Phase 2: Typed variables, select_identifier filter, FhirR4 template packaging

[Chethan77]

Summary

Phase 2 of the Convert Engine Variable Support spec. Extends Phase 1's string-only variables with typed variables (String, Numeric, Complex + JSON Schema validation), adds a select_identifier custom Liquid filter with coding-scoped compound matching, updates the Dragon MRN template, and packages FhirR4 templates into the default template collection.

Changes

Core Library

• Models/VariableDefinition.cs (new) — VariableType enum (String, Numeric, Complex) and VariableDefinition class
• Utilities/VariableValidator.cs — ValidateTypedVariables() with per-type validation, schema size limit (MaxVariableSchemaLength), null entry guard. Preserves all Phase 1 validation rules.
• Processors/IFhirConverter.cs — 2 new IList<VariableDefinition> overloads
• Processors/BaseProcessor.cs — Virtual stubs for typed overloads
• Processors/FhirR4Processor.cs — Typed overloads with runtime normalization: long/double for Numeric (invariant culture), JTokenExtensions.ToObject() → Hash.FromDictionary() for Complex
• Filters/IdentifierSelectionFilters.cs (new) — SelectIdentifier filter with coding-scoped compound matching
• Resources.resx / Resources.Designer.cs — 13 new resource strings

Templates & Schema

• DragonPatientMrn.liquid — Replaced manual loop matching with select_identifier: vars.selectionCriteria
• Schemas/IdentifierSelectionCriteria.json (new) — JSON Schema for selection criteria
• TypedVarTest.liquid (new) — Test template for typed variable injection verification

Template Packaging

• DefaultTemplateInfo.cs — FhirR4DefaultTemplatesResource + microsofthealth/fhirr4templates:default map entry
• DefaultTemplateCollectionProvider.cs — FhirR4 extraction task
• Microsoft.Health.Fhir.TemplateManagement.csproj — Embedded resource + prebuild tar command

Tests

• IdentifierSelectionFiltersTests.cs (new) — 14 direct filter tests including cross-coding false-positive prevention
• FhirR4ProcessorTests.cs — Typed-variable validation, injection, null entry, oversize schema tests
• FhirR4ConvertDataFunctionalTests.cs — Test cases 2a–2g + cross-coding verification
• DefaultTemplateInfoTest.cs, ImageInfoTest.cs, DefaultTemplateCollectionProviderTests.cs, TemplateCollectionProviderTests.cs — FhirR4 template collection entries

Key Design Decisions

• Coding-scoped matching: A single coding entry must satisfy ALL coding-level conditions simultaneously. Prevents false positives where type.coding.system matches coding A and type.coding.code matches coding B on the same identifier.
• Schema size limit: MaxVariableSchemaLength (1 MB) rejects oversize schemas before NJsonSchema parsing to prevent CPU/memory DoS.
• Invariant culture: Numeric parsing uses CultureInfo.InvariantCulture to prevent locale drift.
• Backward compat: Phase 1 IDictionary<string, string> overloads are unchanged.

Breaking Change

DragonPatientMrn.liquid now requires a selectionCriteria complex variable instead of matchCode + dragonSystem string variables. This is intentional for Phase 2; dual-path support deferred.

Test Results

• Unit tests: 505 passed, 0 failed
• Functional tests: 2414 passed, 0 failed

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[Copilot]

Pull request overview

Implements Phase 2 of variable support for the Liquid converter by introducing typed variables (with JSON Schema validation for complex types), adding a select_identifier Liquid filter for robust Identifier selection, and packaging FHIR R4 templates into the default template collection.

Changes:

• Add typed variable model + validation (String/Numeric/Complex with JSON Schema + size limits) and new converter overloads to accept typed variables.
• Introduce select_identifier Liquid filter and update the Dragon MRN template to use criteria-based identifier selection.
• Package FHIR R4 templates as an embedded default template bundle and update related unit/functional tests.

Reviewed changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Microsoft.Health.Fhir.TemplateManagement/Models/DefaultTemplateInfo.cs	Adds FHIR R4 default template resource and maps microsofthealth/fhirr4templates:default.
src/Microsoft.Health.Fhir.TemplateManagement/Microsoft.Health.Fhir.TemplateManagement.csproj	Embeds + builds FhirR4DefaultTemplates.tar.gz from data/Templates/FhirR4.
src/Microsoft.Health.Fhir.TemplateManagement/ArtifactProviders/DefaultTemplateCollectionProvider.cs	Extracts FHIR R4 default templates alongside other default bundles.
src/Microsoft.Health.Fhir.TemplateManagement.UnitTests/Providers/TemplateCollectionProviderTests.cs	Adds cache + expectations for the new FHIR R4 default template layer.
src/Microsoft.Health.Fhir.TemplateManagement.UnitTests/Providers/DefaultTemplateCollectionProviderTests.cs	Adds DefaultRootTemplateParentPath.FhirR4 mapping coverage.
src/Microsoft.Health.Fhir.TemplateManagement.UnitTests/Models/ImageInfoTest.cs	Adds microsofthealth/fhirr4templates:default to supported references (case-sensitive + insensitive).
src/Microsoft.Health.Fhir.TemplateManagement.UnitTests/Models/DefaultTemplateInfoTest.cs	Validates new DefaultTemplateInfo entry for FHIR R4 templates.
src/Microsoft.Health.Fhir.Liquid.Converter/Utilities/VariableValidator.cs	Adds typed-variable validation, schema size limit, and JSON Schema validation for complex variables.
src/Microsoft.Health.Fhir.Liquid.Converter/Resources.resx	Adds resource strings for typed-variable and identifier-selection errors.
src/Microsoft.Health.Fhir.Liquid.Converter/Resources.Designer.cs	Auto-generated accessors for the newly added resource strings.
src/Microsoft.Health.Fhir.Liquid.Converter/Processors/IFhirConverter.cs	Adds typed-variable Convert overloads.
src/Microsoft.Health.Fhir.Liquid.Converter/Processors/FhirR4Processor.cs	Implements typed-variable conversion path and runtime normalization (numeric + complex).
src/Microsoft.Health.Fhir.Liquid.Converter/Processors/BaseProcessor.cs	Adds virtual typed-variable overload stubs for processors that don’t support typed variables.
src/Microsoft.Health.Fhir.Liquid.Converter/Models/VariableDefinition.cs	Introduces VariableDefinition + VariableType (String/Numeric/Complex).
src/Microsoft.Health.Fhir.Liquid.Converter/Filters/IdentifierSelectionFilters.cs	Adds select_identifier filter with coding-scoped compound matching.
src/Microsoft.Health.Fhir.Liquid.Converter.UnitTests/Processors/FhirR4ProcessorTests.cs	Updates existing tests to typed variables and adds extensive Phase 2 validation/injection coverage.
src/Microsoft.Health.Fhir.Liquid.Converter.UnitTests/Filters/IdentifierSelectionFiltersTests.cs	Adds direct unit tests for select_identifier, including cross-coding false-positive prevention.
src/Microsoft.Health.Fhir.Liquid.Converter.FunctionalTests/FhirR4ConvertDataFunctionalTests.cs	Adds functional scenarios for typed criteria + filter behavior.
data/Templates/FhirR4/TypedVarTest.liquid	Adds template to verify numeric vs string rendering behavior.
data/Templates/FhirR4/Schemas/IdentifierSelectionCriteria.json	Adds JSON Schema for selectionCriteria variable validation.
data/Templates/FhirR4/DragonPatientMrn.liquid	Switches MRN selection from manual loops to select_identifier + selectionCriteria.

Files not reviewed (1)

• src/Microsoft.Health.Fhir.Liquid.Converter/Resources.Designer.cs: Language not supported

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[Copilot]

Numeric validation currently accepts values like NaN, Infinity, and -Infinity because double.TryParse returns true for them under invariant culture. Those tokens are not valid JSON numbers and will later fail JSON parsing in post-processing. Tighten validation to reject non-finite doubles (e.g., check double.IsNaN/double.IsInfinity after parsing).

Suggested change

	if (!long.TryParse(variable.Value, NumberStyles.Integer, CultureInfo.InvariantCulture, out _) &&
	!double.TryParse(variable.Value, NumberStyles.Float | NumberStyles.AllowThousands, CultureInfo.InvariantCulture, out _))
	var isValidInteger = long.TryParse(variable.Value, NumberStyles.Integer, CultureInfo.InvariantCulture, out _);
	var isValidFiniteDouble = double.TryParse(variable.Value, NumberStyles.Float | NumberStyles.AllowThousands, CultureInfo.InvariantCulture, out double parsedDouble) &&
	!double.IsNaN(parsedDouble) &&
	!double.IsInfinity(parsedDouble);
	if (!isValidInteger && !isValidFiniteDouble)

[Copilot]

valueToken is parsed from variable.Value but never used afterward, and schema.Validate(variable.Value) will parse the JSON again internally. Either remove the redundant JToken.Parse step, or use the parsed token for schema validation (to avoid double parsing) so this code stays warning-free and more efficient.

Suggested change

	var errors = schema.Validate(variable.Value);
	var errors = schema.Validate(valueToken);

[Copilot]

templates is a plain List<Dictionary<string, Template>> that is being mutated (templates.Add(...)) concurrently from multiple Task.Run calls. List<T> is not thread-safe, so this can lead to race conditions (corruption, missed entries, or runtime exceptions). Consider having each task return its extracted dictionary (e.g., Task<Dictionary<string, Template>>) and combine results after WhenAll, or use a thread-safe collection/lock around Add.