Add support for Flux<Part> in BodyExtractors

This commit adds a `toParts` method in `BodyExtractors`, returning a
BodyExtractor<Part>.

spring-webflux/src/main/java/org/springframework/web/reactive/function/BodyExtractors.java

@@ -48,12 +48,14 @@ import org.springframework.util.MultiValueMap;
  */
 public abstract class BodyExtractors {
 
-	private static final ResolvableType FORM_TYPE =
+	private static final ResolvableType FORM_MAP_TYPE =
 			ResolvableType.forClassWithGenerics(MultiValueMap.class, String.class, String.class);
 
-	private static final ResolvableType MULTIPART_TYPE = ResolvableType.forClassWithGenerics(
+	private static final ResolvableType MULTIPART_MAP_TYPE = ResolvableType.forClassWithGenerics(
 			MultiValueMap.class, String.class, Part.class);
 
+	private static final ResolvableType PART_TYPE = ResolvableType.forClass(Part.class);
+
 
 	/**
 	 * Return a {@code BodyExtractor} that reads into a Reactor {@link Mono}.
@@ -133,15 +135,16 @@ public abstract class BodyExtractors {
 	public static BodyExtractor<Mono<MultiValueMap<String, String>>, ServerHttpRequest> toFormData() {
 		return (serverRequest, context) -> {
 			HttpMessageReader<MultiValueMap<String, String>> messageReader =
-					formMessageReader(context);
+					messageReader(FORM_MAP_TYPE, MediaType.APPLICATION_FORM_URLENCODED, context);
 			return context.serverResponse()
-					.map(serverResponse -> messageReader.readMono(FORM_TYPE, FORM_TYPE, serverRequest, serverResponse, context.hints()))
+					.map(serverResponse -> messageReader.readMono(FORM_MAP_TYPE, FORM_MAP_TYPE, serverRequest, serverResponse, context.hints()))
-					.orElseGet(() -> messageReader.readMono(FORM_TYPE, serverRequest, context.hints()));
+					.orElseGet(() -> messageReader.readMono(FORM_MAP_TYPE, serverRequest, context.hints()));
 		};
 	}
 
 	/**
-	 * Return a {@code BodyExtractor} that reads form data into a {@link MultiValueMap}.
+	 * Return a {@code BodyExtractor} that reads multipart (i.e. file upload) form data into a
+	 * {@link MultiValueMap}.
 	 * @return a {@code BodyExtractor} that reads multipart data
 	 */
 	// Note that the returned BodyExtractor is parameterized to ServerHttpRequest, not
@@ -150,10 +153,29 @@ public abstract class BodyExtractors {
 	public static BodyExtractor<Mono<MultiValueMap<String, Part>>, ServerHttpRequest> toMultipartData() {
 		return (serverRequest, context) -> {
 			HttpMessageReader<MultiValueMap<String, Part>> messageReader =
-					multipartMessageReader(context);
+					messageReader(MULTIPART_MAP_TYPE, MediaType.MULTIPART_FORM_DATA, context);
 			return context.serverResponse()
-					.map(serverResponse -> messageReader.readMono(MULTIPART_TYPE, MULTIPART_TYPE, serverRequest, serverResponse, context.hints()))
+					.map(serverResponse -> messageReader.readMono(MULTIPART_MAP_TYPE,
-					.orElseGet(() -> messageReader.readMono(MULTIPART_TYPE, serverRequest, context.hints()));
+							MULTIPART_MAP_TYPE, serverRequest, serverResponse, context.hints()))
+					.orElseGet(() -> messageReader.readMono(MULTIPART_MAP_TYPE, serverRequest, context.hints()));
+		};
+	}
+
+	/**
+	 * Return a {@code BodyExtractor} that reads multipart (i.e. file upload) form data into a
+	 * {@link MultiValueMap}.
+	 * @return a {@code BodyExtractor} that reads multipart data
+	 */
+	// Note that the returned BodyExtractor is parameterized to ServerHttpRequest, not
+	// ReactiveHttpInputMessage like other methods, since reading form data only typically happens on
+	// the server-side
+	public static BodyExtractor<Flux<Part>, ServerHttpRequest> toParts() {
+		return (serverRequest, context) -> {
+			HttpMessageReader<Part> messageReader =
+					messageReader(PART_TYPE, MediaType.MULTIPART_FORM_DATA, context);
+			return context.serverResponse()
+					.map(serverResponse -> messageReader.read(PART_TYPE, PART_TYPE, serverRequest, serverResponse, context.hints()))
+					.orElseGet(() -> messageReader.read(PART_TYPE, serverRequest, context.hints()));
 		};
 	}
 
@@ -191,26 +213,15 @@ public abstract class BodyExtractors {
 				});
 	}
 
-	private static HttpMessageReader<MultiValueMap<String, String>> formMessageReader(BodyExtractor.Context context) {
+	private static <T> HttpMessageReader<T> messageReader(ResolvableType elementType,
+			MediaType mediaType, BodyExtractor.Context context) {
 		return context.messageReaders().get()
-				.filter(messageReader -> messageReader
+				.filter(messageReader -> messageReader.canRead(elementType, mediaType))
-						.canRead(FORM_TYPE, MediaType.APPLICATION_FORM_URLENCODED))
 				.findFirst()
-				.map(BodyExtractors::<MultiValueMap<String, String>>cast)
+				.map(BodyExtractors::<T>cast)
 				.orElseThrow(() -> new IllegalStateException(
-						"Could not find HttpMessageReader that supports " +
+						"Could not find HttpMessageReader that supports \"" + mediaType +
-								MediaType.APPLICATION_FORM_URLENCODED_VALUE));
+								"\" and \"" + elementType + "\""));
-	}
-
-	private static HttpMessageReader<MultiValueMap<String, Part>> multipartMessageReader(BodyExtractor.Context context) {
-		return context.messageReaders().get()
-				.filter(messageReader -> messageReader
-						.canRead(MULTIPART_TYPE, MediaType.MULTIPART_FORM_DATA))
-				.findFirst()
-				.map(BodyExtractors::<MultiValueMap<String, Part>>cast)
-				.orElseThrow(() -> new IllegalStateException(
-						"Could not find HttpMessageReader that supports " +
-								MediaType.MULTIPART_FORM_DATA));
 	}
 
 	private static MediaType contentType(HttpMessage message) {

spring-webflux/src/test/java/org/springframework/web/reactive/function/BodyExtractorsTests.java

@@ -36,6 +36,8 @@ import reactor.test.StepVerifier;
 
 import org.springframework.core.codec.ByteBufferDecoder;
 import org.springframework.core.codec.StringDecoder;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DefaultDataBuffer;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
@@ -45,10 +47,16 @@ import org.springframework.http.codec.DecoderHttpMessageReader;
 import org.springframework.http.codec.FormHttpMessageReader;
 import org.springframework.http.codec.HttpMessageReader;
 import org.springframework.http.codec.json.Jackson2JsonDecoder;
+import org.springframework.http.codec.multipart.FilePart;
+import org.springframework.http.codec.multipart.FormFieldPart;
+import org.springframework.http.codec.multipart.MultipartHttpMessageReader;
+import org.springframework.http.codec.multipart.Part;
+import org.springframework.http.codec.multipart.SynchronossPartHttpMessageReader;
 import org.springframework.http.codec.xml.Jaxb2XmlDecoder;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
+import org.springframework.util.FileCopyUtils;
 import org.springframework.util.MultiValueMap;
 
 import static org.junit.Assert.*;
@@ -72,6 +80,11 @@ public class BodyExtractorsTests {
 		messageReaders.add(new DecoderHttpMessageReader<>(StringDecoder.allMimeTypes(true)));
 		messageReaders.add(new DecoderHttpMessageReader<>(new Jaxb2XmlDecoder()));
 		messageReaders.add(new DecoderHttpMessageReader<>(new Jackson2JsonDecoder()));
+		messageReaders.add(new FormHttpMessageReader());
+		SynchronossPartHttpMessageReader partReader = new SynchronossPartHttpMessageReader();
+		messageReaders.add(partReader);
+		messageReaders.add(new MultipartHttpMessageReader(partReader));
+
 		messageReaders.add(new FormHttpMessageReader());
 
 		this.context = new BodyExtractor.Context() {
@@ -249,6 +262,64 @@ public class BodyExtractorsTests {
 				.verify();
 	}
 
+	@Test
+	public void toParts() throws Exception {
+		BodyExtractor<Flux<Part>, ServerHttpRequest> extractor = BodyExtractors.toParts();
+
+		String bodyContents = "-----------------------------9051914041544843365972754266\r\n" +
+				"Content-Disposition: form-data; name=\"text\"\r\n" +
+				"\r\n" +
+				"text default\r\n" +
+				"-----------------------------9051914041544843365972754266\r\n" +
+				"Content-Disposition: form-data; name=\"file1\"; filename=\"a.txt\"\r\n" +
+				"Content-Type: text/plain\r\n" +
+				"\r\n" +
+				"Content of a.txt.\r\n" +
+				"\r\n" +
+				"-----------------------------9051914041544843365972754266\r\n" +
+				"Content-Disposition: form-data; name=\"file2\"; filename=\"a.html\"\r\n" +
+				"Content-Type: text/html\r\n" +
+				"\r\n" +
+				"<!DOCTYPE html><title>Content of a.html.</title>\r\n" +
+				"\r\n" +
+				"-----------------------------9051914041544843365972754266--\r\n";
+
+		DefaultDataBufferFactory factory = new DefaultDataBufferFactory();
+		DefaultDataBuffer dataBuffer =
+				factory.wrap(ByteBuffer.wrap(bodyContents.getBytes(StandardCharsets.UTF_8)));
+		Flux<DataBuffer> body = Flux.just(dataBuffer);
+
+		MockServerHttpRequest request = MockServerHttpRequest.post("/")
+				.header("Content-Type", "multipart/form-data; boundary=---------------------------9051914041544843365972754266")
+				.body(body);
+
+		Flux<Part> result = extractor.extract(request, this.context);
+
+		StepVerifier.create(result)
+				.consumeNextWith(part -> {
+					assertEquals("text", part.getName());
+					assertTrue(part instanceof FormFieldPart);
+					FormFieldPart formFieldPart = (FormFieldPart) part;
+					assertEquals("text default", formFieldPart.getValue());
+				})
+				.consumeNextWith(part -> {
+					assertEquals("file1", part.getName());
+					assertTrue(part instanceof FilePart);
+					FilePart filePart = (FilePart) part;
+					assertEquals("a.txt", filePart.getFilename());
+					assertEquals(MediaType.TEXT_PLAIN, filePart.getHeaders().getContentType());
+				})
+				.consumeNextWith(part -> {
+					assertEquals("file2", part.getName());
+					assertTrue(part instanceof FilePart);
+					FilePart filePart = (FilePart) part;
+					assertEquals("a.html", filePart.getFilename());
+					assertEquals(MediaType.TEXT_HTML, filePart.getHeaders().getContentType());
+				})
+				.expectComplete()
+				.verify();
+	}
+
 	@Test
 	public void toDataBuffers() throws Exception {
 		BodyExtractor<Flux<DataBuffer>, ReactiveHttpInputMessage> extractor = BodyExtractors.toDataBuffers();

spring-webflux/src/test/java/org/springframework/web/reactive/function/MultipartIntegrationTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.web.reactive.function;
 
+import java.util.List;
 import java.util.Map;
 
 import org.junit.Test;
@@ -48,10 +49,25 @@ public class MultipartIntegrationTests extends AbstractRouterFunctionIntegration
 	private final WebClient webClient = WebClient.create();
 
 	@Test
-	public void multipart() {
+	public void multipartData() {
 		Mono<ClientResponse> result = webClient
 				.post()
-				.uri("http://localhost:" + this.port + "/")
+				.uri("http://localhost:" + this.port + "/multipartData")
+				.contentType(MediaType.MULTIPART_FORM_DATA)
+				.body(BodyInserters.fromMultipartData(generateBody()))
+				.exchange();
+
+		StepVerifier
+				.create(result)
+				.consumeNextWith(response -> assertEquals(HttpStatus.OK, response.statusCode()))
+				.verifyComplete();
+	}
+
+	@Test
+	public void parts() {
+		Mono<ClientResponse> result = webClient
+				.post()
+				.uri("http://localhost:" + this.port + "/parts")
 				.contentType(MediaType.MULTIPART_FORM_DATA)
 				.body(BodyInserters.fromMultipartData(generateBody()))
 				.exchange();
@@ -77,12 +93,13 @@ public class MultipartIntegrationTests extends AbstractRouterFunctionIntegration
 	@Override
 	protected RouterFunction<ServerResponse> routerFunction() {
 		MultipartHandler multipartHandler = new MultipartHandler();
-		return route(POST("/"), multipartHandler::handle);
+		return route(POST("/multipartData"), multipartHandler::multipartData)
+				.andRoute(POST("/parts"), multipartHandler::parts);
 	}
 
 	private static class MultipartHandler {
 
-		public Mono<ServerResponse> handle(ServerRequest request) {
+		public Mono<ServerResponse> multipartData(ServerRequest request) {
 			return request
 					.body(BodyExtractors.toMultipartData())
 					.flatMap(map -> {
@@ -98,6 +115,21 @@ public class MultipartIntegrationTests extends AbstractRouterFunctionIntegration
 						return ServerResponse.ok().build();
 					});
 		}
+
+		public Mono<ServerResponse> parts(ServerRequest request) {
+			return request.body(BodyExtractors.toParts()).collectList()
+					.flatMap(parts -> {
+						try {
+							assertEquals(2, parts.size());
+							assertEquals("foo.txt", ((FilePart) parts.get(0)).getFilename());
+							assertEquals("bar", ((FormFieldPart) parts.get(1)).getValue());
+						}
+						catch(Exception e) {
+							return Mono.error(e);
+						}
+						return ServerResponse.ok().build();
+					});
+		}
 	}
 
 }