Make ExtendedServletRequestDataBinder public

Make it public and move it down to the annotations package alongside
InitBinderBindingContext. This is mirrors the hierarchy in Spring MVC
with the ExtendedServletRequestDataBinder. The change will allow
customization of the header names to include/exclude in data binding.

See gh-34039

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

@@ -18,19 +18,14 @@ package org.springframework.web.reactive;
 
 import java.lang.annotation.Annotation;
 import java.util.Collection;
-import java.util.List;
 import java.util.Map;
 
-import reactor.core.publisher.Mono;
-
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.ResolvableType;
-import org.springframework.http.HttpHeaders;
 import org.springframework.lang.Nullable;
 import org.springframework.ui.Model;
-import org.springframework.util.CollectionUtils;
 import org.springframework.validation.BindingResult;
 import org.springframework.validation.DataBinder;
 import org.springframework.validation.SmartValidator;
@@ -141,7 +136,7 @@ public class BindingContext {
 	public WebExchangeDataBinder createDataBinder(
 			ServerWebExchange exchange, @Nullable Object target, String name, @Nullable ResolvableType targetType) {
 
-		WebExchangeDataBinder dataBinder = new ExtendedWebExchangeDataBinder(target, name);
+		WebExchangeDataBinder dataBinder = createBinderInstance(target, name);
 		dataBinder.setNameResolver(new BindParamNameResolver());
 
 		if (target == null && targetType != null) {
@@ -163,6 +158,18 @@ public class BindingContext {
 		return dataBinder;
 	}
 
+	/**
+	 * Extension point to create the WebDataBinder instance.
+	 * By default, this is {@code WebRequestDataBinder}.
+	 * @param target the binding target or {@code null} for type conversion only
+	 * @param name the binding target object name
+	 * @return the created {@link WebExchangeDataBinder} instance
+	 * @since 6.2.1
+	 */
+	protected WebExchangeDataBinder createBinderInstance(@Nullable Object target, String name) {
+		return new WebExchangeDataBinder(target, name);
+	}
+
 	/**
 	 * Initialize the data binder instance for the given exchange.
 	 * @throws ServerErrorException if {@code @InitBinder} method invocation fails
@@ -200,51 +207,6 @@ public class BindingContext {
 	}
 
 
-	/**
-	 * Extended variant of {@link WebExchangeDataBinder}, adding path variables.
-	 */
-	private static class ExtendedWebExchangeDataBinder extends WebExchangeDataBinder {
-
-		public ExtendedWebExchangeDataBinder(@Nullable Object target, String objectName) {
-			super(target, objectName);
-		}
-
-		@Override
-		public Mono<Map<String, Object>> getValuesToBind(ServerWebExchange exchange) {
-			return super.getValuesToBind(exchange).doOnNext(map -> {
-				Map<String, String> vars = exchange.getAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE);
-				if (!CollectionUtils.isEmpty(vars)) {
-					vars.forEach((key, value) -> addValueIfNotPresent(map, "URI variable", key, value));
-				}
-				HttpHeaders headers = exchange.getRequest().getHeaders();
-				for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
-					List<String> values = entry.getValue();
-					if (!CollectionUtils.isEmpty(values)) {
-						String name = entry.getKey().replace("-", "");
-						addValueIfNotPresent(map, "Header", name, (values.size() == 1 ? values.get(0) : values));
-					}
-				}
-			});
-		}
-
-		private static void addValueIfNotPresent(
-				Map<String, Object> map, String label, String name, @Nullable Object value) {
-
-			if (value != null) {
-				if (map.containsKey(name)) {
-					if (logger.isDebugEnabled()) {
-						logger.debug(label + " '" + name + "' overridden by request bind value.");
-					}
-				}
-				else {
-					map.put(name, value);
-				}
-			}
-		}
-
-	}
-
-
 	/**
 	 * Excludes Bean Validation if the method parameter has {@code @Valid}.
 	 */

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ExtendedWebExchangeDataBinder.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2002-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.reactive.result.method.annotation;
+
+import java.util.List;
+import java.util.Map;
+
+import reactor.core.publisher.Mono;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
+import org.springframework.util.CollectionUtils;
+import org.springframework.web.bind.support.WebExchangeDataBinder;
+import org.springframework.web.reactive.HandlerMapping;
+import org.springframework.web.server.ServerWebExchange;
+
+/**
+ * Extended variant of {@link WebExchangeDataBinder} that adds URI path variables
+ * and request headers to the bind values map.
+ *
+ * <p>Note: This class has existed since 5.0, but only as a private class within
+ * {@link org.springframework.web.reactive.BindingContext}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 6.2.1
+ */
+public class ExtendedWebExchangeDataBinder extends WebExchangeDataBinder {
+
+
+	public ExtendedWebExchangeDataBinder(@Nullable Object target, String objectName) {
+		super(target, objectName);
+	}
+
+
+	@Override
+	public Mono<Map<String, Object>> getValuesToBind(ServerWebExchange exchange) {
+		return super.getValuesToBind(exchange).doOnNext(map -> {
+			Map<String, String> vars = exchange.getAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE);
+			if (!CollectionUtils.isEmpty(vars)) {
+				vars.forEach((key, value) -> addValueIfNotPresent(map, "URI variable", key, value));
+			}
+			HttpHeaders headers = exchange.getRequest().getHeaders();
+			for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
+				List<String> values = entry.getValue();
+				if (!CollectionUtils.isEmpty(values)) {
+					String name = entry.getKey().replace("-", "");
+					addValueIfNotPresent(map, "Header", name, (values.size() == 1 ? values.get(0) : values));
+				}
+			}
+		});
+	}
+
+	private static void addValueIfNotPresent(
+			Map<String, Object> map, String label, String name, @Nullable Object value) {
+
+		if (value != null) {
+			if (map.containsKey(name)) {
+				if (logger.isDebugEnabled()) {
+					logger.debug(label + " '" + name + "' overridden by request bind value.");
+				}
+			}
+			else {
+				map.put(name, value);
+			}
+		}
+	}
+
+}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/InitBinderBindingContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -71,6 +71,15 @@ class InitBinderBindingContext extends BindingContext {
 	}
 
 
+	/**
+	 * Returns an instance of {@link ExtendedWebExchangeDataBinder}.
+	 * @since 6.2.1
+	 */
+	@Override
+	protected WebExchangeDataBinder createBinderInstance(@Nullable Object target, String name) {
+		return new ExtendedWebExchangeDataBinder(target, name);
+	}
+
 	@Override
 	protected WebExchangeDataBinder initDataBinder(WebExchangeDataBinder dataBinder, ServerWebExchange exchange) {
 		this.binderMethods.stream()

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

@@ -17,20 +17,16 @@
 package org.springframework.web.reactive;
 
 import java.lang.reflect.Method;
-import java.util.Map;
 
 import jakarta.validation.Valid;
 import org.junit.jupiter.api.Test;
 
-import org.springframework.beans.testfixture.beans.TestBean;
 import org.springframework.core.ResolvableType;
-import org.springframework.http.MediaType;
 import org.springframework.validation.Errors;
 import org.springframework.validation.SmartValidator;
 import org.springframework.validation.Validator;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.bind.WebDataBinder;
-import org.springframework.web.bind.support.WebExchangeDataBinder;
 import org.springframework.web.testfixture.http.server.reactive.MockServerHttpRequest;
 import org.springframework.web.testfixture.server.MockServerWebExchange;
 
@@ -68,54 +64,6 @@ class BindingContextTests {
 		assertThat(binder.getValidatorsToApply()).containsExactly(springValidator);
 	}
 
-	@Test
-	void bindUriVariablesAndHeaders() {
-
-		MockServerHttpRequest request = MockServerHttpRequest.get("/path")
-				.header("Some-Int-Array", "1")
-				.header("Some-Int-Array", "2")
-				.build();
-
-		MockServerWebExchange exchange = MockServerWebExchange.from(request);
-		exchange.getAttributes().put(
-				HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE,
-				Map.of("name", "John", "age", "25"));
-
-		TestBean target = new TestBean();
-
-		BindingContext bindingContext = new BindingContext(null);
-		WebExchangeDataBinder binder = bindingContext.createDataBinder(exchange, target, "testBean", null);
-
-		binder.bind(exchange).block();
-
-		assertThat(target.getName()).isEqualTo("John");
-		assertThat(target.getAge()).isEqualTo(25);
-		assertThat(target.getSomeIntArray()).containsExactly(1, 2);
-	}
-
-	@Test
-	void bindUriVarsAndHeadersAddedConditionally() {
-
-		MockServerHttpRequest request = MockServerHttpRequest.post("/path")
-				.header("name", "Johnny")
-				.contentType(MediaType.APPLICATION_FORM_URLENCODED)
-				.body("name=John&age=25");
-
-		MockServerWebExchange exchange = MockServerWebExchange.from(request);
-		exchange.getAttributes().put(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, Map.of("age", "26"));
-
-		TestBean target = new TestBean();
-
-		BindingContext bindingContext = new BindingContext(null);
-		WebExchangeDataBinder binder = bindingContext.createDataBinder(exchange, target, "testBean", null);
-
-		binder.bind(exchange).block();
-
-		assertThat(target.getName()).isEqualTo("John");
-		assertThat(target.getAge()).isEqualTo(25);
-	}
-
-
 	@SuppressWarnings("unused")
 	private void handleValidObject(@Valid Foo foo) {
 	}

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/InitBinderBindingContextTests.java

@@ -20,18 +20,23 @@ import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.beans.testfixture.beans.TestBean;
 import org.springframework.core.DefaultParameterNameDiscoverer;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.format.support.DefaultFormattingConversionService;
+import org.springframework.http.MediaType;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.annotation.InitBinder;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
+import org.springframework.web.bind.support.WebExchangeDataBinder;
 import org.springframework.web.reactive.BindingContext;
+import org.springframework.web.reactive.HandlerMapping;
 import org.springframework.web.reactive.result.method.SyncHandlerMethodArgumentResolver;
 import org.springframework.web.reactive.result.method.SyncInvocableHandlerMethod;
 import org.springframework.web.testfixture.http.server.reactive.MockServerHttpRequest;
@@ -123,6 +128,52 @@ class InitBinderBindingContextTests {
 		assertThat(dataBinder.getDisallowedFields()[0]).isEqualToIgnoringCase("requestParam-22");
 	}
 
+	@Test
+	void bindUriVariablesAndHeaders() throws Exception {
+
+		MockServerHttpRequest request = MockServerHttpRequest.get("/path")
+				.header("Some-Int-Array", "1")
+				.header("Some-Int-Array", "2")
+				.build();
+
+		MockServerWebExchange exchange = MockServerWebExchange.from(request);
+		exchange.getAttributes().put(
+				HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE,
+				Map.of("name", "John", "age", "25"));
+
+		TestBean target = new TestBean();
+
+		BindingContext context = createBindingContext("initBinderWithAttributeName", WebDataBinder.class);
+		WebExchangeDataBinder binder = context.createDataBinder(exchange, target, "testBean", null);
+
+		binder.bind(exchange).block();
+
+		assertThat(target.getName()).isEqualTo("John");
+		assertThat(target.getAge()).isEqualTo(25);
+		assertThat(target.getSomeIntArray()).containsExactly(1, 2);
+	}
+
+	@Test
+	void bindUriVarsAndHeadersAddedConditionally() throws Exception {
+
+		MockServerHttpRequest request = MockServerHttpRequest.post("/path")
+				.header("name", "Johnny")
+				.contentType(MediaType.APPLICATION_FORM_URLENCODED)
+				.body("name=John&age=25");
+
+		MockServerWebExchange exchange = MockServerWebExchange.from(request);
+		exchange.getAttributes().put(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, Map.of("age", "26"));
+
+		TestBean target = new TestBean();
+
+		BindingContext context = createBindingContext("initBinderWithAttributeName", WebDataBinder.class);
+		WebExchangeDataBinder binder = context.createDataBinder(exchange, target, "testBean", null);
+
+		binder.bind(exchange).block();
+
+		assertThat(target.getName()).isEqualTo("John");
+		assertThat(target.getAge()).isEqualTo(25);
+	}
 
 	private BindingContext createBindingContext(String methodName, Class<?>... parameterTypes) throws Exception {
 		Object handler = new InitBinderHandler();