Check if previous/next page is hidden to show previous/next buttons

[LZRS]

IMPORTANT: All PRs must be linked to an issue (except for extremely trivial and straightforward changes).

Fixes #2568

Description
Change getQuestionnairePages to only return questionnaire pages from QuestionnaireItems that have extension

        {
          "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-itemControl",
          "valueCodeableConcept": {
            "coding": [
              {
                "system": "http://hl7.org/fhir/questionnaire-item-control",
                "code": "page",
                "display": "Page"
              }
            ]
          }
        }

Alternative(s) considered
Have you considered any alternatives? And if so, why have you chosen the approach in this PR?

Type
Bug fix

Screenshots (if applicable)

Checklist

• I have read and acknowledged the Code of conduct.
• I have read the Contributing page.
• I have signed the Google Individual CLA, or I am covered by my company's Corporate CLA.
• I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach.
• I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the style guide of this project.
• I have run ./gradlew check and ./gradlew connectedCheck to test my changes locally.
• I have built and run the demo app(s) to verify my change fixes the issue and/or does not break the demo app(s).

[MJ1998]

We need to include contiguous set of items not with page extension into another page.

"If there are items at the same level as a 'page' group that are listed before the 'page' group, they will be treated as a separate page"
Reference - https://build.fhir.org/ig/HL7/fhir-extensions//CodeSystem-questionnaire-item-control.html

So if the questionnaire looks like -

{
  itemWithNoPageExtension1, 
  itemWithPageExtension2, // have nested items
  itemWithPageExtension3,
  itemWithNoPageExtension4,
  itemWithNoPageExtension5,
  itemWithNoPageExtension6,
  itemWithPageExtension7,
}

The pages would look like following:-

{
  page1: {
  	itemWithNoPageExtension1,
  },
  page2: {
  	itemWithPageExtension2
  },
  page3: {
  	itemWithPageExtension3
  },
  page4: {
  	itemWithNoPageExtension4,
  	itemWithNoPageExtension5,
  	itemWithNoPageExtension6
  },
  page5: {
  	itemWithPageExtension7
  }
}

[LZRS]

We need to include contiguous set of items not with page extension into another page.

"If there are items at the same level as a 'page' group that are listed before the 'page' group, they will be treated as a separate page" Reference - https://build.fhir.org/ig/HL7/fhir-extensions//CodeSystem-questionnaire-item-control.html

So if the questionnaire looks like -

{
  itemWithNoPageExtension1, 
  itemWithPageExtension2, // have nested items
  itemWithPageExtension3,
  itemWithNoPageExtension4,
  itemWithNoPageExtension5,
  itemWithNoPageExtension6,
  itemWithPageExtension7,
}

The pages would look like following:-

{
  page1: {
  	itemWithNoPageExtension1,
  },
  page2: {
  	itemWithPageExtension2
  },
  page3: {
  	itemWithPageExtension3
  },
  page4: {
  	itemWithNoPageExtension4,
  	itemWithNoPageExtension5,
  	itemWithNoPageExtension6
  },
  page5: {
  	itemWithPageExtension7
  }
}

Ah okay, makes sense. Probably we'd then need to make changes to our questionnaires, thanks

[FikriMilano]

@LZRS does this change handle the following use case?

if the first page is by default, hidden using an extension, while the user is in the second page, the previous button should be hidden

[LZRS]

@LZRS does this change handle the following use case?

if the first page is by default, hidden using an extension, while the user is in the second page, the previous button should be hidden

Yes, so far the changes in this PR handle that but the ongoing discussions were on whether it should be hidden, since it's also treated as a 'page', or if we should instead handle it by throwing an exception

[FikriMilano]

@LZRS
I mean, what if the first page has the page extension? but the page item is hidden using an extension.

In the second page, which also has a page extension, the previous button needs to be hidden.

Can this change handle that?

[LZRS]

@LZRS I mean, what if the first page has the page extension? but the page item is hidden using an extension.

In the second page, which also has a page extension, the previous button needs to be hidden.

Can this change handle that?

Yeah, it handles that

[FikriMilano]

Here's some updates about the issue in dealing with pages, by @MJ1998
https://chat.fhir.org/#narrow/channel/179255-questionnaire/topic/Rendering.20of.20pages.20when.20page.20extension.20is.20absent.20in.20items/near/481103016

[FikriMilano]

@MJ1998 @jingtang10 have you decided whether we should make the implementation more relaxed?

[LZRS]

@FikriMilano @MJ1998 Reviewing the current existing implementation, Sibling items to a page extension group are treated as page even though they may not be of typegroup.

{
  page1: {
  	itemWithNoPageExtension1
  },
  page2: {
  	itemWithPageExtension2
  },
  page3: {
  	itemWithPageExtension3
  },
  page4: {
  	itemWithNoPageExtension4
},
page5: {
  	itemWithNoPageExtension5
},
page6: {
  	itemWithNoPageExtension6
  },
  page7: {
  	itemWithPageExtension7
  }
}

The spec has also been updated

If a group item has this itemControl value, then all sibling items SHALL also be of type group and also have an itemControl value of 'page', 'header', or 'footer'. Form fillers SHOULD raise an error if a Questionnaire fails to adhere to this requirement.

IMO, it feels the current implementation is already relaxed and wouldn't necessarily crash

In the PR, I have just updated to check that the previous or next button is not hidden, to show the previous/next button

[MJ1998]

LGTM. Approving with one small NIT.