Quality Control: Validating FHIR Projects

This specification describes how to write (and read) rules for the Simplifier Quality Control Engine.

Simplifier.net Quality Control progress bar

Example of Quality Control being executed on a project

Simplifier.net and Firely Terminal come with a Quality Control engine, helping you to improve the quality of your FHIR projects. The QC engine performs a series of rule checks on selected files in your Simplifier.net projects, on your local computer or at every change of your source code repository.

There are two default rulesets available, which run FHIR validation on all FHIR resources and a set of rules we at Firely recommend. Additionally, you can define any number of custom business rules to enforce your own custom profiling standards.

The results of running a ruleset

The results of running a ruleset in a Simplifier.net project

Structure

A yaml rules file is named as follows: <name>.rules.yaml. The default ruleset is called default.rules.yaml

Rulesets

A yaml ruleset file consists of entries, start with a dash, followed by a series of indented key-value pairs: Notice that the comments here are not part of the entry, just an description how to read it.

# comment for first entry

- first: value
  second: value
  third: value

# comment for second entry

- first: value
  second: value
  third: value
Simplifier.net project drop-down for running rulesets

Executing a ruleset in Simplifier.net

Default rulesets

Simplifier will provide a few default rulesets, accessible to every project: minimal.rules.yaml and recommended.rules.yaml.

Minimal ruleset

The minimal series a very small set of rules that we know everyone aggrees on. This minimal series include the bulk validation rule, validating all resources against the FHIR specification and your profiles.

Additionally it validates whether all your canonical URLs are unique, another minimal requirement for a FHIR specification.

Warning

The rules below are a snapshot in time of the QC minimal rules and are subject to change.

# This is the minimal rule series

- action: parse
  name: parse-fhir-resources
  status: "Checking if all FHIR Resource files can be parsed"
  files:
    - /**/*.xml
    - /**/*.json
    - "!package.json"

- name: resource-validation
  status: "Validating resources against the FHIR standard and their profiles"
  action: validate
  category: Resource
  suppress:
    - 6005
    - eld-16

- action: unique
  name: unique-canonicals
  status: "Checking if all StructureDefinitions have a unique canonical"
  filter: StructureDefinition
  unique: url

Minimal ruleset snapshot 05-2021

Custom rulesets

You can add other rule files to your project, as long as their name follows this pattern: <name>.rules.yaml and they are placed in the root of your project. They will all be discovered by the system, and exposed in the Quality Control menu of your project, to allow you to run them.

You can find our full syntax documentation on Simplifier.

Examples

Here are some example rules, that you might consider when writing your own rules:

Validating resources in a single folder

This example validates all resources in a single folder. It also suppresses all parsing errors

- action: validate
  files: /examples/*.xml
  suppress: https://simplifier.net/qc/errors/evaluation|PARSING

Checking canonical base URLs

This example validates whether the canonicals for your conformance resources start with the right base URL:

- name: canonical-starts-with
  filter: url.exists() and ImplementationGuide.exists().not()
  # Excluding IGs for now, since they have a Simplifier.net canonical
  status: "Checking if canonical URL starts with correct base"
  predicate: url.startsWith('https://fhir.hl7.org.uk/')
  error-message: "Canonical URL doesn't start with correct base"

Checking if Publisher and Contact are filled (correctly)

Quality Control is a powerfull way to check for consistent metadata on all of your resources. In this case we are validating if the values of publisher and contact are filled correctly and whether they match each other.

- name: publisher-filled
  filter: (StructureDefinition or ValueSet or CodeSystem or CapabilityStatement or SearchParameter or NamingSystem or ConceptMap).exists()
  # Excluding IGs for now, since they don't have a way to set metadata
  status: "Checking if all resources have publisher filled"
  predicate: publisher.exists() and (publisher in ('HL7 UK' | 'NHS Digital'))
  error-message: "Publisher not filled (correctly)"

- name: contact-filled
  filter: (StructureDefinition or ValueSet or CodeSystem or CapabilityStatement or SearchParameter or NamingSystem or ConceptMap).exists()
  # Excluding IGs for now, since they don't have a way to set metadata
  status: "Checking if all resources have contact filled"
  predicate: contact.name.exists() and ('HL7 UK' in contact.name or 'NHS Digital' in contact.name)
  error-message: "Contact not filled (correctly)"

- name: publisher-equals-contact
  filter: (StructureDefinition or ValueSet or CodeSystem or CapabilityStatement or SearchParameter or NamingSystem or ConceptMap).exists()
  # Excluding IGs for now, since they don't have a way to set metadata
  status: "Checking if publisher is one of the contacts"
  predicate: iif(publisher.exists() and contact.name.exists(), publisher in contact.name)
  error-message: "Resource has publisher not listed as one of the contacts"

Validate match between name and id

When your profiling guidelines specify conventions, you can enforce them easily with Quality Control. Like the below example, where a convention was decided upon for the name and id property of a ValueSet.

- name: valueset-id-matches-name
  filter: ValueSet.exists()
  predicate: id = name.substring(0,6) + '-' + name.substring(6)
  status: "Checking if all ValueSet ids match the names, including a dash"
  error-message: "ValueSet id must match name with a dash"

Validating correct id naming for Extensions

With Quality Control you can easily filter to specific resources, like the below case where we are checking the id value only for Extensions.

- name: extension-starts-with
  filter: StructureDefinition.exists() and StructureDefinition.type = 'Extension'
  status: "Checking whether extension starts with Extension-UKCore"
  predicate: id.startsWith('Extension-UKCore')
  error-message: "Resource does not start with Extension-UKCore"