R4 Draft for Comment

This page is part of the FHIR Specification (v3.2.0: R4 Ballot 1). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions . Page versions: R5 R4B R4 R3 R2

4.8.15 Resource ValueSet - Operations

Vocabulary Work GroupMaturity Level: 5 Normative Compartments: Not linked to any defined compartments

Normative Candidate Note: This page is candidate normative content for R4 in the Conformance Package. Once normative, it will lose it's Maturity Level, and breaking changes will no longer be made.

This resource has 2 operations associated with it:

$expandValue Set Expansion
$validate-codeValue Set based Validation

For more information about operations, including how they are invoked, see Operations.

4.8.15.1 Value Set Expansion

The definition of a value set is used to create a simple collection of codes suitable for use for data entry or validation. If the operation is not called at the instance level, one of the in parameters constraint, context or valueset must be provided. An expanded value set will be returned, or an OperationOutcome with an error message.

The official URL for this operation definition is

 http://hl7.org/fhir/OperationDefinition/ValueSet-expand

Formal Definition (as a OperationDefinition).

URL: [base]/ValueSet/$expand

URL: [base]/ValueSet/[id]/$expand

This is an idempotent operation

In Parameters:
NameCardinalityTypeBindingProfileDocumentation
url0..1uri

A canonical url for a value set. The server must know the value set (e.g. it is defined explicitly in the server's value sets, or it is defined implicitly by some code system known to the server

valueSet0..1ValueSet

The value set is provided directly as part of the request. Servers may choose not to accept value sets in this fashion

context0..1uri

The context of the value set, so that the server can resolve this to a value set to expand. The recommended format for this URI is [Structure Definition URL]#[name or path into structure definition] e.g. http://hl7.org/fhir/StructureDefinition/observation-hspc-height-hspcheight#Observation.interpretation. Other forms may be used but are not defined. This form is only usable if the terminology server also has access to the profile registry that the server is using, but can be used to delegate the mapping from an application context to a binding at run-time

filter0..1string

A text filter that is applied to restrict the codes that are returned (this is useful in a UI context). The interpretation of this is delegated to the server in order to allow to determine the most optimal search approach for the context

profile0..1uri

A reference to an external definition that provides additional control information about how the expansion is performed. At this time, there is no agreed format or functionality for the target of this URI. The VSAC Documentation provides one example of the use of this parameter. Implementers using this element will need to agree on an appropriate mechanism for use within their interoperability community. Known uses for profile include: * whether to return the value set content logical definition with the expansion * whether to include inactive concepts

date0..1dateTime

The date for which the expansion should be generated. if a date is provided, it means that the server should use the value set / code system definitions as they were on the given date, or return an error if this is not possible. Normally, the date is the current conditions (which is the default value) but under some circumstances, systems need to generate an expansion as it would have been in the past. A typical example of this would be where code selection is constrained to the set of codes that were available when the patient was treated, not when the record is being edited. Note that which date is appropriate is a matter for implementation policy.

offset0..1integer

Paging support - where to start if a subset is desired (default = 0). Offset is number of records (not number of pages)

count0..1integer

Paging support - how many codes should be provided in a partial page view. Paging only applies to flat expansions - servers ignore paging if the expansion is not flat. If count = 0, the client is asking how large the expansion is. Servers SHOULD honor this request for hierarchical expansions as well, and simply return the overall count

includeDesignations0..1boolean

Controls whether concept designations are to be included or excluded in value set expansions. Overrides the value in the expansion profile if there is one

includeDefinition0..1boolean

Controls whether the value set definition is included or excluded in value set expansions. Overrides the value in the expansion profile if there is one

activeOnly0..1boolean

Controls whether inactive concepts are included or excluded in value set expansions. Overrides the value in the expansion profile if there is one. Note that if the value set explicitly specifies that inactive codes are included, this parameter can still remove them from a specific expansion, but this parameter cannot include them if the value set excludes them

excludeNested0..1boolean

Controls whether or not the value set expansion nests codes or not (i.e. ValueSet.expansion.contains.contains). Overrides the value in the expansion profile if there is one

excludeNotForUI0..1boolean

Controls whether or not the value set expansion includes codes which cannot be displayed in user interfaces. Overrides the value in the expansion profile if there is one

excludePostCoordinated0..1boolean

Controls whether or not the value set expansion includes post coordinated codes. Overrides the value in the expansion profile if there is one

displayLanguage0..1code

Specifies the language to be used for description in the expansions i.e. the language to be used for ValueSet.expansion.contains.display. Overrides the value in the expansion profile if there is one

limitedExpansion0..1boolean

If the value set being expanded is incomplete (because it is too big to expand), return a limited expansion (a subset) with an indicator that expansion is incomplete. Overrides the value in the expansion profile if there is one

Out Parameters:
NameCardinalityTypeBindingProfileDocumentation
return1..1ValueSet

The result of the expansion

Note: as this the only out parameter, it is a resource, and it has the name 'return', the result of this operation is returned directly as a resource

The value set expansion returned by this query should be treated as a transient result that will change over time (whether it does or not depends on how the value set is specified), so applications should repeat the operation each time the value set is used.

If the expansion is too large (at the discretion of the server), the server will return an error (OperationOutcome with code too-costly). Clients can work through large flat expansions in a set of pages (partial views of the full expansion) instead of just getting the full expansion in a single exchange by using offset and count parameters. Servers are not obliged to support paging, but if they do, SHALL support both the offset and count parameters. Hierarchical expansions are not subject to paging and servers simply return the entire expansion.

Different servers may return different results from expanding a value set for the following reasons:

  • The underlying code systems are different (e.g. different versions, possibly with different defined behavior)
  • The server optimizes filter includes differently, such as sorting by code frequency
  • Servers introduce arbitrary groups to assist a user to navigate the lists based either on extensions in the definition, or additional knowledge available to the server

When a server cannot correctly expand a value set because it does not fully understand the code systems (e.g. it has the wrong version, or incomplete definitions) then it SHALL return an error. If the value set itself is unbounded due to the inclusion of post-coordinated value sets (e.g. SNOMED CT, UCUM), then the extension http://hl7.org/fhir/StructureDefinition/valueset-unclosed can be used to indicate that the expansion is incomplete

4.8.15.1.1 Examples

Expanding a value set that is already registered on the server as "23", with a text filter of "abdo" (Request):

GET [base]/ValueSet/23/$expand?filter=abdo

Expanding a value set that is specififed by the client (using JSON) (Request):

POST [base]/ValueSet/23/$expand
[other headers]

{
  "resourceType" : "Parameters",
  "parameter" : [
     {
     "name" : "valueSet",
     "resource" : {
       "resourceType" : "ValueSet",
     [value set details]
     }
   }
  ]
}

Response:

HTTP/1.1 200 OK
[other headers]

<ValueSet xmlns="http://hl7.org/fhir">
  <!-- the server SHOULD populate the id with a newly created UUID
    so clients can easily track a particular expansion  -->
  <id value="43770626-f685-4ba8-8d66-fb63e674c467"/>
  <!-- no need for meta, though it is allowed for security labels, profiles -->

  <!-- other value set details -->
  <expansion>
    <!-- when expanded -->
    <timestamp value="20141203T08:50:00+11:00"/>
  <contains>
    <!-- expansion contents -->
  </contains>
  </expansion>
</ValueSet>

 

4.8.15.2 Value Set based Validation

Validate that a coded value is in the set of codes allowed by a value set. If the operation is not called at the instance level, one of the in parameters "constraint" or "valueset" must be provided. One (and only one) of the in parameters (code, coding, codeableConcept) must be provided. The operation returns a result (true / false), an error message, and the recommended display for the code

The official URL for this operation definition is

 http://hl7.org/fhir/OperationDefinition/ValueSet-validate-code

Formal Definition (as a OperationDefinition).

URL: [base]/ValueSet/$validate-code

URL: [base]/ValueSet/[id]/$validate-code

This is an idempotent operation

In Parameters:
NameCardinalityTypeBindingProfileDocumentation
url0..1uri

Value set Canonical URL. The server must know the value set (e.g. it is defined explicitly in the server's value sets, or it is defined implicitly by some code system known to the server

context0..1uri

The context of the value set, so that the server can resolve this to a value set to validate against. The recommended format for this URI is [Structure Definition URL]#[name or path into structure definition] e.g. http://hl7.org/fhir/StructureDefinition/observation-hspc-height-hspcheight#Observation.interpretation. Other forms may be used but are not defined. This form is only usable if the terminology server also has access to the profile registry that the server is using, but can be used to delegate the mapping from an application context to a binding at run-time

valueSet0..1ValueSet

The value set is provided directly as part of the request. Servers may choose not to accept value sets in this fashion. This parameter is used when the client wants the server to expand a value set that is not stored on the server

code0..1code

The code that is to be validated. If a code is provided, a system or a context must be provided (if a context is provided, then the server SHALL ensure that the code is not ambiguous without a system)

system0..1uri

The system for the code that is to be validated

version0..1string

The version of the system, if one was provided in the source data

display0..1string

The display associated with the code, if provided. If a display is provided a code must be provided. If no display is provided, the server cannot validate the display value, but may choose to return a recommended display name in an extension in the outcome. Whether displays are case sensitive is code system dependent

coding0..1Coding

A coding to validate

codeableConcept0..1CodeableConcept

A full codeableConcept to validate. The server returns true if one of the coding values is in the value set, and may also validate that the codings are not in conflict with each other if more than one is present

date0..1dateTime

The date for which the validation should be checked. Normally, this is the current conditions (which is the default values) but under some circumstances, systems need to validate that a correct code was used at some point in the past. A typical example of this would be where code selection is constrained to the set of codes that were available when the patient was treated, not when the record is being edited. Note that which date is appropriate is a matter for implementation policy.

abstract0..1boolean

if true, then an abstract code is allowed to be used in the context of the code that is being validated. Typically, abstract codes are allowed to be used in value set specifications (e.g. any code that is subsumed by an abstract code), but not in an actual recrod. If false (which is the default value), then only concrete codes as defined by the code systemt are allowed

displayLanguage0..1code

Specifies the language to be used for description when validating the display property

Out Parameters:
NameCardinalityTypeBindingProfileDocumentation
result1..1boolean

True if the concept details supplied are valid

message0..1string

Error details, if result = false. If this is provided when result = true, the message carries hints and warnings

display0..1string

A valid display for the concept if the system wishes to display this to a user

4.8.15.2.1 Examples

Simple validation of a code/system against a known value set (Request):

GET [base]/ValueSet/23/$validate-code?system=http://loinc.org&code=1963-8&display=test

Validate a CodeableConcept against a client specified value set (Request):

POST [base]/ValueSet/$validate-code
[other headers]

{
  "ResourceType" : "Parameters",
  "parameter" : [
    {
    "name" : "coding",
    "valueCodeableConcept" : {
      "coding" : {
        "system" : "http://loinc.org",
          "code" : "1963-8",
      "display" : "test"
      }
    }
  },
  {
    "name" : "valueSet",
    "resource": {
      "resourceType" : "ValueSet",
    [etc]
    }
  }
  ]
}

Test whether a Snomed Concept 399211009 (History of myocardial infarction) is subsumed by 22298006 (Myocardial infarction) (Request):


GET [base]/ValueSet/$validate-code?system=http://snomed.info/sct&code=399211009&url=http://snomed.info/sct?fhir_vs%3Disa/22298006

Response:

HTTP/1.1 200 OK
[other headers]

{
  "resourceType" : "Parameters",
  "parameter" : [
    {
    "name" : "result",
    "valueBoolean" : "false"
  },
  {
    "name" : "message",
    "valueString" : "The display \"test\" is incorrect"
  },
  {
    "name" : "display",
    "valueString" : "Bicarbonate [Moles/volume] in Serum"
  }
  ]
}