BAEL-5368 Guide to Find in MongoDB (#12361)

* BAEL-5368 | Article code

* BAEL-5368 | Package renamed

persistence-modules/java-mongodb-3/.gitignore

@@ -0,0 +1,5 @@
+.classpath
+.project
+.settings
+target
+build

persistence-modules/java-mongodb-3/pom.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>java-mongodb-3</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>java-mongodb-3</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>persistence-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.mongodb</groupId>
+            <artifactId>mongo-java-driver</artifactId>
+            <version>${mongo.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <mongo.version>3.12.1</mongo.version>
+    </properties>
+
+</project>

persistence-modules/java-mongodb-3/src/main/java/com/baeldung/mongo/find/FindOperation.java

@@ -0,0 +1,86 @@
+package com.baeldung.mongo.find;
+
+import com.mongodb.MongoClient;
+import com.mongodb.client.FindIterable;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoCursor;
+import com.mongodb.client.MongoDatabase;
+import org.bson.Document;
+import org.bson.conversions.Bson;
+
+import static com.mongodb.client.model.Filters.eq;
+import static com.mongodb.client.model.Projections.fields;
+import static com.mongodb.client.model.Projections.include;
+
+public class FindOperation {
+
+    private static MongoClient mongoClient;
+    private static MongoDatabase database;
+    private static MongoCollection<Document> collection;
+    private static String collectionName;
+    private static String databaseName;
+
+    public static void setUp() {
+        if (mongoClient == null) {
+            mongoClient = new MongoClient("localhost", 27017);
+
+            databaseName = "baeldung";
+            collectionName = "employee";
+
+            database = mongoClient.getDatabase(databaseName);
+            collection = database.getCollection(collectionName);
+        }
+    }
+
+    public static void retrieveAllDocumentsUsingFind() {
+        FindIterable<Document> documents = collection.find();
+
+        MongoCursor<Document> cursor = documents.iterator();
+        while (cursor.hasNext()) {
+            System.out.println(cursor.next());
+        }
+    }
+
+    public static void retrieveAllDocumentsUsingFindWithQueryFilter() {
+        Bson filter = eq("department", "Engineering");
+        FindIterable<Document> documents = collection.find(filter);
+
+        MongoCursor<Document> cursor = documents.iterator();
+        while (cursor.hasNext()) {
+            System.out.println(cursor.next());
+        }
+    }
+
+    public static void retrieveAllDocumentsUsingFindWithQueryFilterAndProjection() {
+        Bson filter = eq("department", "Engineering");
+        Bson projection = fields(include("name", "age"));
+        FindIterable<Document> documents = collection.find(filter)
+          .projection(projection);
+
+        MongoCursor<Document> cursor = documents.iterator();
+        while (cursor.hasNext()) {
+            System.out.println(cursor.next());
+        }
+    }
+
+    public static void retrieveFirstDocument() {
+        FindIterable<Document> documents = collection.find();
+        Document document = documents.first();
+
+        System.out.println(document);
+    }
+
+    public static void main(String args[]) {
+
+        setUp();
+
+        retrieveAllDocumentsUsingFind();
+
+        retrieveAllDocumentsUsingFindWithQueryFilter();
+
+        retrieveAllDocumentsUsingFindWithQueryFilterAndProjection();
+
+        retrieveFirstDocument();
+    }
+}
+

persistence-modules/java-mongodb-3/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

persistence-modules/java-mongodb-3/src/test/java/com/baeldung/mongo/find/FindOperationLiveTest.java

@@ -0,0 +1,94 @@
+package com.baeldung.mongo.find;
+
+import com.mongodb.MongoClient;
+import com.mongodb.client.FindIterable;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoCursor;
+import com.mongodb.client.MongoDatabase;
+import org.bson.Document;
+import org.bson.conversions.Bson;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+
+import static com.mongodb.client.model.Filters.eq;
+import static com.mongodb.client.model.Projections.fields;
+import static com.mongodb.client.model.Projections.include;
+import static org.junit.Assert.*;
+
+public class FindOperationLiveTest {
+
+    private static MongoClient mongoClient;
+    private static MongoDatabase database;
+    private static MongoCollection<Document> collection;
+    private static final String DATASET_JSON = "/employee.json";
+
+    @BeforeClass
+    public static void setUp() throws IOException {
+        if (mongoClient == null) {
+            mongoClient = new MongoClient("localhost", 27017);
+
+            database = mongoClient.getDatabase("baeldung");
+            collection = database.getCollection("employee");
+
+            collection.drop();
+
+            InputStream is = FindOperationLiveTest.class.getResourceAsStream(DATASET_JSON);
+            BufferedReader reader = new BufferedReader(new InputStreamReader(is));
+            reader.lines()
+              .forEach(line -> collection.insertOne(Document.parse(line)));
+            reader.close();
+        }
+    }
+
+    @Test
+    public void givenEmployeeCollection_whenFetchingUsingFindOperations_thenCheckingForDocuments() {
+        FindIterable<Document> documents = collection.find();
+        MongoCursor<Document> cursor = documents.iterator();
+
+        assertNotNull(cursor);
+        assertTrue(cursor.hasNext());
+    }
+
+    @Test
+    public void givenEmployeeCollection_whenFetchingUsingFindOperationsWithFilters_thenCheckingForDocuments() {
+        Bson filter = eq("department", "Engineering");
+        FindIterable<Document> documents = collection.find(filter);
+        MongoCursor<Document> cursor = documents.iterator();
+
+        assertNotNull(cursor);
+        assertTrue(cursor.hasNext());
+    }
+
+    @Test
+    public void givenEmployeeCollection_whenFetchingUsingFindOperationsWithFiltersAndProjection_thenCheckingForDocuments() {
+        Bson filter = eq("department", "Engineering");
+        Bson projection = fields(include("name", "age"));
+        FindIterable<Document> documents = collection.find(filter)
+          .projection(projection);
+        MongoCursor<Document> cursor = documents.iterator();
+
+        assertNotNull(cursor);
+        assertTrue(cursor.hasNext());
+    }
+
+    @Test
+    public void givenEmployeeCollection_whenFetchingFirstDocumentUsingFindOperations_thenCheckingForDocument() {
+        Document employee = collection.find()
+          .first();
+
+        assertNotNull(employee);
+        assertFalse(employee.isEmpty());
+    }
+
+    @AfterClass
+    public static void cleanUp() {
+        mongoClient.close();
+    }
+}
+

persistence-modules/java-mongodb-3/src/test/resources/employee.json

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+{"employeeId":"EMP1","name":"Sam","age":23,"type":"Full Time","department":"Engineering"}
+{"employeeId":"EMP2","name":"Tony","age":31,"type":"Full Time","department":"Admin"}
+{"employeeId":"EMP3","name":"Lisa","age":42,"type":"Part Time","department":"Engineering"}

persistence-modules/pom.xml

@@ -44,6 +44,7 @@
         <module>java-jpa-3</module>
         <module>java-mongodb</module> <!-- long running -->
         <module>java-mongodb-2</module> <!-- long running -->
+        <module>java-mongodb-3</module> <!-- long running -->
         <module>jnosql</module> <!-- long running -->
         <module>jooq</module>
         <module>jpa-hibernate-cascade-type</module>