FHIR Profiling: Changing Cardinality

FHIR Profiling

One key function of profiles is to modify the cardinality of an element. A profile can restrict an element's cardinality within its base structure.

The foundational FHIR structure defines the following types of cardinality:

• Optional array (0..*)
• Optional scalar (0..1)
• Required array (1..*)
• Required scalar (1..1)

With the following constraints:

• You cannot make a required element that is optional in the base profile. 
• You cannot convert an array element into a scalar if it exists as an array in the base profile. 
• You cannot change a scalar element into an array if it is defined as a scalar in the base profile.

Example of how to create a profile that makes the `Patient.name` field mandatory:

resourceType: StructureDefinition
url: http://example.org/fhir/StructureDefinition/patient-with-required-name
name: patient-profile
derivation: constraint
type: Patient
status: active
kind: resource
abstract: false
differential:
  element:
	- id: Patient.name
  	  path: Patient.name
  	  min: 1
  	  max: "*"

Create a profile in your own FHIR server