_elements

include or exclude specific resource attributes in search result

A client can request a specific set of elements to be returned as part of a resource in the search results using the _elements parameter:

GET [base]/Patient?_elements=birthDate,name.given,address.city
# resp
resourceType: Bundle
type: searchset
entry:
- resource:
birthDate: '1991-11-08'
name: [{ given: [Marat] }]
address: [{city: 'Tokio'}]
resourceType: Patient
- resource:
name: [{given: [Abram]}]
resourceType: Patient
- resource:
birthDate: '1965-03-29'
name: [{ given: [John] }]
address: [{city: 'Los Angeles'}]
resourceType: Patient

The _elements parameter consists of a comma-separated list of element paths such as. Only element paths that are listed are to be returned. The list of elements does not apply to included resources.

Exclude

If you want to exclude specific elements you can prefix it with - sign:

GET /Patient?_elements=-text,-identifier

Nested elements

You can select or exclude nested elements using dot separated path to element:

GET /Patient?_elements=name.given,name.family

Elements and (rev)includes

_elements parameter is not applied to included resources. If you want to filter included resources elements - prefix element path with resourceType. For example:

GET /Encounter?_include=patient&_elements=id,type,Patient.name

Result will contain id and type elements from Encounter and name from Patient. Prefix with - will exclude elements (for example -Patient.identifier - will exclude identifier from patients)