REMS-260 Prefetch hydration

[KeeyanGhoreshi]

Describe your changes

This adds some basic prefetch hydration to the REMS CRD app. The prefetch hydration checks to see which prefetch elements are missing, then uses the definition of the hook to make the requests for prefetch data itself with the EHR url present in the hook it receives.

Possible next steps might include allowing the hydration app to accept different types of hooks. For example, if we wanted to add order-select, there would need to be some logic to check the type of hook received, and based on that, send the correct prefetch structure to the hydrator.

To see this in action, you will need to use the branch of similar name on request-generator hydrate-prefetch which includes a change to remove request from the prefetch. This is because, technically, the prefetch token used in the request is not valid according to the CDS hooks specification. Prefetch tokens are only allowed to be one level deep, which means something like context.draftOrders.medicationRequest is not valid. To access this information, we would need to redefine the definition of our rems-order-sign hook to include medicationRequestId as a top-level property of the context object. Or we just need to search through the draftOrders for the information we want.

With the correct branch of the request generator, you can send a request without a prefetch by opening settings and unselecting the "include prefetch" option. This will send a hook with no prefetch element, and CRD will instead hydrate it itself, resulting in the prefetch still having the appropriate resources.

Issue ticket number and Jira link

REMS-260

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[kennyEung]

The Linter is throwing a couple of warning messages that would seem useful to resolve. Though not critical.