First-Class Extensions

First-class extension as Zen profile
In order to define first-class extension as zen profile you should follow the steps below:
1.​Initialize zen project and add additional IGs if necessary
2.Define your custom first-class extension.  For syntax and more examples refer to this page.
{ns my-zen-project
 import #{zen.fhir
          hl7-fhir-r4-core.string
          hl7-fhir-r4-core.dateTime
          hl7-fhir-r4-core.uri}
​
 MyPatient
 {:zen/tags #{zen/schema zen.fhir/profile-schema}
  :zen/desc "Patient resource schema with first-class extension definition examples"
  :zen.fhir/version "0.5.20"
  :confirms #{zen.fhir/Resource}
  :zen.fhir/type "Patient"
  :zen.fhir/profileUri "urn:profile:MyPatientProfile"
  :type zen/map
  
  :keys {:meta {:type zen/map
                :keys {:tenant-id
                       {:confirms #{hl7-fhir-r4-core.string/schema}
                        :zen/desc "Patient.meta.tenant-id first-class extension"
                        :fhir/extensionUri "http://tenant-id-extension-url"}}}
​
         :form {:type zen/vector
                :zen/desc "Patient.form.[*] array first-class extension"
                :every {:confirms #{hl7-fhir-r4-core.uri/schema}
                        :fhir/extensionUri "http://patient-form-url"}}
​
         :info {:type zen/map
                :zen/desc "Patient.info nested first-class extension"
                :fhir/extensionUri "http://patient-info"
                
                :keys {:registration {:confirms #{hl7-fhir-r4-core.dateTime/schema}
                                      :zen/desc "Patient.info.registration 
                                                 extension.url deduced from key"}
                       
                       :referral {:confirms #{hl7-fhir-r4-core.uri/schema}
                                  :fhir/extensionUri "http://patient-info-referral"
                                  :zen/desc "Patient.info.referral
                                             extension.url is specified"}}}}}}
3.Fix :zen.fhir/version errors if needed
In order to fix this error, provide IG bundle with the matching zen FHIR version.
Error message example
Expected '0.5.8', got '0.4.9'
path: [:zen.fhir/version]
4.:fhir/extensionUrl property value
Note: :fhir/extensionUri "http://tenant-id-extension-url" it is equivalent of the extensionUrl field of the Attribute resource it is used to form FHIR extension. And also it is important to use FHIR type instead of plain zen type, i.e. use :confirms #{hl7-fhir-r4-core.string/schema} instead of :type zen/string.
Define new extension
In Aidbox, you can define first-class extensions using the custom resource Attribute.
Let's create an extension definition of type Reference in the REST Console of Aidbox:
Create new extension in the Aidbox format:
PUT /Attribute/ServiceRequest.requestedOrganizationDepartment
​
description: Department in the organization that made the service request
resource: {id: ServiceRequest, resourceType: Entity}
path: [requestedOrganizationDepartment]
type: {id: Reference, resourceType: Entity}
refers: 
  - Organization
extensionUrl: urn:extension:requestedOrganizationDepartment
description - string.
Attribute text description
resource - required, Reference(Entity).
Reference to a target resource type
path - required, array of strings.
Path to a new attribute location in the target resource type
type - Reference(Entity).
Type of data stored in this attribute. Can be any primitive or complex type.
If omitted, treated as BackboneElement, i.e. a complex-type object with structure defined via other Attributes relying on this attribute in their path
isCollection - boolean.
Whether the attribute is a collection, i.e. if true sets attribute cardinality to ..*
isRequired - boolean.
Whether the attribute is required, i.e. if true sets attribute cardinality to 1..
refers - Reference(Entity).
Only for type=Reference. Specifies to which resourceTypes this reference can refer to
extensionUrl - string.
URL which will be used to create extension element in FHIR format. If omitted, Attribute won't be transformed in FHIR format
Use your extension
Now, you can create the ServiceRequest resource using the new attribute requestedOrganizationDepartment in the root of the resource:
Create resource in the Aidbox format:
PUT /ServiceRequest/servicerequest-with-aidbox-native-extensions
​
requestedOrganizationDepartment:
  resourceType: Organization
  display: City Hospital Neurology Department
  identifier: {system: 'urn:oid:1.2.3.4.5.6.7.8', value: '456'}
category:
- coding:
  - {code: '183829003', 
    system: 'http://snomed.info/sct', 
    display: "Refer for imaging"}
authoredOn: '2020-01-18T15:08:00'
resourceType: ServiceRequest
requester:
  resourceType: PractitionerRole
  display: Din Morgan
  identifier: {value: "1760", system: 'urn:oid:1.2.3.4.5.6.7.6'}
priority: routine
status: active
intent: original-order
performer:
- resourceType: Organization
  display: Aga Khan University Hospital Laboratory
  identifier: {value: "1514", system: 'urn:oid:1.2.3.4.5.6.7.8'}
subject:
  resourceType: Patient
  display: Jack Black, 10.12.1941
  identifier: {value: '2155800871000065', system: 'urn:oid:1.2.3.4.5.6.7.9'}
FHIR Format
You can get the resource in the FHIR format where our new attribute is rendered as the extension element:
Note that the URL is different:GET /fhir/ServiceRequest/
Request
Response
Get the resource in the FHIR format:
GET /fhir/ServiceRequest/servicerequest-with-aidbox-native-extensions
extension:
- url: urn:extension:requestedOrganizationDepartment
  valueReference:
    type: Organization
    identifier: {value: '456', system: 'urn:oid:1.2.3.4.5.6.7.8'}
    display: City Hospital Neurology Department
category:
- coding:
  - {code: '183829003', 
    system: 'http://snomed.info/sct', 
    display: "Refer for imaging"}
meta:
  lastUpdated: '2020-02-04T09:15:18.664293Z'
  versionId: '32'
  extension:
  - {url: 'ex:createdAt', valueInstant: '2020-02-04T09:12:20.103301Z'}
authoredOn: '2020-01-18T15:08:00'
resourceType: ServiceRequest
requester:
  type: PractitionerRole
  identifier: {value: '1760', system: 'urn:oid:1.2.3.4.5.6.7.6'}
  display: Din Morgan
priority: routine
status: active
id: servicerequest-with-aidbox-native-extensions
intent: original-order
subject:
  type: Patient
  identifier: {value: '2155800871000065', 
              system: 'urn:oid:1.2.3.4.5.6.7.9'}
  display: Jack Black, 10.12.1941
performer:
- type: Organization
  identifier: {value: '1514', system: 'urn:oid:1.2.3.4.5.6.7.8'}
  display: Aga Khan University Hospital Laboratory
Other extension examples
Let's create an extension of type Reference and list allowed resource types (Organization in that case) in the refers property.
managingOrganization
PUT /Attribute/ServiceRequest.managingOrganization
​
resourceType: Attribute
description: Organization that made the service request
resource: {id: ServiceRequest, resourceType: Entity}
path: [managingOrganization]
id: ServiceRequest.managingOrganization
type: {id: Reference, resourceType: Entity}
refers: 
  - Organization
extensionUrl: urn:extension:requestedOrganization
Extension of type Coding:
paymentType
PUT /Attribute/ServiceRequest.paymentType
​
resourceType: Attribute
description: Payment type for the service request, e.g. government health insurance
id: ServiceRequest.paymentType
resource:
  id: ServiceRequest
  resourceType: Entity
path:
- paymentType
type:
  id: Coding
  resourceType: Entity
extensionUrl: urn:extension:paymentType
Create resource using these extensions:
PUT /ServiceRequest/servicerequest-with-aidbox-native-extensions
​
managingOrganization:
  resourceType: Organization
  display: City Hospital
  identifier: {value: "123", system: 'urn:oid:1.2.3.4.5.6.7.8'}
requestedOrganizationDepartment:
  resourceType: Organization
  display: City Hospital Neurology Department
  identifier: {system: 'urn:oid:1.2.3.4.5.6.7.8', value: '456'}
paymentType: {system: 'urn:CodeSystem:paymentType', 
              code: "1", 
              display: "Government Health Insurance"}
resourceType: ServiceRequest
status: active
intent: original-order
subject:
  resourceType: Patient
  display: Jack Black, 10.12.1941
  identifier: {value: '2155800871000065', system: 'urn:oid:1.2.3.4.5.6.7.9'}
Request
Response
Get resource in the FHIR format:
GET /fhir/ServiceRequest/servicerequest-with-aidbox-native-extensions
resourceType: ServiceRequest
extension:
- url: urn:extension:requestedOrganization
  valueReference:
    type: Organization
    identifier: {value: '123', system: 'urn:oid:1.2.3.4.5.6.7.8'}
    display: City Hospital
- url: urn:extension:requestedOrganizationDepartment
  valueReference:
    type: Organization
    identifier: {value: '456', system: 'urn:oid:1.2.3.4.5.6.7.8'}
    display: City Hospital Neurology Department
- url: urn:extension:paymentType
  valueCoding: {code: '1', 
                system: 'urn:CodeSystem:paymentType', 
                display: Government Health Insurance}
status: active
id: servicerequest-with-aidbox-native-extensions
intent: original-order
subject:
  type: Patient
  identifier: {value: '2155800871000065', system: 'urn:oid:1.2.3.4.5.6.7.9'}
  display: Jack Black, 10.12.1941
Nested extensions
Let's create a structure of nested attributes:
performerInfo
PUT /Attribute/ServiceRequest.performerInfo
​
resourceType: Attribute
description: Information filled in by performer
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo]
id: ServiceRequest.performerInfo
extensionUrl: urn:extension:performerInfo
performerInfo.performedBy
PUT /Attribute/ServiceRequest.performerInfo.performedBy
​
resourceType: Attribute
description: 'Information filled in by performer: performed by ["Practitioner" "PractitionerRole" "Organization" "CareTeam" "HealthcareService" "Patient" "Device" "RelatedPerson"]'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, performedBy]
id: ServiceRequest.performerInfo.performedBy
type: {id: Reference, resourceType: Entity}
isCollection: true
refers: 
  - Practitioner
  - PractitionerRole
  - Organization
  - CareTeam
  - HealthcareService
  - Patient
  - Device
  - RelatedPerson
extensionUrl: urn:extension:performerInfo.performedBy
performerInfo.actualLocationReference
PUT /Attribute/ServiceRequest.performerInfo.actualLocationReference
​
resourceType: Attribute
description: 'Information filled in by performer: actual location reference'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, actualLocationReference]
id: ServiceRequest.performerInfo.actualLocationReference
type: {id: Reference, resourceType: Entity}
isCollection: true
refers: 
  - Location
extensionUrl: urn:extension:performerInfo.actualLocationReference
performerInfo.requestStatus
PUT /Attribute/ServiceRequest.performerInfo.requestStatus
​
resourceType: Attribute
description: 'Information filled in by performer: request status'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, requestStatus]
id: ServiceRequest.performerInfo.requestStatus
type: {id: code, resourceType: Entity}
enum:
  - draft
  - new
  - in-progress
  - suspended
  - expanded
  - completed
  - archive
  - cancelled
extensionUrl: urn:extension:performerInfo.requestStatus
performerInfo.requestActionHistory
PUT /Attribute/ServiceRequest.performerInfo.requestActionHistory
​
resourceType: Attribute
description: 'Information filled in by performer: request action history'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, requestActionHistory]
id: ServiceRequest.performerInfo.requestActionHistory
isCollection: true
extensionUrl: urn:extension:performerInfo.requestActionHistory
performerInfo.requestActionHistory.action
PUT /Attribute/ServiceRequest.performerInfo.requestActionHistory.action
​
resourceType: Attribute
description: 'Information filled in by performer: request action history - action'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, requestActionHistory, action]
id: ServiceRequest.performerInfo.requestActionHistory.action
type: {id: string, resourceType: Entity}
extensionUrl: urn:extension:performerInfo.requestActionHistory.action
performerInfo.requestActionHistory.date
PUT /Attribute/ServiceRequest.performerInfo.requestActionHistory.date
​
resourceType: Attribute
description: 'Information filled in by performer: request action history - date'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, requestActionHistory, date]
id: ServiceRequest.performerInfo.requestActionHistory.date
type: {id: dateTime, resourceType: Entity}
extensionUrl: urn:extension:performerInfo.requestActionHistory.date
performerInfo.requestActionHistory.subject
PUT /Attribute/ServiceRequest.performerInfo.requestActionHistory.subject
​
resourceType: Attribute
description: 'Information filled in by performer: request action history - subject'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, requestActionHistory, subject]
id: ServiceRequest.performerInfo.requestActionHistory.subject
type: {id: Reference, resourceType: Entity}
extensionUrl: urn:extension:performerInfo.requestActionHistory.subject
performerInfo.requestActionHistory.note
PUT /Attribute/ServiceRequest.performerInfo.requestActionHistory.note
​
resourceType: Attribute
description: 'Information filled in by performer: request action history - note'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, requestActionHistory, note]
id: ServiceRequest.performerInfo.requestActionHistory.note
type: {id: string, resourceType: Entity}
extensionUrl: urn:extension:performerInfo.requestActionHistory.note
performerInfo.requestActionHistory.author
PUT /Attribute/ServiceRequest.performerInfo.requestActionHistory.author
​
resourceType: Attribute
description: 'Information filled in by performer: request action history - author'
resource: {id: ServiceRequest, resourceType: Entity}
path: [performerInfo, requestActionHistory, author]
id: ServiceRequest.performerInfo.requestActionHistory.author
type: {id: Reference, resourceType: Entity}
extensionUrl: urn:extension:performerInfo.requestActionHistory.author
Let's add a resource using created extensions:
Create resource in the Aidbox format:
PUT /ServiceRequest/servicerequest-with-aidbox-native-extensions
​
resourceType: ServiceRequest
performerInfo:
  performedBy:
  - resourceType: Organization
    display: City Hospital
  - resourceType: PractitionerRole
    display: Mark Sloan
  requestStatus: completed
  requestActionHistory:
  - date: '2020-01-14T12:15:22'
    action: new
    author: {display: Meredith Grey (Psychiatrist-narcologist), resourceType: PractitionerRole}
  - date: '2020-01-14T12:15:36'
    action: in-progress
    author: {display: Derek Shepherd (General practitioner), resourceType: PractitionerRole}
  - date: '2020-01-14T12:19:00'
    action: in-progress
    author: {display: Derek Shepherd (General practitioner), resourceType: PractitionerRole}
    subject: {display: Mark Sloan (Dental surgeon), resourceType: PractitionerRole}
    note: Referred to Dr. Mark Sloan (Dental surgeon)
  - date: '2020-01-14T15:05:20'
    action: meeting
    author: {display: Mark Sloan (Dental surgeon), resourceType: PractitionerRole}
  - date: '2020-01-14T15:22:46'
    action: completed
    author: {display: Mark Sloan (Dental surgeon), resourceType: PractitionerRole}    
status: completed
intent: original-order
category:
- text: Telemedicine consultation referral
  coding:
  - {code: "TMC", system: 'urn:CodeSystem:servicerequest-category', display: "Telemedicine consultation"}
subject:
  resourceType: Patient
  display: Jack Black, 10.12.1941
  identifier: {value: '2155800871000065', system: 'urn:oid:1.2.3.4.5.6.7.9'}
Request
Response
Get resource in the FHIR format:
GET /fhir/ServiceRequest/servicerequest-with-aidbox-native-extensions
resourceType: ServiceRequest
extension:
- url: urn:extension:performerInfo
  extension:
  - url: urn:extension:performerInfo.performedBy
    valueReference: {display: City Hospital}
  - url: urn:extension:performerInfo.performedBy
    valueReference: {display: Mark Sloan}
  - {url: 'urn:extension:performerInfo.requestStatus', valueCode: completed}
  - url: urn:extension:performerInfo.requestActionHistory
    extension:
    - {url: 'urn:extension:performerInfo.requestActionHistory.date', valueDateTime: '2020-01-14T12:15:22'}
    - {url: 'urn:extension:performerInfo.requestActionHistory.action', valueString: new}
    - url: urn:extension:performerInfo.requestActionHistory.author
      valueReference: {display: Meredith Grey (Psychiatrist-narcologist)}
  - url: urn:extension:performerInfo.requestActionHistory
    extension:
    - {url: 'urn:extension:performerInfo.requestActionHistory.date', valueDateTime: '2020-01-14T12:15:36'}
    - {url: 'urn:extension:performerInfo.requestActionHistory.action', valueString: in-progress}
    - url: urn:extension:performerInfo.requestActionHistory.author
      valueReference: {display: Derek Shepherd (General practitioner)}
  - url: urn:extension:performerInfo.requestActionHistory
    extension:
    - {url: 'urn:extension:performerInfo.requestActionHistory.date', valueDateTime: '2020-01-14T12:19:00'}
    - {url: 'urn:extension:performerInfo.requestActionHistory.note', valueString: Referred to Dr. Mark Sloan (Dental surgeon)}
    - {url: 'urn:extension:performerInfo.requestActionHistory.action', valueString: in-progress}
    - url: urn:extension:performerInfo.requestActionHistory.author
      valueReference: {display: Derek Shepherd (General practitioner)}
    - url: urn:extension:performerInfo.requestActionHistory.subject
      valueReference: {display: Mark Sloan (Dental surgeon)}
  - url: urn:extension:performerInfo.requestActionHistory
    extension:
    - {url: 'urn:extension:performerInfo.requestActionHistory.date', valueDateTime: '2020-01-14T15:05:20'}
    - {url: 'urn:extension:performerInfo.requestActionHistory.action', valueString: meeting}
    - url: urn:extension:performerInfo.requestActionHistory.author
      valueReference: {display: Mark Sloan (Dental surgeon)}
    - url: urn:extension:performerInfo.requestActionHistory.subject
      valueReference: {display: '2020-01-08'}
  - url: urn:extension:performerInfo.requestActionHistory
    extension:
    - {url: 'urn:extension:performerInfo.requestActionHistory.date', valueDateTime: '2020-01-14T15:22:46'}
    - {url: 'urn:extension:performerInfo.requestActionHistory.action', valueString: completed}
    - url: urn:extension:performerInfo.requestActionHistory.author
      valueReference: {display: Mark Sloan (Dental surgeon)}
status: completed
id: servicerequest-with-aidbox-native-extensions
intent: original-order
category:
- text: Telemedicine consultation referral
  coding:
  - {code: TMC, system: 'urn:CodeSystem:servicerequest-category', display: Telemedicine consultation}
subject:
  identifier: {value: '2155800871000065', system: 'urn:oid:1.2.3.4.5.6.7.9'}
  display: Jack Black, 10.12.1941
Using FHIR extensions
FHIR extensions defined in the specification can be found in the registry http://hl7.org/fhir/extensibility-registry.html.
Let's create an attribute for the servicerequest-precondition extension:
PUT /Attribute/ServiceRequest.precondition
​
resourceType: Attribute
description: "The condition or state of the patient, prior or during 
the diagnostic procedure or test, for example, fasting, at-rest, 
or post-operative. This captures circumstances that may influence 
the measured value and have bearing on the interpretation of the result."
resource: {id: ServiceRequest, resourceType: Entity}
path: [precondition]
id: ServiceRequest.precondition
type: {id: CodeableConcept, resourceType: Entity}
isCollection: true
extensionUrl: "http://hl7.org/fhir/StructureDefinition/servicerequest-precondition"
Let's create a resource in the FHIR format:
Create resource in the FHIR format:
PUT /fhir/ServiceRequest/servicerequest-with-aidbox-native-extensions
​
resourceType: ServiceRequest
status: active
intent: original-order
subject:
  type: Patient
  display: Jack Black, 10.12.1941
extension:
  - url: http://hl7.org/fhir/StructureDefinition/servicerequest-precondition
    valueCodeableConcept:
      text: After calorie fasting
      coding:
        - code: "726055006"
          system: http://snomed.info/sct
          display: After calorie fasting
  - url: http://hl7.org/fhir/StructureDefinition/servicerequest-precondition
    valueCodeableConcept:
      text: At rest
      coding:
        - code: "263678003"
          system: http://snomed.info/sct
          display: At rest          
Let's get the resource in the Aidbox format:
Request
Response
Get resource in the Aidbox format:
GET /ServiceRequest/servicerequest-with-aidbox-native-extensions
resourceType: ServiceRequest
id: servicerequest-with-aidbox-native-extensions
intent: original-order
status: active
subject: {type: Patient, display: 'Jack Black, 10.12.1941'}
precondition:
- text: After calorie fasting
  coding:
  - {code: '726055006', 
    system: 'http://snomed.info/sct', 
    display: After calorie fasting}
- text: At rest
  coding:
  - {code: '263678003', 
    system: 'http://snomed.info/sct', 
    display: At rest}
Request headers
If you are using some HTTP-client like Postman, you will need to specify some headers.
Header
Value
Authorization
Bearer <your value>
Content-Type
text/yaml
SQL endpoints
Next - Modules
Aidbox Forms
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On this page
First-class extension as Zen profile
Define new extension
Use your extension
FHIR Format
Other extension examples
Nested extensions
Using FHIR extensions
Request headers