Do not register SpringDataWebSettings if pageSerializationMode is default

allow application to register their own SpringDataWebSettings without @primary

see spring-projects/spring-boot#39797 (comment)

Author: quaff

src/main/java/org/springframework/data/web/config/EnableSpringDataWebSupport.java

@@ -69,6 +69,7 @@
  * @see SpringDataWebConfiguration
  * @see HateoasAwareSpringDataWebConfiguration
  * @author Oliver Gierke
+ * @author Yanming Zhou
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ ElementType.TYPE, ElementType.ANNOTATION_TYPE })
@@ -190,8 +191,16 @@ public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, B
 				return;
 			}
 
+			Object pageSerializationMode = attributes.get("pageSerializationMode");
+
+			if (pageSerializationMode == PageSerializationMode.DIRECT) {
+				// do not register SpringDataWebSettings if pageSerializationMode is default
+				// allow application to register their own SpringDataWebSettings without @Primary
+				return;
+			}
+
 			AbstractBeanDefinition definition = BeanDefinitionBuilder.rootBeanDefinition(SpringDataWebSettings.class)
-					.addConstructorArgValue(attributes.get("pageSerializationMode"))
+					.addConstructorArgValue(pageSerializationMode)
 					.getBeanDefinition();
 
 			String beanName = importBeanNameGenerator.generateBeanName(definition, registry);

src/main/java/org/springframework/data/web/config/SpringDataJacksonConfiguration.java

@@ -37,6 +37,7 @@
  * JavaConfig class to export Jackson specific configuration.
  *
  * @author Oliver Gierke
+ * @author Yanming Zhou
  */
 public class SpringDataJacksonConfiguration implements SpringDataJacksonModules {
 
@@ -84,7 +85,7 @@ public PageModule(@Nullable SpringDataWebSettings settings) {
 
 			addSerializer(UNPAGED_TYPE, new UnpagedAsInstanceSerializer());
 
-			if (settings != null && settings.pageSerializationMode() == PageSerializationMode.DIRECT) {
+			if (settings == null || settings.pageSerializationMode() == PageSerializationMode.DIRECT) {
 				setMixInAnnotation(PageImpl.class, WarningMixing.class);
 			} else {
 				setMixInAnnotation(PageImpl.class, WrappingMixing.class);

src/test/java/org/springframework/data/web/config/EnableSpringDataWebSupportIntegrationTests.java

@@ -24,6 +24,7 @@
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -67,7 +68,7 @@ class EnableSpringDataWebSupportIntegrationTests {
 
 	@Configuration
 	@EnableWebMvc
-	@EnableSpringDataWebSupport
+	@EnableSpringDataWebSupport(pageSerializationMode = EnableSpringDataWebSupport.PageSerializationMode.VIA_DTO)
 	static class SampleConfig {
 
 		@Bean
@@ -304,6 +305,10 @@ void registersSpringDataWebSettingsBean() {
 	void usesDirectPageSerializationMode() throws Exception {
 
 		var applicationContext = WebTestUtils.createApplicationContext(PageSampleConfigWithDirect.class);
+
+		// SpringDataWebSettings shouldn't be registered if pageSerializationMode is default
+		assertThatExceptionOfType(NoSuchBeanDefinitionException.class).isThrownBy(() -> applicationContext.getBean(SpringDataWebSettings.class));
+
 		var mvc = MockMvcBuilders.webAppContextSetup(applicationContext).build();
 
 		mvc.perform(post("/page"))//