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Thomas Darimontodrotbohm
Thomas Darimont
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odrotbohm
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spring-projects#54 - Added a project for MongoDB examples using Java 8 features.
This initial version of the example projects demonstrates the usage and mapping behavior of Java 8 Streams in repositories. The test cases oppose a plain List based query method with one that uses a Stream and shows how the former pulls all data into memory first and the iteration is done over the pre-populated list. The execution of the Stream based method in contrast shows that the individual elements are read and converted while iterating the stream.
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‎mongodb/java8/README.md‎

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# Spring Data MongoDB - Java 8 examples
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This project contains samples of Java 8 specific features of Spring Data (MongoDB).
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## Support for JDK 8's `Stream` for repository methods
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Repository methods can use a Java 8 `Stream` as a return type which will cause the reading of the results and the to-object-conversion of the `DBObject` to happen while iterating over the stream.
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```java
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public interface PersonRepository extends CrudRepository<Person, String> {
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@Override
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List<Person> findAll();
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//Custom Query method returning a Java 8 Stream
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@Query("{}")
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Stream<Person> findAllByCustomQueryWithStream();
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}
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```
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The test cases in `PersonRepositoryIntegrationTest` oppose a plain `List` based query method with one that uses a `Stream` and shows how the former pulls all data into memory first and the iteration is done over the pre-populated list. The execution of the `Stream`-based method in contrast shows that the individual elements are read and converted while iterating the stream.

‎mongodb/java8/pom.xml‎

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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>org.springframework.data.examples</groupId>
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<artifactId>spring-data-mongodb-examples</artifactId>
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<version>1.0.0.BUILD-SNAPSHOT</version>
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</parent>
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<artifactId>spring-data-mongodb-java8</artifactId>
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<name>Spring Data MongoDB - Java 8 specific features</name>
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<properties>
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<spring-data-releasetrain.version>Fowler-BUILD-SNAPSHOT</spring-data-releasetrain.version>
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</properties>
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<dependencies>
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<dependency>
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<groupId>${project.groupId}</groupId>
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<artifactId>spring-data-mongodb-utils</artifactId>
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<version>${project.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>org.springframework.data</groupId>
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<artifactId>spring-data-mongodb</artifactId>
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</dependency>
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</dependencies>
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</project>

‎mongodb/java8/src/main/java/example/springdata/mongodb/people/ApplicationConfiguration.java‎

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/*
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* Copyright 2015 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package example.springdata.mongodb.people;
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import org.springframework.boot.autoconfigure.SpringBootApplication;
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import org.springframework.context.annotation.Bean;
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import org.springframework.data.mongodb.core.mapping.event.LoggingEventListener;
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/**
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* Simple configuration that registers a {@link LoggingEventListener} to demonstrate mapping behaviour when Java 8
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* Streams are used.
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*
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* @author Thomas Darimont
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*/
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@SpringBootApplication
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class ApplicationConfiguration {
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public @Bean LoggingEventListener mongoEventListener() {
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return new LoggingEventListener();
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}
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}

‎mongodb/java8/src/main/java/example/springdata/mongodb/people/Person.java‎

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/*
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* Copyright 2015 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package example.springdata.mongodb.people;
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import lombok.Data;
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import lombok.RequiredArgsConstructor;
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import org.springframework.data.annotation.Id;
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/**
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* An entity to represent a Person.
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*
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* @author Thomas Darimont
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*/
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@Data
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@RequiredArgsConstructor
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public class Person {
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private @Id String id;
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private final String firstname;
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private final String lastname;
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}

‎mongodb/java8/src/main/java/example/springdata/mongodb/people/PersonRepository.java‎

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/*
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* Copyright 2015 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package example.springdata.mongodb.people;
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import java.util.List;
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import java.util.stream.Stream;
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import org.springframework.data.mongodb.repository.Query;
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import org.springframework.data.repository.CrudRepository;
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/**
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* Repository interface to manage {@link Person} instances.
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*
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* @author Thomas Darimont
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*/
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public interface PersonRepository extends CrudRepository<Person, String> {
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List<Person> findAll();
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@Query("{}")
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Stream<Person> findAllByCustomQueryWithStream();
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}

‎mongodb/java8/src/test/java/example/springdata/mongodb/people/PersonRepositoryIntegrationTest.java‎

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/*
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* Copyright 2015 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package example.springdata.mongodb.people;
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import org.junit.Before;
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import org.junit.ClassRule;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.boot.test.SpringApplicationConfiguration;
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import org.springframework.data.mongodb.core.MongoOperations;
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import org.springframework.data.mongodb.core.mapping.event.LoggingEventListener;
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import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
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import example.springdata.mongodb.util.RequiresMongoDB;
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/**
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* Integration test for {@link PersonRepository}.
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*
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* @author Thomas Darimont
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*/
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@RunWith(SpringJUnit4ClassRunner.class)
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@SpringApplicationConfiguration(classes = ApplicationConfiguration.class)
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public class PersonRepositoryIntegrationTest {
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@ClassRule public static RequiresMongoDB mongodbAvailable = RequiresMongoDB.anyVersion();
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@Autowired PersonRepository repository;
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@Autowired MongoOperations operations;
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Person dave, oliver, carter;
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@Before
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public void setUp() {
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repository.deleteAll();
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dave = repository.save(new Person("Dave", "Matthews"));
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oliver = repository.save(new Person("Oliver August", "Matthews"));
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carter = repository.save(new Person("Carter", "Beauford"));
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}
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/**
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* Note that the all object conversions are preformed before the results are printed to the console.
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*/
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@Test
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public void shouldPerformConversionBeforeResultProcessing() {
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repository.findAll().forEach(System.out::println);
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}
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/**
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* Note that the object conversions are preformed during stream processing as one can see from the
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* {@link LoggingEventListener} output that is printed to the console.
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*/
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@Test
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public void shouldPerformConversionDuringJava8StreamProcessing() {
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repository.findAllByCustomQueryWithStream().forEach(System.out::println);
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}
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}

‎mongodb/java8/src/test/java/example/springdata/mongodb/people/package-info.java‎

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/**
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* Package showing usage of Spring Data MongoDB Repositories with Java 8.
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*/
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package example.springdata.mongodb.people;
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‎mongodb/pom.xml‎

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<name>Spring Data MongoDB - Examples</name>
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<description>Sample projects for Spring Data MongoDB</description>
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<url>http://projects.spring.io/spring-data-mongodb</url>
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<inceptionYear>2011-2014</inceptionYear>
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<inceptionYear>2011-2015</inceptionYear>
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<modules>
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<module>aggregation</module>
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<module>example</module>
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<module>text-search</module>
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<module>java8</module>
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<module>util</module>
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</modules>
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