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Version: 8.1.0

FHIRPath

Pathling leverages the FHIRPath language in order to abstract away some of the complexity of navigating and interacting with FHIR data structures.

Pathling implements the minimal FHIRPath subset within the Sharable View Definition profile of the SQL on FHIR view definition.

Functions​

The following functions have been implemented in Pathling in addition to the standard set of functions within the specification.

The notation used to describe the type signature of each function is as follows:

[input type] -> [function name]([argument name]: [argument type], ...): [return type]

designation​

collection<Coding -> designation(use: Coding, language: String) : collection<String>

When invoked on a collection of Coding elements, returns a collection of designation values from the lookup operation. This can be used to retrieve synonyms, language translations and more from the underlying terminology.

If the use parameter is specified, designation values are filtered to only those with a matching use. If the language parameter is specified, designation values are filtered to only those with a matching language. If both are specified, designation values must match both the specified use and language.

See Display, Definition and Designations in the FHIR specification for more information.

Example:

// Retrieve SNOMED CT synonyms.
Condition.code.coding.designation(http://snomed.info/sct|900000000000013009)
note

The designation function is a terminology function, which means that it requires a configured terminology service. See Configuration for details.

note

The designation function is not within the FHIRPath specification, and is currently unique to the Pathling implementation.

display​

collection<Coding> -> display(language?: String) : collection<String>

When invoked on a Coding, returns the preferred display term, according to the terminology server.

The optional language parameter can be used to specify the preferred language for the display name. It overrides the default value set in the configuration. See pathling.terminology.acceptLanguage in Terminology Configuration for details.

Example:

// With no argument
Condition.code.display()

// Prefer German language.
Condition.code.display("de")
note

The display function is a terminology function, which means that it requires a configured terminology service. See Configuration for details.

note

The display function is not within the FHIRPath specification, and is currently unique to the Pathling implementation.

memberOf​

collection<Coding|CodeableConcept> -> memberOf() : collection<Boolean>

The memberOf function can be invoked on a collection of Coding or CodeableConcept values, returning a collection of Boolean values based on whether each concept is a member of the ValueSet with the specified url.

For a CodeableConcept, the function will return true if any of the codings are members of the value set.

note

The memberOf function is a terminology function, which means that it requires a configured terminology service. See Configuration for details.

See also: Additional functions

property​

collection<Coding> -> property(code: String, type: String = 'string', language?: String) : collection<String|Integer|DateTime|Decimal|Coding>

When invoked on a Coding, returns any matching property values, using the specified name and type parameters.

The type parameter has these possible values:

  • string (default)
  • code
  • Coding
  • integer
  • boolean
  • DateTime

Both the code and the type of the property must be present within a lookup response in order for it to be returned by this function. If there are no matches, the function will return an empty collection.

The optional language parameter can be used to specify the preferred language for the returned property values. It overrides the default value set in the configuration. See pathling.terminology.acceptLanguage in Terminology Configuration for details.

See Properties in the FHIR specification for more information.

Example:

// Select the code-typed property "parent".
Condition.code.coding.property('parent', 'code')

// Select the "parent" property, preferring the German language.
Condition.code.coding.property('parent', 'code', 'de')
note

The property function is a terminology function, which means that it requires a configured terminology service. See Configuration for details.

note

The property function is not within the FHIRPath specification, and is currently unique to the Pathling implementation.

subsumes​

collection<Coding|CodeableConcept> -> subsumes(code: Coding|CodeableConcept) : collection<Boolean>

This function takes a collection of Coding or CodeableConcept elements as input, and another collection as the argument. The result is a collection with a Boolean value for each source concept, each value being true if the concept subsumes any of the concepts within the argument collection, and false otherwise.

Example:

Patient.reverseResolve(Condition.subject).code.subsumes(http://snomed.info/sct|770581008)
note

The subsumes function is a terminology function, which means that it requires a configured terminology service. See Configuration for details.

See also: Additional functions

subsumedBy​

collection<Coding|CodeableConcept> -> subsumedBy(code: Coding|CodeableConcept) : collection<Boolean>

The subsumedBy function is the inverse of the subsumes function, examining whether each input concept is subsumed by any of the argument concepts.

Example:

Patient.reverseResolve(Condition.subject).code.subsumedBy(http://snomed.info/sct|73211009)
note

The subsumedBy function is a terminology function, which means that it requires a configured terminology service. See Configuration for details.

See also: Additional functions

translate​

collection<Coding|CodeableConcept> -> translate(conceptMapUrl: String, reverse: Boolean = false, equivalence: String = 'equivalent', target?: String) : collection<Coding>

When invoked on a Coding, returns any matching concepts using the ConceptMap specified using conceptMapUrl.

The reverse parameter controls the direction to traverse the map - false results in "source to target" mappings, while true results in "target to source".

The equivalence parameter is a comma-delimited set of values from the ConceptMapEquivalence ValueSet, and is used to filter the mappings returned to only those that have an equivalence value in this list.

The target parameter identifies the value set in which a translation is sought — a scope for the translation.

Example:

Condition.code.coding.translate('https://csiro.au/fhir/ConceptMap/some-map', true, 'equivalent,wider').display
note

The translate function is a terminology function, which means that it requires a configured terminology service. See Configuration for details.

note

The translate function is not within the FHIRPath specification, and is currently unique to the Pathling implementation.

Data types​

Pathling implements the following additions in the area of data types.

Coding​

A Coding is a representation of a defined concept using a symbol from a defined code system - see Using Codes in resources for more details.

The Coding literal comprises a minimum of system and code, as well as optional version, display, userSelected components:

<system>|<code>[|<version>][|<display>[|<userSelected>]]]

Not all code systems require the use of a version to unambiguously specify a code - see Versioning Code Systems.

You can also optionally single-quote each of the components within the Coding literal, in cases where certain characters might otherwise confuse the parser.

Examples:

http://snomed.info/sct|52101004
http://snomed.info/sct|52101004||Present
http://terminology.hl7.org/CodeSystem/condition-category|problem-list-item|4.0.1|'Problem List Item'
http://snomed.info/sct|'397956004 |Prosthetic arthroplasty of the hip|: 363704007 |Procedure site| = ( 24136001 |Hip joint structure|: 272741003 |Laterality| =  7771000 |Left| )'
note

The Coding literal is not within the FHIRPath specification, and is currently unique to the Pathling implementation.