ConnectionDataFetcher supports DataFetcherResult

Closes gh-835

Author: rstoyanchev

spring-graphql/src/main/java/org/springframework/graphql/data/pagination/ConnectionFieldTypeVisitor.java

@@ -23,6 +23,7 @@
 import java.util.concurrent.CompletionStage;
 
 import graphql.TrivialDataFetcher;
+import graphql.execution.DataFetcherResult;
 import graphql.relay.Connection;
 import graphql.relay.DefaultConnection;
 import graphql.relay.DefaultConnectionCursor;
@@ -189,17 +190,30 @@ private record ConnectionDataFetcher(DataFetcher<?> delegate, ConnectionAdapter
 		public Object get(DataFetchingEnvironment environment) throws Exception {
 			Object result = this.delegate.get(environment);
 			if (result instanceof Mono<?> mono) {
-				return mono.map(this::adapt);
+				return mono.map(this::adaptDataFetcherResult);
 			}
 			else if (result instanceof CompletionStage<?> stage) {
-				return stage.thenApply(this::adapt);
+				return stage.thenApply(this::adaptDataFetcherResult);
 			}
 			else {
-				return adapt(result);
+				return adaptDataFetcherResult(result);
 			}
 		}
 
-		private <T> Object adapt(@Nullable Object container) {
+		private Object adaptDataFetcherResult(@Nullable Object value) {
+			if (value instanceof DataFetcherResult<?> dataFetcherResult) {
+				Object adapted = adaptDataContainer(dataFetcherResult.getData());
+				return DataFetcherResult.newResult()
+						.data(adapted)
+						.errors(dataFetcherResult.getErrors())
+						.localContext(dataFetcherResult.getLocalContext()).build();
+			}
+			else {
+				return adaptDataContainer(value);
+			}
+		}
+
+		private <T> Object adaptDataContainer(@Nullable Object container) {
 			if (container == null) {
 				return EMPTY_CONNECTION;
 			}

spring-graphql/src/test/java/org/springframework/graphql/data/pagination/ConnectionFieldTypeVisitorTests.java

@@ -18,7 +18,9 @@
 
 import java.util.Collection;
 import java.util.List;
+import java.util.function.Consumer;
 
+import graphql.execution.DataFetcherResult;
 import graphql.schema.DataFetcher;
 import graphql.schema.FieldCoordinates;
 import graphql.schema.GraphQLFieldDefinition;
@@ -52,36 +54,41 @@ public class ConnectionFieldTypeVisitorTests {
 
 
 	@Test
-	void paginatedTypeIsAdapted() {
-
-		ListConnectionAdapter adapter = new ListConnectionAdapter();
-		adapter.setInitialOffset(30);
-		adapter.setHasNext(true);
-
-		Mono<ExecutionGraphQlResponse> response = GraphQlSetup.schemaResource(BookSource.paginationSchema)
-				.dataFetcher("Query", "books", env -> BookSource.books())
-				.connectionSupport(adapter)
-				.toGraphQlService()
-				.execute(BookSource.booksConnectionQuery(null));
-
-		ResponseHelper.forResponse(response).assertData(
-				"{\"books\":{" +
-						"\"edges\":[" +
-						"{\"cursor\":\"O_30\",\"node\":{\"id\":\"1\",\"name\":\"Nineteen Eighty-Four\"}}," +
-						"{\"cursor\":\"O_31\",\"node\":{\"id\":\"2\",\"name\":\"The Great Gatsby\"}}," +
-						"{\"cursor\":\"O_32\",\"node\":{\"id\":\"3\",\"name\":\"Catch-22\"}}," +
-						"{\"cursor\":\"O_33\",\"node\":{\"id\":\"4\",\"name\":\"To The Lighthouse\"}}," +
-						"{\"cursor\":\"O_34\",\"node\":{\"id\":\"5\",\"name\":\"Animal Farm\"}}," +
-						"{\"cursor\":\"O_35\",\"node\":{\"id\":\"53\",\"name\":\"Breaking Bad\"}}," +
-						"{\"cursor\":\"O_36\",\"node\":{\"id\":\"42\",\"name\":\"Hitchhiker's Guide to the Galaxy\"}}" +
-						"]," +
-						"\"pageInfo\":{" +
-						"\"startCursor\":\"O_30\"," +
-						"\"endCursor\":\"O_36\"," +
-						"\"hasPreviousPage\":true," +
-						"\"hasNextPage\":true}" +
-						"}}"
-		);
+	void adaptPaginatedType() {
+
+		Consumer<DataFetcher<Object>> testConsumer = booksDataFetcher -> {
+			ListConnectionAdapter adapter = new ListConnectionAdapter();
+			adapter.setInitialOffset(30);
+			adapter.setHasNext(true);
+
+			Mono<ExecutionGraphQlResponse> response = GraphQlSetup.schemaResource(BookSource.paginationSchema)
+					.dataFetcher("Query", "books", booksDataFetcher)
+					.connectionSupport(adapter)
+					.toGraphQlService()
+					.execute(BookSource.booksConnectionQuery(null));
+
+			ResponseHelper.forResponse(response).assertData(
+					"{\"books\":{" +
+							"\"edges\":[" +
+							"{\"cursor\":\"O_30\",\"node\":{\"id\":\"1\",\"name\":\"Nineteen Eighty-Four\"}}," +
+							"{\"cursor\":\"O_31\",\"node\":{\"id\":\"2\",\"name\":\"The Great Gatsby\"}}," +
+							"{\"cursor\":\"O_32\",\"node\":{\"id\":\"3\",\"name\":\"Catch-22\"}}," +
+							"{\"cursor\":\"O_33\",\"node\":{\"id\":\"4\",\"name\":\"To The Lighthouse\"}}," +
+							"{\"cursor\":\"O_34\",\"node\":{\"id\":\"5\",\"name\":\"Animal Farm\"}}," +
+							"{\"cursor\":\"O_35\",\"node\":{\"id\":\"53\",\"name\":\"Breaking Bad\"}}," +
+							"{\"cursor\":\"O_36\",\"node\":{\"id\":\"42\",\"name\":\"Hitchhiker's Guide to the Galaxy\"}}" +
+							"]," +
+							"\"pageInfo\":{" +
+							"\"startCursor\":\"O_30\"," +
+							"\"endCursor\":\"O_36\"," +
+							"\"hasPreviousPage\":true," +
+							"\"hasNextPage\":true}" +
+							"}}"
+			);
+		};
+
+		testConsumer.accept(env -> BookSource.books());
+		testConsumer.accept(env -> DataFetcherResult.newResult().data(BookSource.books()).build());
 	}
 
 	@Test // gh-709