Module @iguhealth/fhirpath - v0.12.0
FHIRPath
API
evaluate
Returns a JS object/primitive based on the evaluation.
evaluate(
expression: string,
ctx: unknown,
options?: Options
): NonNullable<unknown>[]
evaluateWithMeta
Returns a @iguhealth/meta-value singular value which contains data along with metadata about the evaluation.
function evaluateWithMeta(
expression: string,
ctx: unknown,
options?: Options,
): MetaValueSingular<NonNullable<unknown>>[];
Arguments
| name |
type |
description |
| expression |
string |
FHIRPath expression to evaluate. |
| ctx |
unknown |
The context which the fhirpath is being evaluated from (sets $this context). |
| options |
Object |
Includes variables and metadata deriviation functions. |
| options.variables |
Object | Function |
If an object is Record<variableName, variableValue> else (variableName)=> variableValue. |
| options.meta |
Object |
MetaInformation used to zip metadata with value. Used in type functions and operators. |
| options.meta.type |
string |
Root type for ctx. |
| options.meta.getSD |
(fhir_version: FHIRVersion, type: string) => StructureDefinition |
Returns a StructureDefinition based on type passed in. |
Usage
import * as fhirpath from "@iguhealth/fhirpath";
// Default returns javascript object.
expect(fhirpath.evaluate("4 + 5", {})).toEqual([9]);
expect(fhirpath.evaluate("$this.test + 2 * 4", { test: 4 })).toEqual([12]);
// Evaluation with metavalue return (returns value in addition to meta information.)
expect(
evaluateWithMeta(
"$this.name",
{
resourceType: "Patient",
name: [{ given: ["bob"], family: "jameson" }],
},
{
meta: {
type: "Patient",
getSD: (fhirVersion, type: code) => {
const foundSD = sds.find((sd) => sd.type === type);
return foundSD;
},
},
},
).map((v) => v.meta()?.type),
).toEqual(["HumanName"]);
Operations supported
| Operation |
Description |
Supported |
| + (addition) |
Concatenate strings or add values if numeric. |
true |
| - (subtraction) |
Subtracts the right operand from the left operand. |
true |
| as type specifier |
Returns left operand if value is of type specified. |
true |
| is(type : type specifier) |
Filters left operand based on type specifier. |
true |
| * (multiplication) |
Multiplies both arguments. |
true |
| / (division) |
Divides the left operand by the right operand |
true |
| | (union collections) |
Merge the two collections into a single collection |
true |
| = (Equals) |
Returns true if the left collection is equal to the right collection |
true |
| != (Not Equals) |
Converse operator of equals returns true if left collection is not equal to right collection |
true |
Supported Functions
| Name |
Description |
Supported |
| empty |
Returns true if the input collection is empty ({ }) and false otherwise. |
true |
| exists |
Returns true if the collection has any elements, and false otherwise. |
true |
| all |
Returns true if for every element in the input collection, criteria evaluates to true. |
true |
| allTrue |
Takes a collection of Boolean values and returns true if all the items are true. |
true |
| anyTrue |
Takes a collection of Boolean values and returns true if any of the items are true. |
true |
| allFalse |
Takes a collection of Boolean values and returns true if all the items are false. |
true |
| anyFalse |
Takes a collection of Boolean values and returns true if any of the items are false. |
true |
| subsetOf |
Returns true if all items in the input collection are members of the collection passed in. |
true |
| supersetOf |
Returns true if all items in the collection passed as the other argument are members of the input collection. |
true |
| count |
Returns the integer count of the number of items in the input collection. |
true |
| distinct |
Returns a collection containing only the unique items in the input collection. |
true |
| isDistinct |
Returns true if all the items in the input collection are distinct. |
true |
| where |
Returns a collection containing only those elements in the input collection based on where expression. |
true |
| select |
Evaluates the projection expression for each item in the input collection. |
true |
| repeat |
A version of select that will repeat the projection and add it to the output collection. |
true |
| ofType |
Returns a collection that contains all items in the input collection that are of the given type. |
true |
| as |
Returns filter same as ofType used for backwards compatibility. |
true |