Support application/graphql for request body

Closes gh-948

Author: rstoyanchev

spring-graphql/src/main/java/org/springframework/graphql/server/webflux/GraphQlHttpHandler.java

@@ -25,13 +25,16 @@
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.graphql.server.WebGraphQlHandler;
 import org.springframework.graphql.server.WebGraphQlRequest;
 import org.springframework.graphql.server.support.SerializableGraphQlRequest;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.util.Assert;
 import org.springframework.web.reactive.function.server.ServerRequest;
 import org.springframework.web.reactive.function.server.ServerResponse;
+import org.springframework.web.server.UnsupportedMediaTypeStatusException;
 
 /**
  * WebFlux.fn Handler for GraphQL over HTTP requests.
@@ -73,6 +76,9 @@ public GraphQlHttpHandler(WebGraphQlHandler graphQlHandler) {
 	 */
 	public Mono<ServerResponse> handleRequest(ServerRequest serverRequest) {
 		return serverRequest.bodyToMono(SerializableGraphQlRequest.class)
+				.onErrorResume(
+						UnsupportedMediaTypeStatusException.class,
+						(ex) -> applyApplicationGraphQlFallback(ex, serverRequest))
 				.flatMap((body) -> {
 					WebGraphQlRequest graphQlRequest = new WebGraphQlRequest(
 							serverRequest.uri(), serverRequest.headers().asHttpHeaders(),
@@ -95,6 +101,20 @@ public Mono<ServerResponse> handleRequest(ServerRequest serverRequest) {
 				});
 	}
 
+	private static Mono<SerializableGraphQlRequest> applyApplicationGraphQlFallback(
+			UnsupportedMediaTypeStatusException ex, ServerRequest request) {
+
+		// Spec requires application/json but some clients still use application/graphql
+		return "application/graphql".equals(request.headers().firstHeader(HttpHeaders.CONTENT_TYPE)) ?
+				ServerRequest.from(request)
+						.headers((headers) -> headers.setContentType(MediaType.APPLICATION_JSON))
+						.body(request.bodyToFlux(DataBuffer.class))
+						.build()
+						.bodyToMono(SerializableGraphQlRequest.class)
+						.log() :
+				Mono.error(ex);
+	}
+
 	private static MediaType selectResponseMediaType(ServerRequest serverRequest) {
 		for (MediaType accepted : serverRequest.headers().accept()) {
 			if (SUPPORTED_MEDIA_TYPES.contains(accepted)) {

spring-graphql/src/main/java/org/springframework/graphql/server/webmvc/GraphQlHttpHandler.java

@@ -35,6 +35,7 @@
 import org.springframework.graphql.server.WebGraphQlRequest;
 import org.springframework.graphql.server.support.SerializableGraphQlRequest;
 import org.springframework.http.HttpCookie;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.util.AlternativeJdkIdGenerator;
 import org.springframework.util.Assert;
@@ -146,6 +147,28 @@ private static GraphQlRequest readBody(ServerRequest request) throws ServletExce
 		catch (IOException ex) {
 			throw new ServerWebInputException("I/O error while reading request body", null, ex);
 		}
+		catch (HttpMediaTypeNotSupportedException ex) {
+			return applyApplicationGraphQlFallback(request, ex);
+		}
+	}
+
+	private static SerializableGraphQlRequest applyApplicationGraphQlFallback(
+			ServerRequest request, HttpMediaTypeNotSupportedException ex) throws HttpMediaTypeNotSupportedException {
+
+		// Spec requires application/json but some clients still use application/graphql
+		if ("application/graphql".equals(request.headers().firstHeader(HttpHeaders.CONTENT_TYPE))) {
+			try {
+				request = ServerRequest.from(request)
+						.headers((headers) -> headers.setContentType(MediaType.APPLICATION_JSON))
+						.body(request.body(byte[].class))
+						.build();
+				return request.body(SerializableGraphQlRequest.class);
+			}
+			catch (Throwable ex2) {
+				// ignore
+			}
+		}
+		throw ex;
 	}
 
 	private static MediaType selectResponseMediaType(ServerRequest serverRequest) {

spring-graphql/src/test/java/org/springframework/graphql/server/webflux/GraphQlHttpHandlerTests.java

@@ -75,6 +75,22 @@ void shouldProduceApplicationJsonByDefault() throws Exception {
 				.verifyComplete();
 	}
 
+	@Test
+	void shouldSupportApplicationGraphQl() throws Exception {
+		String document = "{greeting}";
+		MockServerHttpRequest httpRequest = MockServerHttpRequest.post("/")
+				.contentType(MediaType.parseMediaType("application/graphql"))
+				.accept(MediaType.ALL)
+				.body(initRequestBody(document));
+
+		MockServerHttpResponse response = handleRequest(httpRequest, this.greetingHandler);
+
+		assertThat(response.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
+		StepVerifier.create(response.getBodyAsString())
+				.expectNext("{\"data\":{\"greeting\":\"Hello\"}}")
+				.verifyComplete();
+	}
+
 	@Test
 	void shouldProduceApplicationGraphQl() throws Exception {
 		MockServerHttpRequest httpRequest = MockServerHttpRequest.post("/")

spring-graphql/src/test/java/org/springframework/graphql/server/webmvc/GraphQlHttpHandlerTests.java

@@ -36,6 +36,7 @@
 import org.springframework.graphql.GraphQlSetup;
 import org.springframework.graphql.server.support.SerializableGraphQlRequest;
 import org.springframework.http.MediaType;
+import org.springframework.http.converter.ByteArrayHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 import org.springframework.mock.web.MockHttpServletRequest;
@@ -55,7 +56,7 @@
 public class GraphQlHttpHandlerTests {
 
 	private static final List<HttpMessageConverter<?>> MESSAGE_READERS =
-			Collections.singletonList(new MappingJackson2HttpMessageConverter());
+			List.of(new MappingJackson2HttpMessageConverter(), new ByteArrayHttpMessageConverter());
 
 	private final GraphQlHttpHandler greetingHandler = GraphQlSetup.schemaContent("type Query { greeting: String }")
 			.queryFetcher("greeting", (env) -> "Hello").toHttpHandler();
@@ -66,6 +67,16 @@ void shouldProduceApplicationJsonByDefault() throws Exception {
 		MockHttpServletRequest request = createServletRequest("{ greeting }", "*/*");
 		MockHttpServletResponse response = handleRequest(request, this.greetingHandler);
 		assertThat(response.getContentType()).isEqualTo(MediaType.APPLICATION_JSON_VALUE);
+		assertThat(response.getContentAsString()).isEqualTo("{\"data\":{\"greeting\":\"Hello\"}}");
+	}
+
+	@Test
+	void shouldSupportApplicationGraphQl() throws Exception {
+		MockHttpServletRequest request = createServletRequest("{ greeting }", "*/*");
+		request.setContentType("application/graphql");
+
+		MockHttpServletResponse response = handleRequest(request, this.greetingHandler);
+		assertThat(response.getContentAsString()).isEqualTo("{\"data\":{\"greeting\":\"Hello\"}}");
 	}
 
 	@Test