ModelResolver class abstract

The boundary between FHIR-version-specific code and the CQL engine.

Implementations of this interface are the only place in fhir_cql where package:fhir_r4 / package:fhir_r5 / package:fhir_r6 (and the matching _path packages) may be imported. The engine itself works exclusively in CQL System types (see lib/engine/types/) plus raw Map<String, dynamic> FHIR JSON — never typed FHIR classes.

This mirrors the ModelResolver interface from the canonical Java reference implementation cqframework/clinical_quality_language (Src/java/engine/src/commonMain/kotlin/org/opencds/cqf/cql/engine/model/ModelResolver.kt) and the FHIRWrapper pattern from the JavaScript reference cqframework/cql-exec-fhir.

Rules for implementers

1. Use the modern FHIRPath entry point only: FHIRPathEngine.create(WorkerContext(), hostServices).parse(expr) .evaluateWithContext(...). Never use or reference walkFhirPath / executeFhirPath — these are legacy petitparser-era shims that silently mis-handle host-services and lazy variable scenarios. See feedback_no_walkfhirpath in memory.

2. Convert FHIR-typed values to CQL System types eagerly at the boundary. Once a value flows into the engine via resolvePath or toCqlSystemType, it must be either a CQL System type, a plain Map<String, dynamic> FHIR JSON, or a primitive String/num/bool. The engine must not see fhir_r4.FhirDateTime etc.

3. Handle FHIR polymorphic field resolution (effective → effectiveDateTime / effectivePeriod / effectiveTiming / effectiveInstant, value → valueQuantity / valueString / …, onset → onsetDateTime / onsetAge / …, etc.) inside resolvePath. The set of polymorphic prefixes is documented per FHIR version in the model_info files.

Constructors

ModelResolver()

Properties

fhirVersion → String

FHIR version targeted, matching the CQL using FHIR version declaration. Examples: '4.0.1', '5.0.0', '6.0.0-ballot2'.

no setter

hashCode → int

The hash code for this object.

no setter, inherited

packageNames → List<String>

Type-system namespace URI(s) this resolver answers for. CQL type specifiers carry a namespace.namespaceURI; the engine dispatches to the resolver whose packageNames includes that URI.

no setter

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

as_(dynamic value, String typeName, {bool isStrict = false}) → dynamic

Returns value cast to typeName if compatible, otherwise:

createInstance(String typeName) → dynamic

Creates an empty instance of the type named typeName. Used by CQL's instance-construction expression ({ field1: ..., field2: ... } typed to a named type) and by the parameter system.

fromCqlSystemType(dynamic value, [String? fhirTypeName]) → dynamic

Inverse of toCqlSystemType: convert a CQL System value back to a FHIR-typed value (or FHIR JSON Map) for return to user code.

getContextPath(String? contextType, String? targetType) → String?

Returns the path on a resource of targetType that links it to a resource of contextType (the CQL context declaration's anchor).

is_(dynamic value, String typeName) → bool?

Returns true if value is an instance of the FHIR or System type named typeName in this resolver's package(s).

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

objectEqual(dynamic left, dynamic right) → bool?

Three-valued deep equality. Returns true/false when comparable; null when either operand is null and the spec demands propagation.

objectEquivalent(dynamic left, dynamic right) → bool?

CQL ~ operator on FHIR-typed values. Type-aware equivalence per the FHIR datatypes specification (e.g. Quantity ignores comparator/unit canonicalization; Period is start-exclusive/end-inclusive).

resolveId(dynamic target) → String?

Returns the resource id of target if it's a FHIR resource, else null.

resolvePath(dynamic source, String path) → Future

Resolves a single property path on a source object.

resolveType(String typeName) → Type?

Resolves typeName (in this resolver's namespace) to a Dart Type suitable for reflection / instance creation. Returns null if unknown.

resolveTypeOf(dynamic value) → String?

Returns the type name for value in this resolver's namespace, e.g. 'Patient' for a FHIR Patient resource, 'DateTime' for a CqlDateTime. Returns null if value doesn't map.

resolveTypePath(String path) → ({bool isList, String type})?

Resolves the static type of a dotted model path such as Observation.value or Patient.name, for return-type inference (used by the engine's Property.getReturnTypes).

setValue(dynamic target, String path, dynamic value) → dynamic

Sets the value at path on target to value, returning the modified target. Used by the engine for set / output-parameter scenarios.

toCqlSystemType(dynamic value) → dynamic

Converts a FHIR-typed value (or raw FHIR JSON Map) to its corresponding CQL System type at the engine boundary.

toElementMap(dynamic value) → Map<String, dynamic>?

Decomposes a model object into its child elements as a FHIR-JSON name → value map, or returns null if value is not a model object.

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited