FHIR Validator

Verifies that a resource's XML or JSON syntax is well-formed and that all mandatory elements are present. This includes checking cardinality (min/max occurrences), validating data types against the base FHIR schema, and ensuring that primitive values conform to their defined regular expressions. Structure validation catches missing required fields like Patient.name or Observation.status before more complex rules are evaluated.

Executes FHIRPath expressions embedded in profiles to enforce co-occurrence rules and conditional logic. Invariants are formal statements that must evaluate to true for a resource to be valid. Examples include:

• obs-3: If Observation.value is absent, dataAbsentReason must be present
• pat-1: Patient.name or Patient.deceased must be present
• Custom profile invariants like 'if MedicationRequest.status is active, then intent must be order'

Validates that coded elements use concepts from the correct ValueSet with the required binding strength. The validator checks:

• required: The code must come from the specified ValueSet or the resource is invalid
• extensible: The code must come from the ValueSet if a suitable concept exists, otherwise a local code is allowed
• example/preferred: The code should come from the ValueSet but no enforcement occurs This ensures Observation.code uses LOINC and MedicationRequest.medication uses RxNorm where mandated.

Enforces discriminator-based rules that constrain repeated elements into distinct, named sub-groups called slices. Slicing is critical for profiles like US Core Blood Pressure, where the Observation.component array must contain exactly one systolic and one diastolic slice, each identified by a specific LOINC code. The validator checks that each slice meets its own cardinality, value constraints, and terminology bindings independently.

Asserts that a resource claiming conformance to a StructureDefinition (profile) satisfies all differential constraints layered on top of the base resource. This includes:

• Verifying that all Must Support elements are populated
• Checking that elements marked as fixed value or pattern match exactly
• Ensuring that extension URLs are recognized and their nested constraints are validated recursively
• Confirming that the meta.profile tag matches the profile being validated against

Validates a resource against the complete set of rules packaged in a FHIR Implementation Guide (IG). An IG bundles multiple profiles, extensions, ValueSets, and global invariants. The validator resolves all dependencies, loads the package manifest, and tests the resource against every applicable profile simultaneously. This is the definitive check for US Core, Da Vinci, or CARIN conformance, producing an aggregated OperationOutcome with issues, locations, and severity levels.

A constrained and extended subset of a base FHIR resource tailored to meet the specific data requirements of a particular country, domain, or implementation guide. The FHIR Validator uses profiles as the primary rulebook to check conformance.

• Defines cardinality (required/forbidden elements)
• Narrows terminology bindings to specific ValueSets
• Applies invariants (co-occurrence rules) expressed in FHIRPath

The mechanism in FHIR that links a coded element to a specific ValueSet, defining the allowed set of codes and the strength of that requirement. The validator checks if the supplied code is a member of the bound ValueSet.

• required: Must be from the defined ValueSet
• extensible: Must be from the ValueSet if a code exists, otherwise local codes allowed
• example: A hint for implementers, not enforced

A path-based navigation and extraction language used in FHIR to query and compute expressions on FHIR data. The validator executes FHIRPath invariants to enforce complex co-occurrence constraints that cannot be expressed in a simple StructureDefinition.

• Example: condition.exists() or severity.empty()
• Used for slicing discriminators
• Powers search parameter extraction logic

A FHIR resource returned by a server to provide detailed information about the success or failure of an operation. The FHIR Validator returns an OperationOutcome containing a list of issues with severity levels.

• error: A violation of a required constraint
• warning: A best practice violation
• information: A structural hint
• Each issue includes a location string pinpointing the exact path of the error

A published set of rules, profiles, and documentation that defines how FHIR must be used to solve a specific clinical or administrative interoperability problem. The validator is the gatekeeper that certifies a server or document conforms to an IG's full set of constraints.

• Bundles all profiles, extensions, and ValueSets
• Defines capability statements for server conformance
• Examples: US Core, Da Vinci PDex, IPA

A concise, text-based authoring language used to define FHIR profiles, extensions, and implementation guides, which is then compiled into formal FHIR definitions. The SUSHI compiler transforms FSH into the StructureDefinitions that the FHIR Validator consumes.

• Profile: MyPatient defines a new constrained profile
• * status 1..1 sets cardinality
• * identifier from http://example.org/vs binds a ValueSet