Structured Data Capture
3.0.0 - STU 3 International flag

Structured Data Capture, published by HL7 International - FHIR Infrastructure Work Group. This is not an authorized publication; it is the continuous build for version 3.0.0). This version is based on the current content of https://github.com/HL7/sdc/ and changes regularly. See the Directory of published versions

Extension: EnableWhenExpressionExtension - Detailed Descriptions

Page standards status: Informative

Definitions for the sdc-questionnaire-enableWhenExpression extension.

1. Extension
Definition

An expression that returns a boolean value for whether to enable the item.

Control0..1 This element is affected by the following invariants: ele-1
Comments

This is only permitted when the containing item does NOT have any enableWhen elements. If the expression involves comparisons between elements that have different precisions but are otherwise equal, FHIRPath will resolve the expression to an empty set, which will in turn evaluate to false (meaning the item won't be enabled). If this is not the desired behavior, the author should add a .allTrue() to the end of the expression, which will result in an indeterminate outcome because of precision differences being handled as 'true' and the item being enabled. Questionnaires SHOULD be designed to take into account challenges around varying precision to minimize non-deterministic situations by setting constraints around expected precision, etc. If the expression evaluates to something other than a boolean true or false, the Form Filler SHOULD still display the form, and if it does so, SHOULD treat the element as 'enabled' and display a warning to the user that the questionnaire logic was faulty and it's possible that the item shouldn't be enabled.

InvariantsDefined on this element
ele-1: All FHIR elements must have a @value or children (: hasValue() or (children().count() > id.count()))
ext-1: Must have either extensions or value[x], not both (: extension.exists() != value.exists())
2. Extension.id
Definition

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

Control0..1
Typestring
3. Extension.extension
Definition

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

Control0..*
TypeExtension
Alternate Namesextensions, user content
Comments

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

InvariantsDefined on this element
ele-1: All FHIR elements must have a @value or children (: hasValue() or (children().count() > id.count()))
ext-1: Must have either extensions or value[x], not both (: extension.exists() != value.exists())
SlicingThis element introduces a set of slices on Extension.extension. The slices are unordered and Open, and can be differentiated using the following discriminators:
  • value @ url
4. Extension.url
Definition

Source of the definition for the extension code - a logical name or a URL.

Control1..1
Typeuri
Comments

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Fixed Valuehttp://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-enableWhenExpression
5. Extension.value[x]
Definition

Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

Control0..1
TypeExpression
[x] NoteSee Choice of Data Types for further information about how to use [x]
InvariantsDefined on this element
ele-1: All FHIR elements must have a @value or children (: hasValue() or (children().count() > id.count()))
inv-1: FHIR query language not allowed. (: language!='application/x-fhir-query')