fhirpath-rb

FHIRPath implementation in Ruby.

This is a Ruby port of fhirpath-py, which is itself a Python port of fhirpath.js. The goal is to bring the same evaluator (parser, engine, built-in function library, and FHIR data models) to the Ruby ecosystem.

Installation

bundle add fhirpath-rb

Usage

compile_as_first and compile_as_array parse a FHIRPath expression once and return a reusable callable that accepts a fhir_models resource instance and wraps results as instances of a given output_type (raw values pass through as-is when output_type isn't a fhir_models class):

require "fhirpath"

patient = FHIR::Patient.new(
  "name" => [
    { "use" => "official", "given" => ["Peter", "James"], "family" => "Chalmers" },
    { "use" => "usual", "given" => ["Jim"] }
  ]
)

first_name = Fhirpath.compile_as_first("Patient.name.where(use = 'usual')", FHIR::Patient, FHIR::HumanName)
first_name.call(patient)
# => #<FHIR::HumanName ...>

all_given = Fhirpath.compile_as_array("Patient.name.given", FHIR::Patient, String)
all_given.call(patient)
# => ["Peter", "James", "Jim"]

Fhirpath.evaluate works directly against a plain resource Hash and returns raw values:

patient = {
  "resourceType" => "Patient",
  "name" => [
    { "use" => "official", "given" => ["Peter", "James"], "family" => "Chalmers" },
    { "use" => "usual", "given" => ["Jim"] }
  ]
}

Fhirpath.evaluate(patient, "Patient.name.where(use = 'usual').given.first()")
# => ["Jim"]

Development

After checking out the repo, run bin/setup to install dependencies. Then run rake spec to run the tests, and bundle exec rake to run the full default task (specs + rubocop). You can also run bin/console for an interactive prompt.

License

The gem is available as open source under the terms of the MIT License.