Allow to specify hints with the functional web API

The most common use case is specifying JSON views.

ServerResponse.BodyBuilder#hint(String, Object) allows to
specify response body serialization hints.

ServerRequest#body(BodyExtractor, Map) allows to specify
request body extraction hints.

Issue: SPR-15030

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

@@ -19,10 +19,14 @@ package org.springframework.web.reactive.function;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
 
+import com.fasterxml.jackson.annotation.JsonView;
 import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
@@ -43,13 +47,20 @@ import org.springframework.http.codec.json.Jackson2JsonDecoder;
 import org.springframework.http.codec.xml.Jaxb2XmlDecoder;
 import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
 
+import static org.springframework.http.codec.json.AbstractJackson2Codec.JSON_VIEW_HINT;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
 /**
  * @author Arjen Poutsma
+ * @author Sebastien Deleuze
  */
 public class BodyExtractorsTests {
 
 	private BodyExtractor.Context context;
 
+	private Map<String, Object> hints;
+
 	@Before
 	public void createContext() {
 		final List<HttpMessageReader<?>> messageReaders = new ArrayList<>();
@@ -63,8 +74,12 @@ public class BodyExtractorsTests {
 			public Supplier<Stream<HttpMessageReader<?>>> messageReaders() {
 				return messageReaders::stream;
 			}
+			@Override
+			public Map<String, Object> hints() {
+				return hints;
+			}
 		};
-
+		this.hints = new HashMap();
 	}
 
 	@Test
@@ -87,6 +102,31 @@ public class BodyExtractorsTests {
 				.verify();
 	}
 
+	@Test
+	public void toMonoWithHints() throws Exception {
+		BodyExtractor<Mono<User>, ReactiveHttpInputMessage> extractor = BodyExtractors.toMono(User.class);
+		this.hints.put(JSON_VIEW_HINT, SafeToDeserialize.class);
+
+		DefaultDataBufferFactory factory = new DefaultDataBufferFactory();
+		DefaultDataBuffer dataBuffer =
+				factory.wrap(ByteBuffer.wrap("{\"username\":\"foo\",\"password\":\"bar\"}".getBytes(StandardCharsets.UTF_8)));
+		Flux<DataBuffer> body = Flux.just(dataBuffer);
+
+		MockServerHttpRequest request = new MockServerHttpRequest();
+		request.getHeaders().setContentType(MediaType.APPLICATION_JSON);
+		request.setBody(body);
+
+		Mono<User> result = extractor.extract(request, this.context);
+
+		StepVerifier.create(result)
+				.consumeNextWith(user -> {
+					assertEquals("foo", user.getUsername());
+					assertNull(user.getPassword());
+				})
+				.expectComplete()
+				.verify();
+	}
+
 	@Test
 	public void toFlux() throws Exception {
 		BodyExtractor<Flux<String>, ReactiveHttpInputMessage> extractor = BodyExtractors.toFlux(String.class);
@@ -107,6 +147,35 @@ public class BodyExtractorsTests {
 				.verify();
 	}
 
+	@Test
+	public void toFluxWithHints() throws Exception {
+		BodyExtractor<Flux<User>, ReactiveHttpInputMessage> extractor = BodyExtractors.toFlux(User.class);
+		this.hints.put(JSON_VIEW_HINT, SafeToDeserialize.class);
+
+		DefaultDataBufferFactory factory = new DefaultDataBufferFactory();
+		DefaultDataBuffer dataBuffer =
+				factory.wrap(ByteBuffer.wrap("[{\"username\":\"foo\",\"password\":\"bar\"},{\"username\":\"bar\",\"password\":\"baz\"}]".getBytes(StandardCharsets.UTF_8)));
+		Flux<DataBuffer> body = Flux.just(dataBuffer);
+
+		MockServerHttpRequest request = new MockServerHttpRequest();
+		request.getHeaders().setContentType(MediaType.APPLICATION_JSON);
+		request.setBody(body);
+
+		Flux<User> result = extractor.extract(request, this.context);
+
+		StepVerifier.create(result)
+				.consumeNextWith(user -> {
+					assertEquals("foo", user.getUsername());
+					assertNull(user.getPassword());
+				})
+				.consumeNextWith(user -> {
+					assertEquals("bar", user.getUsername());
+					assertNull(user.getPassword());
+				})
+				.expectComplete()
+				.verify();
+	}
+
 	@Test
 	public void toFluxUnacceptable() throws Exception {
 		BodyExtractor<Flux<String>, ReactiveHttpInputMessage> extractor = BodyExtractors.toFlux(String.class);
@@ -125,6 +194,10 @@ public class BodyExtractorsTests {
 			public Supplier<Stream<HttpMessageReader<?>>> messageReaders() {
 				return Stream::empty;
 			}
+			@Override
+			public Map<String, Object> hints() {
+				return Collections.emptyMap();
+			}
 		};
 
 		Flux<String> result = extractor.extract(request, emptyContext);
@@ -153,4 +226,39 @@ public class BodyExtractorsTests {
 				.verify();
 	}
 
+
+	interface SafeToDeserialize {}
+
+	private static class User {
+
+		@JsonView(SafeToDeserialize.class)
+		private String username;
+
+		private String password;
+
+		public User() {
+		}
+
+		public User(String username, String password) {
+			this.username = username;
+			this.password = password;
+		}
+
+		public String getUsername() {
+			return username;
+		}
+
+		public void setUsername(String username) {
+			this.username = username;
+		}
+
+		public String getPassword() {
+			return password;
+		}
+
+		public void setPassword(String password) {
+			this.password = password;
+		}
+	}
+
 }

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

@@ -21,10 +21,13 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
 
+import com.fasterxml.jackson.annotation.JsonView;
 import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
@@ -51,14 +54,18 @@ import org.springframework.mock.http.server.reactive.test.MockServerHttpResponse
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.junit.Assert.assertArrayEquals;
+import static org.springframework.http.codec.json.AbstractJackson2Codec.JSON_VIEW_HINT;
 
 /**
  * @author Arjen Poutsma
+ * @author Sebastien Deleuze
  */
 public class BodyInsertersTests {
 
 	private BodyInserter.Context context;
 
+	private Map<String, Object> hints;
+
 	@Before
 	public void createContext() {
 		final List<HttpMessageWriter<?>> messageWriters = new ArrayList<>();
@@ -71,19 +78,21 @@ public class BodyInsertersTests {
 		messageWriters
 				.add(new ServerSentEventHttpMessageWriter(Collections.singletonList(jsonEncoder)));
 
-
 		this.context = new BodyInserter.Context() {
 			@Override
 			public Supplier<Stream<HttpMessageWriter<?>>> messageWriters() {
 				return messageWriters::stream;
 			}
+			@Override
+			public Map<String, Object> hints() {
+				return hints;
+			}
 		};
-
+		this.hints = new HashMap();
 	}
 
-
 	@Test
-	public void ofObject() throws Exception {
+	public void ofString() throws Exception {
 		String body = "foo";
 		BodyInserter<String, ReactiveHttpOutputMessage> inserter = BodyInserters.fromObject(body);
 
@@ -99,6 +108,35 @@ public class BodyInsertersTests {
 				.verify();
 	}
 
+	@Test
+	public void ofObject() throws Exception {
+		User body = new User("foo", "bar");
+		BodyInserter<User, ReactiveHttpOutputMessage> inserter = BodyInserters.fromObject(body);
+		MockServerHttpResponse response = new MockServerHttpResponse();
+		Mono<Void> result = inserter.insert(response, this.context);
+		StepVerifier.create(result).expectComplete().verify();
+
+		StepVerifier.create(response.getBodyAsString())
+				.expectNext("{\"username\":\"foo\",\"password\":\"bar\"}")
+				.expectComplete()
+				.verify();
+	}
+
+	@Test
+	public void ofObjectWithHints() throws Exception {
+		User body = new User("foo", "bar");
+		BodyInserter<User, ReactiveHttpOutputMessage> inserter = BodyInserters.fromObject(body);
+		this.hints.put(JSON_VIEW_HINT, SafeToSerialize.class);
+		MockServerHttpResponse response = new MockServerHttpResponse();
+		Mono<Void> result = inserter.insert(response, this.context);
+		StepVerifier.create(result).expectComplete().verify();
+
+		StepVerifier.create(response.getBodyAsString())
+				.expectNext("{\"username\":\"foo\"}")
+				.expectComplete()
+				.verify();
+	}
+
 	@Test
 	public void ofPublisher() throws Exception {
 		Flux<String> body = Flux.just("foo");
@@ -180,4 +218,39 @@ public class BodyInsertersTests {
 	}
 
 
+	interface SafeToSerialize {}
+
+	private static class User {
+
+		@JsonView(SafeToSerialize.class)
+		private String username;
+
+		private String password;
+
+		public User() {
+		}
+
+		public User(String username, String password) {
+			this.username = username;
+			this.password = password;
+		}
+
+		public String getUsername() {
+			return username;
+		}
+
+		public void setUsername(String username) {
+			this.username = username;
+		}
+
+		public String getPassword() {
+			return password;
+		}
+
+		public void setPassword(String password) {
+			this.password = password;
+		}
+	}
+
+
 }

spring-web-reactive/src/test/java/org/springframework/web/reactive/function/server/MockServerRequest.java

@@ -99,6 +99,11 @@ public class MockServerRequest implements ServerRequest {
 		return (S) this.body;
 	}
 
+	@Override
+	public <S> S body(BodyExtractor<S, ? super ServerHttpRequest> extractor, Map<String, Object> hints) {
+		return (S) this.body;
+	}
+
 	@Override
 	@SuppressWarnings("unchecked")
 	public <S> Mono<S> bodyToMono(Class<? extends S> elementClass) {