#3466 fix and improve openapi generation (#4436)

* Update fhir version constants from 4.0.0 to 4.0.1

Yes, this means the test fails.  The root cause of the failure is possibly the incorrect fhir version
in org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/model/Constants.java

* fixes hapifhir/hapi-fhir#3466

Includes a POST version for every GET endpoint.
Excludes non-primitive parameters from GET endpoints.
For an idempotent (affectsState=false) endpoint with at least one required non-primitive parameter, only support POST

Also include */_search endpoints for the Search operation.

hapi-fhir-server-openapi/src/main/java/ca/uhn/fhir/rest/openapi/OpenApiInterceptor.java

@@ -77,6 +77,9 @@ import org.hl7.fhir.r4.model.Reference;
 import org.hl7.fhir.r4.model.Resource;
 import org.hl7.fhir.r4.model.StringType;
 import org.hl7.fhir.r4.model.Type;
+import org.hl7.fhir.r4.model.OperationDefinition.OperationDefinitionParameterComponent;
+import org.hl7.fhir.r4.model.OperationDefinition.OperationParameterUse;
+import org.hl7.fhir.r4.model.codesystems.DataTypes;
 import org.thymeleaf.IEngineConfiguration;
 import org.thymeleaf.TemplateEngine;
 import org.thymeleaf.cache.AlwaysValidCacheEntryValidity;
@@ -98,6 +101,7 @@ import java.io.InputStream;
 import java.math.BigDecimal;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
@@ -569,21 +573,8 @@ public class OpenApiInterceptor {
 
 			// Search
 			if (typeRestfulInteractions.contains(CapabilityStatement.TypeRestfulInteraction.SEARCHTYPE)) {
-				Operation operation = getPathItem(paths, "/" + resourceType, PathItem.HttpMethod.GET);
+				addSearchOperation(openApi, getPathItem(paths, "/" + resourceType, PathItem.HttpMethod.GET), ctx, resourceType, nextResource);
-				operation.addTagsItem(resourceType);
+				addSearchOperation(openApi, getPathItem(paths, "/" + resourceType + "/_search", PathItem.HttpMethod.GET), ctx, resourceType, nextResource);
-				operation.setDescription("This is a search type");
-				operation.setSummary("search-type: Search for " + resourceType + " instances");
-				addFhirResourceResponse(ctx, openApi, operation, null);
-
-				for (CapabilityStatement.CapabilityStatementRestResourceSearchParamComponent nextSearchParam : nextResource.getSearchParam()) {
-					Parameter parametersItem = new Parameter();
-					operation.addParametersItem(parametersItem);
-
-					parametersItem.setName(nextSearchParam.getName());
-					parametersItem.setIn("query");
-					parametersItem.setDescription(nextSearchParam.getDocumentation());
-					parametersItem.setStyle(Parameter.StyleEnum.SIMPLE);
-				}
 			}
 
 			// Resource-level Operations
@@ -596,6 +587,24 @@ public class OpenApiInterceptor {
 		return openApi;
 	}
 
+	protected void addSearchOperation(final OpenAPI openApi, final Operation operation, final FhirContext ctx,
+			final String resourceType, final CapabilityStatement.CapabilityStatementRestResourceComponent nextResource) {
+		operation.addTagsItem(resourceType);
+		operation.setDescription("This is a search type");
+		operation.setSummary("search-type: Search for " + resourceType + " instances");
+		addFhirResourceResponse(ctx, openApi, operation, null);
+
+		for (final CapabilityStatement.CapabilityStatementRestResourceSearchParamComponent nextSearchParam : nextResource.getSearchParam()) {
+			final Parameter parametersItem = new Parameter();
+			operation.addParametersItem(parametersItem);
+
+			parametersItem.setName(nextSearchParam.getName());
+			parametersItem.setIn("query");
+			parametersItem.setDescription(nextSearchParam.getDocumentation());
+			parametersItem.setStyle(Parameter.StyleEnum.SIMPLE);
+		}
+	}
+
 	private Supplier<IBaseResource> patchExampleSupplier() {
 		return () -> {
 			Parameters example = new Parameters();
@@ -650,8 +659,15 @@ public class OpenApiInterceptor {
 			}
 
 			OperationDefinition operationDefinition = toCanonicalVersion(operationDefinitionNonCanonical);
+			final boolean postOnly = operationDefinition.getAffectsState()
+					|| operationDefinition.getParameter().stream()
+					.filter(p -> p.getUse().equals(OperationParameterUse.IN))
+					.anyMatch(p -> {
+						final boolean required = p.getMin() > 0;
+						return required && !isPrimitive(p);
+					});
 
-			if (!operationDefinition.getAffectsState()) {
+			if (!postOnly) {
 
 				// GET form for non-state-affecting operations
 				if (theResourceType != null) {
@@ -671,7 +687,7 @@ public class OpenApiInterceptor {
 					}
 				}
 
-			} else {
+			}
 
 			// POST form for all operations
 			if (theResourceType != null) {
@@ -693,6 +709,33 @@ public class OpenApiInterceptor {
 
 		}
 	}
+
+	private static List<String> primitiveTypes = Arrays.asList(
+			DataTypes.BOOLEAN.toCode(),
+			DataTypes.INTEGER.toCode(),
+			DataTypes.STRING.toCode(),
+			DataTypes.DECIMAL.toCode(),
+			DataTypes.URI.toCode(),
+			DataTypes.URL.toCode(),
+			DataTypes.CANONICAL.toCode(),
+			DataTypes.REFERENCE.toCode(),
+			DataTypes.BASE64BINARY.toCode(),
+			DataTypes.INSTANT.toCode(),
+			DataTypes.DATE.toCode(),
+			DataTypes.DATETIME.toCode(),
+			DataTypes.TIME.toCode(),
+			DataTypes.CODE.toCode(),
+			DataTypes.CODING.toCode(),
+			DataTypes.OID.toCode(),
+			DataTypes.ID.toCode(),
+			DataTypes.MARKDOWN.toCode(),
+			DataTypes.UNSIGNEDINT.toCode(),
+			DataTypes.POSITIVEINT.toCode(),
+			DataTypes.UUID.toCode()
+			);
+
+	private static boolean isPrimitive(OperationDefinitionParameterComponent parameter) {
+		return primitiveTypes.contains(parameter.getType());
 	}
 
 	private void populateOperation(FhirContext theFhirContext, OpenAPI theOpenApi, String theResourceType, OperationDefinition theOperationDefinition, Operation theOperation, boolean theGet) {
@@ -704,10 +747,15 @@ public class OpenApiInterceptor {
 		theOperation.setSummary(theOperationDefinition.getTitle());
 		theOperation.setDescription(theOperationDefinition.getDescription());
 		addFhirResourceResponse(theFhirContext, theOpenApi, theOperation, null);
-
 		if (theGet) {
 
 			for (OperationDefinition.OperationDefinitionParameterComponent nextParameter : theOperationDefinition.getParameter()) {
+				if ("0".equals(nextParameter.getMax()) || !nextParameter.getUse().equals(OperationParameterUse.IN)) {
+					continue;
+				}
+				if (!isPrimitive(nextParameter) && nextParameter.getMin() == 0) {
+					continue;
+				}
 				Parameter parametersItem = new Parameter();
 				theOperation.addParametersItem(parametersItem);
 
@@ -733,6 +781,9 @@ public class OpenApiInterceptor {
 
 			Parameters exampleRequestBody = new Parameters();
 			for (OperationDefinition.OperationDefinitionParameterComponent nextSearchParam : theOperationDefinition.getParameter()) {
+				if ("0".equals(nextSearchParam.getMax()) || !nextSearchParam.getUse().equals(OperationParameterUse.IN)) {
+					continue;
+				}
 				Parameters.ParametersParameterComponent param = exampleRequestBody.addParameter();
 				param.setName(nextSearchParam.getName());
 				String paramType = nextSearchParam.getType();

hapi-fhir-server-openapi/src/test/java/ca/uhn/fhir/rest/openapi/OpenApiInterceptorTest.java

@@ -122,7 +122,11 @@ public class OpenApiInterceptorTest {
 		assertEquals("Foo Op Short", fooOpPath.getPost().getSummary());
 
 		PathItem lastNPath = parsed.getPaths().get("/Observation/$lastn");
-		assertNull(lastNPath.getPost());
+		assertNotNull(lastNPath.getPost());
+		assertEquals("LastN Description", lastNPath.getPost().getDescription());
+		assertEquals("LastN Short", lastNPath.getPost().getSummary());
+		assertNull(lastNPath.getPost().getParameters());
+		assertNotNull(lastNPath.getPost().getRequestBody());
 		assertNotNull(lastNPath.getGet());
 		assertEquals("LastN Description", lastNPath.getGet().getDescription());
 		assertEquals("LastN Short", lastNPath.getGet().getSummary());