FHIR DataRequirement metadata type

Question

I am implementing a CDS system, and I would like to use the DataRequirement type to ask for additional information. However, I am having some difficulties to understand the filter elements ("codeFilter" and "dateFilter").

For example, the property "path" of the filter elements is of string type, but what is the format to specify this path? I have been searching some examples from the FHIR specification, and I've tried to follow the "path" in the resource object. I attach below an image with an example and the specification of the resource "MedicationRequest" that is being addressed in this example. Can anyone explain me over this example how to traverse throw the elements? What is the element "code" from the path refering to?

example DataRequirement.codeFilter

Can anyone help me with this issue? Examples of use would be appreciated!

Thanks in advance.

Answer 1

It's referring to the FHIRpath query - see spec.

Answer 2

The path element is a FHIRPath, but for simplicity, it assumes the ability to traverse references. Without that, the dereference would have to be explicit, as in:

medicationReference.resolve().code

The spec isn't clear on this, so I will submit a tracker to add that clarification.