DATACMNS-1231 - Add reactive auditing infrastructure.

We now provide a reactive variant for auditing with ReactiveAuditingHandler and ReactiveIsNewAwareAuditingHandler.

Extracted common auditing functionality into AuditingHandlerSupport which serves as base class for AuditingHandler and ReactiveAuditingHandler.

Original Pull Request: #458

Author: mp911de

src/main/asciidoc/auditing.adoc

@@ -41,19 +41,49 @@ In case you use either `@CreatedBy` or `@LastModifiedBy`, the auditing infrastru
 
 The following example shows an implementation of the interface that uses Spring Security's `Authentication` object:
 
-.Implementation of AuditorAware based on Spring Security
+.Implementation of `AuditorAware` based on Spring Security
 ====
 [source, java]
 ----
 class SpringSecurityAuditorAware implements AuditorAware<User> {
 
+  @Override
   public Optional<User> getCurrentAuditor() {
 
     return Optional.ofNullable(SecurityContextHolder.getContext())
-			  .map(SecurityContext::getAuthentication)
-			  .filter(Authentication::isAuthenticated)
-			  .map(Authentication::getPrincipal)
-			  .map(User.class::cast);
+            .map(SecurityContext::getAuthentication)
+            .filter(Authentication::isAuthenticated)
+            .map(Authentication::getPrincipal)
+            .map(User.class::cast);
+  }
+}
+----
+====
+
+The implementation accesses the `Authentication` object provided by Spring Security and looks up the custom `UserDetails` instance that you have created in your `UserDetailsService` implementation. We assume here that you are exposing the domain user through the `UserDetails` implementation but that, based on the `Authentication` found, you could also look it up from anywhere.
+
+[[auditing.reactive-auditor-aware]]
+=== `ReactiveAuditorAware`
+
+When using reactive infrastructure you might want to make use of contextual information to provide `@CreatedBy` or `@LastModifiedBy` information.
+We provide an `ReactiveAuditorAware<T>` SPI interface that you have to implement to tell the infrastructure who the current user or system interacting with the application is. The generic type `T` defines what type the properties annotated with `@CreatedBy` or `@LastModifiedBy` have to be.
+
+The following example shows an implementation of the interface that uses reactive Spring Security's `Authentication` object:
+
+.Implementation of `ReactiveAuditorAware` based on Spring Security
+====
+[source, java]
+----
+class SpringSecurityAuditorAware implements ReactiveAuditorAware<User> {
+
+  @Override
+  public Mono<User> getCurrentAuditor() {
+
+    return ReactiveSecurityContextHolder.getContext()
+                .map(SecurityContext::getAuthentication)
+                .filter(Authentication::isAuthenticated)
+                .map(Authentication::getPrincipal)
+                .map(User.class::cast);
   }
 }
 ----

src/main/java/org/springframework/data/auditing/AuditingHandler.java

@@ -15,16 +15,12 @@
  */
 package org.springframework.data.auditing;
 
-import java.time.temporal.TemporalAccessor;
 import java.util.Optional;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.joda.time.DateTime;
-import org.springframework.aop.support.AopUtils;
+
 import org.springframework.beans.factory.InitializingBean;
-import org.springframework.core.log.LogMessage;
-import org.springframework.data.domain.Auditable;
 import org.springframework.data.domain.AuditorAware;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
@@ -39,16 +35,11 @@
  * @author Christoph Strobl
  * @since 1.5
  */
-public class AuditingHandler implements InitializingBean {
+public class AuditingHandler extends AuditingHandlerSupport implements InitializingBean {
 
 	private static final Log logger = LogFactory.getLog(AuditingHandler.class);
 
-	private final DefaultAuditableBeanWrapperFactory factory;
-
-	private DateTimeProvider dateTimeProvider = CurrentDateTimeProvider.INSTANCE;
 	private Optional<AuditorAware<?>> auditorAware;
-	private boolean dateTimeForNow = true;
-	private boolean modifyOnCreation = true;
 
 	/**
 	 * Creates a new {@link AuditableBeanWrapper} using the given {@link MappingContext} when looking up auditing metadata
@@ -73,9 +64,9 @@ public AuditingHandler(
 	 */
 	public AuditingHandler(PersistentEntities entities) {
 
+		super(entities);
 		Assert.notNull(entities, "PersistentEntities must not be null!");
 
-		this.factory = new MappingAuditableBeanWrapperFactory(entities);
 		this.auditorAware = Optional.empty();
 	}
 
@@ -90,36 +81,6 @@ public void setAuditorAware(AuditorAware<?> auditorAware) {
 		this.auditorAware = Optional.of(auditorAware);
 	}
 
-	/**
-	 * Setter do determine if {@link Auditable#setCreatedDate(DateTime)} and
-	 * {@link Auditable#setLastModifiedDate(DateTime)} shall be filled with the current Java time. Defaults to
-	 * {@code true}. One might set this to {@code false} to use database features to set entity time.
-	 *
-	 * @param dateTimeForNow the dateTimeForNow to set
-	 */
-	public void setDateTimeForNow(boolean dateTimeForNow) {
-		this.dateTimeForNow = dateTimeForNow;
-	}
-
-	/**
-	 * Set this to true if you want to treat entity creation as modification and thus setting the current date as
-	 * modification date during creation, too. Defaults to {@code true}.
-	 *
-	 * @param modifyOnCreation if modification information shall be set on creation, too
-	 */
-	public void setModifyOnCreation(boolean modifyOnCreation) {
-		this.modifyOnCreation = modifyOnCreation;
-	}
-
-	/**
-	 * Sets the {@link DateTimeProvider} to be used to determine the dates to be set.
-	 *
-	 * @param dateTimeProvider
-	 */
-	public void setDateTimeProvider(DateTimeProvider dateTimeProvider) {
-		this.dateTimeProvider = dateTimeProvider == null ? CurrentDateTimeProvider.INSTANCE : dateTimeProvider;
-	}
-
 	/**
 	 * Marks the given object as created.
 	 *
@@ -129,7 +90,7 @@ public <T> T markCreated(T source) {
 
 		Assert.notNull(source, "Entity must not be null!");
 
-		return touch(source, true);
+		return markCreated(auditorAware.flatMap(AuditorAware::getCurrentAuditor).orElse(null), source);
 	}
 
 	/**
@@ -141,86 +102,7 @@ public <T> T markModified(T source) {
 
 		Assert.notNull(source, "Entity must not be null!");
 
-		return touch(source, false);
-	}
-
-	/**
-	 * Returns whether the given source is considered to be auditable in the first place
-	 *
-	 * @param source must not be {@literal null}.
-	 * @return
-	 */
-	protected final boolean isAuditable(Object source) {
-
-		Assert.notNull(source, "Source must not be null!");
-
-		return factory.getBeanWrapperFor(source).isPresent();
-	}
-
-	private <T> T touch(T target, boolean isNew) {
-
-		Optional<AuditableBeanWrapper<T>> wrapper = factory.getBeanWrapperFor(target);
-
-		return wrapper.map(it -> {
-
-			Optional<Object> auditor = touchAuditor(it, isNew);
-			Optional<TemporalAccessor> now = dateTimeForNow ? touchDate(it, isNew) : Optional.empty();
-
-			if (logger.isDebugEnabled()) {
-
-				Object defaultedNow = now.map(Object::toString).orElse("not set");
-				Object defaultedAuditor = auditor.map(Object::toString).orElse("unknown");
-
-				logger.debug(LogMessage.format("Touched %s - Last modification at %s by %s", target, defaultedNow, defaultedAuditor));
-			}
-
-			return it.getBean();
-
-		}).orElse(target);
-	}
-
-	/**
-	 * Sets modifying and creating auditor. Creating auditor is only set on new auditables.
-	 *
-	 * @param auditable
-	 * @return
-	 */
-	private Optional<Object> touchAuditor(AuditableBeanWrapper<?> wrapper, boolean isNew) {
-
-		Assert.notNull(wrapper, "AuditableBeanWrapper must not be null!");
-
-		return auditorAware.map(it -> {
-
-			Optional<?> auditor = it.getCurrentAuditor();
-
-			Assert.notNull(auditor,
-					() -> String.format("Auditor must not be null! Returned by: %s!", AopUtils.getTargetClass(it)));
-
-			auditor.filter(__ -> isNew).ifPresent(wrapper::setCreatedBy);
-			auditor.filter(__ -> !isNew || modifyOnCreation).ifPresent(wrapper::setLastModifiedBy);
-
-			return auditor;
-		});
-	}
-
-	/**
-	 * Touches the auditable regarding modification and creation date. Creation date is only set on new auditables.
-	 *
-	 * @param wrapper
-	 * @return
-	 */
-	private Optional<TemporalAccessor> touchDate(AuditableBeanWrapper<?> wrapper, boolean isNew) {
-
-		Assert.notNull(wrapper, "AuditableBeanWrapper must not be null!");
-
-		Optional<TemporalAccessor> now = dateTimeProvider.getNow();
-
-		Assert.notNull(now, () -> String.format("Now must not be null! Returned by: %s!", dateTimeProvider.getClass()));
-
-		now.filter(__ -> isNew).ifPresent(wrapper::setCreatedDate);
-		now.filter(__ -> !isNew || modifyOnCreation).ifPresent(wrapper::setLastModifiedDate);
-
-		return now;
+		return markModified(auditorAware.flatMap(AuditorAware::getCurrentAuditor).orElse(null), source);
 	}
 
 	/*
@@ -229,6 +111,8 @@ private Optional<TemporalAccessor> touchDate(AuditableBeanWrapper<?> wrapper, bo
 	 */
 	public void afterPropertiesSet() {
 
+		super.afterPropertiesSet();
+
 		if (!auditorAware.isPresent()) {
 			logger.debug("No AuditorAware set! Auditing will not be applied!");
 		}