spring-projectsgh-4901: introduce ValidatingEntityCallback

Signed-off-by: felgentraeger <[email protected]>

Author: rfelgent

Diff for: spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/event/ValidatingEntityCallback.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2012-2025 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.data.mongodb.core.mapping.event;
+
+import jakarta.validation.ConstraintViolationException;
+import jakarta.validation.Validator;
+import java.util.Set;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.bson.Document;
+import org.springframework.core.Ordered;
+import org.springframework.util.Assert;
+
+/**
+ * javax.validation dependant entities validator.
+ * <p>
+ * When it is registered as Spring component its automatically invoked
+ * after any {@link AbstractMongoEventListener} and before entities are saved in database.
+ *
+ * @author original authors of {@link ValidatingMongoEventListener}
+ * @author Rene Felgenträger
+ *
+ * @see {@link ValidatingMongoEventListener}
+ */
+public class ValidatingEntityCallback implements BeforeSaveCallback<Object>, Ordered {
+
+	private static final Log LOG = LogFactory.getLog(ValidatingEntityCallback.class);
+
+	// TODO: discuss with spring team, if a handler encapsulating validation logic makes more sense (similar to "AuditingHandler")
+	private final Validator validator;
+
+	/**
+	 * Creates a new {@link ValidatingEntityCallback} using the given {@link Validator}.
+	 *
+	 * @param validator must not be {@literal null}.
+	 */
+	public ValidatingEntityCallback(Validator validator) {
+
+		Assert.notNull(validator, "Validator must not be null");
+		this.validator = validator;
+	}
+
+	// TODO: alternatively implement the "BeforeConvertCallback" interface and set the order to highest value ?
+	@Override
+	public Object onBeforeSave(Object entity, Document document, String collection) {
+
+		if (LOG.isDebugEnabled()) {
+			LOG.debug(String.format("Validating object: %s", entity));
+		}
+		Set violations = validator.validate(entity);
+
+		if (!violations.isEmpty()) {
+
+			if (LOG.isDebugEnabled()) {
+				LOG.info(String.format("During object: %s validation violations found: %s", event.getSource(), violations));
+			}
+			throw new ConstraintViolationException(violations);
+		}
+		return entity;
+	}
+
+	@Override
+	public int getOrder() {
+		return 100;
+	}
+}

Diff for: spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/event/ValidatingMongoEventListener.java

@@ -32,6 +32,8 @@
  * @author Maciej Walkowiak
  * @author Oliver Gierke
  * @author Christoph Strobl
+ *
+ * @see {@link ValidatingEntityCallback}
  */
 public class ValidatingMongoEventListener extends AbstractMongoEventListener<Object> {