf-library and cqf-expression will be used multiple time in the project so it's better to have central wrapper for these classes.

Following issues which may use this wrapper in the future:

#1040 (This wrapper is a Pre-Requisite)
#1033
#1059

Describe the solution you'd like
Add a wrapper in the common module.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
@jingtang10 proposed this solution in the SDK ticket discussion call held on 18th March, 2022 CC: @f-odhiambo

Would you like to work on the issue?
Please state if this issue should be assigned to you or who you think could help to solve this issue.

[jingtang10]

as a first step to speed up development, i think it's ok to create this new api as an internal api in the datacapture module. as a next step we can move it to the common module (which will require a separate release).

[ekigamba]

I recommend(draft) the following:

class FhirPathWrapper

functions:

• evaluate - Can be used by cqf-calculatedValue, cqf-express, calculatedExpression extensions
• evaluateToBoolean - Can be used by enableWhen extension

It can also be used in the FHIR Path variable issue at a later point

Most of these output either a boolean or a list of resources.

The wrapper can be extended to support constant extensions that need local support such as %questionnaire, qitem(), sum() etc defined here

FhirPathWrapper can also be modified to add support for other expressions as well such as answerExpression and others if needed.

@RaaziaTarique I don't know if this is what @jingtang10 wanted but I believe it's a start based on my understanding

Edited with @RaaziaTarique

[fredhersch]

@RaaziaTarique @jingtang10 has the approach here been resolved? Thanks

[f-odhiambo]

Updates on this

1. Min/Max validation Works for Date but not other data types - PR Restricting DatePicker to select date from outside the defined Range (Min/Max). Added support for fhir path expression in Min / Max Validators #1442 ready
2. calculated-expression - PR Implement calculated-expression extension #1380 ready
3. calculated-value - PR Restricting DatePicker to select date from outside the defined Range (Min/Max). Added support for fhir path expression in Min / Max Validators #1442 ready
4. Implement calculated-expression extension 1059 | variables -> PR Add variable Extension support #1328 ready
5. CQF Expression not implemented yet - Needs a discussion
   CC @maimoonak

[f-odhiambo]

CC @fredhersch @jingtang10

[jingtang10]

1. Restricting DatePicker to select date from outside the defined Range (Min/Max). Added support for fhir path expression in Min / Max Validators #1442 has comments to be addressed.
2. just left a review. also requested @joiskash to review.
3. that's the same PR as 1
4. just left a review
5. can you set up something please @maimoonak

[maimoonak]

The expressions support has a long list https://build.fhir.org/ig/HL7/sdc/expressions.html and https://build.fhir.org/ig/HL7/sdc/behavior.html. Some of the expressions discussed in current thread are below

• Date picker restrict -> Add ability to validate the min/max for Date on a FHIR Questionnaire  #1040 -> PR UNDER REVIEW Restricting DatePicker to select date from outside the defined Range (Min/Max). Added support for fhir path expression in Min / Max Validators #1442
• Initial expression -> initialExpression extension for advanced form behaviour #1033 -> PR MERGED -> Fix issue with empty context with initial expression #1228
• Variable support -> Add variable Extension support #1059 -> PR APPROVED -> Add variable Extension support #1328
• Calculated expression -> Support calculatedExpression #971 -> PR AWAITING PR 1328 (variables work) -> Implement calculated-expression extension #1380
• Calculated value -> PR READY -> Restricting DatePicker to select date from outside the defined Range (Min/Max). Added support for fhir path expression in Min / Max Validators #1442
• Answer expression -> Support for answerExpression extension #1039 -> PR UNDER REVIEW -> Answer expression extension implementation #1480
• EnableWhen expression -> Support enableWhenExpression #819 -> PR MERGED (long ago) -> enableWhenExpression Support #1294
• Candidate expression -> Add candidateExpression extension #1038 -> AWAITING PR 1480 (overlaps functionality)
• CQF Expression -> very vast range http://hl7.org/fhir/R4/extension-cqf-expression.html -> not implemented yet and no specific issue or use case exists/linked - Needs a discussion

@f-odhiambo @jingtang10 @Tarun-Bhardwaj

[f-odhiambo]

@fredhersch See the summery above on the related FHIRPath expression tickets

[jingtang10]

I think as a tracking issue this issue can be closed as the only item left is 1038.