Fix #18: emit parse_path in function-call form for lambda params

src/ddb-sql-builder.js

@@ -173,13 +173,21 @@ export function astToSql(node, inLambda, inputType={}) {
 
 				//non-standard
 				case '_splitPath':
+					// Use the function-call form `parse_path(el, '/')` rather than the
+					// method-call form `el.parse_path('/')` when operating on a lambda
+					// parameter. DuckDB 1.4.x's binder fails to resolve a lambda parameter
+					// used as a method-call receiver inside a list_filter predicate that is
+					// itself nested in another lambda (e.g. getReferenceKey() inside a
+					// forEach) — see issue #18. The function-call form binds correctly on
+					// both 1.4.x and 1.5.x. The non-lambda case stays method-chained so
+					// flattenSql can join it onto the preceding navigation segment.
 					return inputType && inputType.isArray
 						? {
-							sql: `list_transform(el -> el.parse_path('/')[${firstArg.value}])`,
+							sql: `list_transform(el -> parse_path(el, '/')[${firstArg.value}])`,
 							outputType: {isArray: true, fhirType: "string"}
 						}
 						: {
-							sql: `${inLambda ? "el." : ""}parse_path('/')[${firstArg.value}]`, 
+							sql: `parse_path(${inLambda ? "el, " : ""}'/')[${firstArg.value}]`,
 							outputType: {isArray: false, fhirType: "string"}
 						}
 

tests/e2e.test.js

@@ -8,6 +8,7 @@ import fhirSchema from "../schemas/fhir-schema-r4.json";
 
 let db;
 let resourceFile;
+let encounterFile;
 
 const resource = {
 	"resourceType": "QuestionnaireResponse",
@@ -19,18 +20,28 @@ const resource = {
 	}]
 };
 
-beforeAll(done => {
+// Encounter with a participant referencing a Practitioner — drives the issue #18
+// test (a getReferenceKey() column inside a forEachOrNull).
+const encounterResource = {
+	resourceType: "Encounter",
+	id: "enc1",
+	status: "finished",
+	participant: [{individual: {reference: "Practitioner/prac1"}}]
+};
+
+beforeAll(async () => {
 	db = openMemoryDb();
-	// Create temporary resource file
+	// Create temporary resource files
 	resourceFile = path.join(import.meta.dir, "e2e-test-resources.temp.json");
-	Bun.write(resourceFile, JSON.stringify([resource]));
-	done();
+	encounterFile = path.join(import.meta.dir, "e2e-encounter.temp.json");
+	await Bun.write(resourceFile, JSON.stringify([resource]));
+	await Bun.write(encounterFile, JSON.stringify([encounterResource]));
 });
 
 afterAll(done => {
-	// Clean up temporary file
-	if (fs.existsSync(resourceFile)) {
-		fs.unlinkSync(resourceFile);
+	// Clean up temporary files
+	for (const file of [resourceFile, encounterFile]) {
+		if (file && fs.existsSync(file)) fs.unlinkSync(file);
 	}
 	db.close(() => done());
 });
@@ -55,7 +66,68 @@ describe("e2e tests", () => {
 			true, true
 		);
 
-		const result = await executeQuery(db, querySql);	
+		const result = await executeQuery(db, querySql);
+		expect(new Set(result)).toEqual(new Set(expected));
+	});
+
+	test("forEachOrNull with getReferenceKey() column binds on DuckDB 1.4.x (issue #18)", async () => {
+		// getReferenceKey() lowers to a where() predicate whose _splitPath step uses the
+		// lambda parameter as a method-call receiver (el.parse_path(...)). When that
+		// predicate sits in a list_filter nested inside the forEachOrNull's
+		// list_transform, DuckDB 1.4.x's binder fails to resolve the parameter:
+		//   Binder Error: Referenced column "el" not found in FROM clause!
+		// Emitting parse_path in function-call form binds correctly on 1.4.x and 1.5.x.
+		const viewDefinition = {
+			"resource": "Encounter",
+			"select": [
+				{"column": [{"name": "id", "path": "getResourceKey()"}]},
+				{
+					"forEachOrNull": "participant",
+					"column": [{
+						"name": "practitioner_id",
+						"path": "individual.getReferenceKey(Practitioner)"
+					}]
+				}
+			]
+		};
+
+		const expected = [{"id": "enc1", "practitioner_id": "prac1"}];
+		const querySql = templateToQuery(
+			viewDefinition, fhirSchema,
+			testQueryTemplate, [["test_file_path", encounterFile]],
+			true, true
+		);
+
+		const result = await executeQuery(db, querySql);
 		expect(new Set(result)).toEqual(new Set(expected));
 	});
-});
+
+	test("forEach with getReferenceKey() column binds on DuckDB 1.4.x (issue #18)", async () => {
+		// Same nested-lambda codegen as the forEachOrNull case above; forEach only
+		// differs by omitting the .ifnull2([NULL]) null-row suffix. Guards both
+		// directives against regression of the parse_path binding fix.
+		const viewDefinition = {
+			"resource": "Encounter",
+			"select": [
+				{"column": [{"name": "id", "path": "getResourceKey()"}]},
+				{
+					"forEach": "participant",
+					"column": [{
+						"name": "practitioner_id",
+						"path": "individual.getReferenceKey(Practitioner)"
+					}]
+				}
+			]
+		};
+
+		const expected = [{"id": "enc1", "practitioner_id": "prac1"}];
+		const querySql = templateToQuery(
+			viewDefinition, fhirSchema,
+			testQueryTemplate, [["test_file_path", encounterFile]],
+			true, true
+		);
+
+		const result = await executeQuery(db, querySql);
+		expect(new Set(result)).toEqual(new Set(expected));
+	});
+});