[BAEL-5355] code snippets for article - lukaswlodkowski (#12954)

* [BAEL-5355] code snippets for article

* [BAEL-5355] fix tests naming convention

* [BAEL-5355] try different Mongo configuration, previous one failed on Jenkins.

* [BAEL-5355] try different Mongo configuration, previous one failed on Jenkins.

* [BAEL-5355] try different Mongo configuration, previous one failed on Jenkins.

persistence-modules/spring-data-mongodb-2/src/main/java/com/baeldung/objectId/User.java

@@ -0,0 +1,24 @@
+package com.baeldung.objectId;
+
+import org.bson.types.ObjectId;
+
+public class User {
+    public static final String NAME_FIELD = "name";
+
+    private final ObjectId id;
+    private final String name;
+
+    public User(ObjectId id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public ObjectId getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+}
+

persistence-modules/spring-data-mongodb-2/src/test/java/com/baeldung/objectId/SameObjectIdUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.objectId;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.nio.ByteBuffer;
+import java.util.Date;
+
+import org.bson.types.ObjectId;
+import org.junit.jupiter.api.Test;
+
+public class SameObjectIdUnitTest {
+
+    @Test
+    public void givenSameDateAndCounter_whenComparingObjectIds_thenTheyAreNotEqual() {
+        final Date date = new Date();
+        final ObjectId objectIdDate = new ObjectId(date);
+        final ObjectId objectIdDateCounter1 = new ObjectId(date, 100);
+        final ObjectId objectIdDateCounter2 = new ObjectId(date, 100);
+
+        assertThat(objectIdDate).isNotEqualTo(objectIdDateCounter1);
+        assertThat(objectIdDate).isNotEqualTo(objectIdDateCounter2);
+
+        assertThat(objectIdDateCounter1).isEqualTo(objectIdDateCounter2);
+    }
+
+    @Test
+    public void givenSameArrayOfBytes_whenComparingObjectIdsCreatedViaDifferentMethods_thenTheObjectIdsAreEqual() {
+        final byte[] bytes = "123456789012".getBytes();
+        final ObjectId objectIdBytes = new ObjectId(bytes);
+
+        final ByteBuffer buffer = ByteBuffer.wrap(bytes);
+        final ObjectId objectIdByteBuffer = new ObjectId(buffer);
+
+        assertThat(objectIdBytes).isEqualTo(objectIdByteBuffer);
+    }
+}

persistence-modules/spring-data-mongodb-2/src/test/java/com/baeldung/objectId/SameObjectIdUsedToInsertSameObjectIdUnitTest.java

@@ -0,0 +1,60 @@
+package com.baeldung.objectId;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.List;
+
+import org.assertj.core.util.Lists;
+import org.bson.types.ObjectId;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.dao.DuplicateKeyException;
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+import com.baeldung.objectId.config.MongoConfig;
+
+@ExtendWith(SpringExtension.class)
+@ContextConfiguration(classes = MongoConfig.class)
+public class SameObjectIdUsedToInsertSameObjectIdUnitTest {
+    @Autowired
+    private MongoTemplate mongoTemplate;
+
+    @BeforeEach
+    public void setUp() {
+        mongoTemplate.dropCollection(User.class);
+    }
+
+    @Test
+    public void givenUserInDatabase_whenInsertingAnotherUserWithTheSameObjectId_DKEThrownAndInsertRetried() {
+        //given
+        final String userName = "Kevin";
+        final User firstUser = new User(ObjectId.get(), userName);
+        final User secondUser = new User(ObjectId.get(), userName);
+
+        mongoTemplate.insert(firstUser);
+
+        //when
+        try {
+            mongoTemplate.insert(firstUser);
+        } catch (DuplicateKeyException dke) {
+            mongoTemplate.insert(secondUser);
+        }
+
+        //then
+        final Query query = new Query();
+        query.addCriteria(Criteria.where(User.NAME_FIELD)
+          .is(userName));
+        final List<User> users = mongoTemplate.find(query, User.class);
+
+        assertThat(users).usingRecursiveComparison()
+          .isEqualTo(Lists.newArrayList(firstUser, secondUser));
+    }
+}
+
+

persistence-modules/spring-data-mongodb-2/src/test/java/com/baeldung/objectId/config/MongoConfig.java

@@ -0,0 +1,42 @@
+package com.baeldung.objectId.config;
+
+import org.bson.UuidRepresentation;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.util.SocketUtils;
+
+import com.mongodb.ConnectionString;
+import com.mongodb.MongoClientSettings;
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+
+import de.flapdoodle.embed.mongo.MongodExecutable;
+import de.flapdoodle.embed.mongo.MongodStarter;
+import de.flapdoodle.embed.mongo.config.ImmutableMongodConfig;
+import de.flapdoodle.embed.mongo.config.MongodConfig;
+import de.flapdoodle.embed.mongo.config.Net;
+import de.flapdoodle.embed.mongo.distribution.Version;
+import de.flapdoodle.embed.process.runtime.Network;
+
+@Configuration
+public class MongoConfig {
+    private static final String CONNECTION_STRING = "mongodb://%s:%d";
+    private static final String HOST = "localhost";
+
+    @Bean
+    public MongoTemplate mongoTemplate() throws Exception {
+        int randomPort = SocketUtils.findAvailableTcpPort();
+
+        ImmutableMongodConfig mongoDbConfig = MongodConfig.builder()
+          .version(Version.Main.PRODUCTION)
+          .net(new Net(HOST, randomPort, Network.localhostIsIPv6()))
+          .build();
+
+        MongodStarter starter = MongodStarter.getDefaultInstance();
+        MongodExecutable mongodExecutable = starter.prepare(mongoDbConfig);
+        mongodExecutable.start();
+
+        return new MongoTemplate(MongoClients.create(String.format(CONNECTION_STRING, HOST, randomPort)), "mongo_auth");
+    }
+}