#524 - Add example for BeforeConvertCallback.

Closes #524.

mongodb/example/src/main/java/example/springdata/mongodb/immutable/ApplicationConfiguration.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2019 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
+ *
+ *      http://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 example.springdata.mongodb.immutable;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.data.mongodb.core.mapping.event.BeforeConvertCallback;
+
+import com.mongodb.MongoClient;
+
+/**
+ * Test configuration to connect to a MongoDB named "test" and using a {@link MongoClient}. Also enables Spring Data
+ * repositories for MongoDB.
+ *
+ * @author Mark Paluch
+ */
+@SpringBootApplication
+class ApplicationConfiguration {
+
+	/**
+	 * Callback to update {@link ImmutablePerson}.
+	 *
+	 * @return a {@link BeforeConvertCallback} for {@link ImmutablePerson}.
+	 */
+	@Bean
+	BeforeConvertCallback<ImmutablePerson> beforeConvertCallback() {
+
+		return (immutablePerson, collection) -> {
+
+			int randomNumber = ThreadLocalRandom.current().nextInt(1, 100);
+
+			return immutablePerson.withRandomNumber(randomNumber);
+		};
+	}
+
+}

mongodb/example/src/main/java/example/springdata/mongodb/immutable/ImmutablePerson.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2019 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
+ *
+ *      http://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 example.springdata.mongodb.immutable;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import lombok.experimental.Wither;
+
+import org.bson.types.ObjectId;
+
+/**
+ * Immutable object.
+ *
+ * @author Mark Paluch
+ */
+@Wither
+@Getter
+@RequiredArgsConstructor
+public class ImmutablePerson {
+
+	private final ObjectId id;
+
+	private final int randomNumber;
+
+	public ImmutablePerson() {
+		this(null, 0);
+	}
+}

mongodb/example/src/test/java/example/springdata/mongodb/immutable/ImmutableEntityIntegrationTest.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2019 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
+ *
+ *      http://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 example.springdata.mongodb.immutable;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.data.mongodb.core.MongoOperations;
+import org.springframework.test.context.junit4.SpringRunner;
+
+/**
+ * Integration test for {@link ImmutablePerson} showing features around immutable object support.
+ *
+ * @author Mark Paluch
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class ImmutableEntityIntegrationTest {
+
+	@Autowired MongoOperations operations;
+
+	@Before
+	public void setUp() {
+
+		operations.remove(ImmutablePerson.class);
+	}
+
+	/**
+	 * Test case to show that automatically generated ids are assigned to the immutable domain object and how the
+	 * {@link ImmutablePerson#getRandomNumber()} gets set via {@link ApplicationConfiguration#beforeConvertCallback()}.
+	 */
+	@Test
+	public void setsRandomNumberOnSave() {
+
+		ImmutablePerson unsaved = new ImmutablePerson();
+		assertThat(unsaved.getRandomNumber()).isZero();
+
+		ImmutablePerson saved = operations.save(unsaved);
+
+		assertThat(saved.getId()).isNotNull();
+		assertThat(saved.getRandomNumber()).isNotZero();
+	}
+}