FHIR StructureMaps are machine-readable data transformation specifications . They are used in converting data from one format to another. For the SMART Guidelines, StructureMaps are used to convert data between QuestionnaireResponses and FHIR target profile instances. This is done in 2 steps:
Extract a Questionnaire Response into a Logical Model instance
This gets the data in a simple form that only depends on the data specification, and not on the profiles that are used
Extract the Logical Model instance into the FHIR resource instances
This process is done by 3 StructureMaps:
The StructureMap from QuestionnaireResponse to logical model instance;
The StructureMap from logical model instance to Resource instance ;
A grouping map that combines the two maps above to enable a single transform operation.
If this approach is used, the mapping is done by filling in the .definition element with the resource that is the target of the extraction - Patient, Observation, Encounter, etc.
the data extraction map from Questionnaire to Logical Model instances
the data extraction map from Logical Model instances to FHIR resources
the combined data extraction map that includes the 2 maps above and can process the extraction from Questionnaire to FHIR Resources
StructureMaps may be difficult to implement and debug. It is important to compile the maps frequently while authoring, and check the output in the QA of the publisher.
Reusing StructureMaps:
StructureMaps may be reused. For example, modular questionnaires (like Patient demographic modules) - which would use common transformations.
Output Criteria / Definition of Done
Mappings should create valid StructureMaps - including the necessary metadata.
the map should be correctly compiled and validated by the publisher - no QA errors
optional metadata should be added according to the spec
group names shall not contain spaces
StructureMaps for extraction must be tested to successfully transform the artifacts (for example, in a Questionnaire, the StructureMaps ust be tested to successfully obtain the intended resources from the QuestionnaireResponse).
All mapped elements and groups should be tested
All the dependencies of the StructureMap shall be in the IG or dependencies - SDC, base profiles, logical models, etc.
Change tracking
As with all FHIR Conformance resources, change management is critical. Do not set the version element of StructureMaps defined in the SMART Guideline, the version element will be set by the publication process. See the versioning topic for more information on change management.
