Article code (#13567)

persistence-modules/java-mongodb-3/src/main/java/com/baeldung/mongo/insert/InsertFieldIntoFilter.java

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+package com.baeldung.mongo.insert;
+
+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.BsonDocument;
+import org.bson.Document;
+import org.bson.conversions.Bson;
+
+import static com.mongodb.client.model.Filters.*;
+
+public class InsertFieldIntoFilter {
+
+    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 = "pet";
+
+            database = mongoClient.getDatabase(databaseName);
+            collection = database.getCollection(collectionName);
+        }
+    }
+
+    public static void addFieldToExistingBsonFilter() {
+
+        Bson existingFilter = and(eq("type", "Dog"), eq("gender", "Male"));
+
+        Bson newFilter = and(existingFilter, gt("age", 5));
+        FindIterable<Document> documents = collection.find(newFilter);
+
+        MongoCursor<Document> cursor = documents.iterator();
+        while (cursor.hasNext()) {
+            System.out.println(cursor.next());
+        }
+    }
+
+
+    public static void addFieldToExistingBsonFilterUsingBsonDocument() {
+
+        Bson existingFilter = eq("type", "Dog");
+        BsonDocument existingBsonDocument = existingFilter.toBsonDocument(BsonDocument.class, MongoClient.getDefaultCodecRegistry());
+
+        Bson newFilter = gt("age", 5);
+        BsonDocument newBsonDocument = newFilter.toBsonDocument(BsonDocument.class, MongoClient.getDefaultCodecRegistry());
+
+        existingBsonDocument.append("age", newBsonDocument.get("age"));
+
+        FindIterable<Document> documents = collection.find(existingBsonDocument);
+
+        MongoCursor<Document> cursor = documents.iterator();
+        while (cursor.hasNext()) {
+            System.out.println(cursor.next());
+        }
+    }
+
+    public static void main(String args[]) {
+
+        setUp();
+
+        addFieldToExistingBsonFilter();
+
+        addFieldToExistingBsonFilterUsingBsonDocument();
+    }
+}

persistence-modules/java-mongodb-3/src/test/java/com/baeldung/mongo/insert/InsertFieldIntoFilterLiveTest.java

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+package com.baeldung.mongo.insert;
+
+import com.baeldung.mongo.find.FindOperationLiveTest;
+import com.mongodb.MongoClient;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoCursor;
+import com.mongodb.client.MongoDatabase;
+import org.bson.BsonDocument;
+import org.bson.Document;
+import org.bson.conversions.Bson;
+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.*;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public class InsertFieldIntoFilterLiveTest {
+
+    private static MongoClient mongoClient;
+    private static MongoDatabase database;
+    private static MongoCollection<Document> collection;
+    private static final String DATASET_JSON = "/pet.json";
+
+    @BeforeClass
+    public static void setUp() throws IOException {
+        if (mongoClient == null) {
+            mongoClient = new MongoClient("localhost", 27017);
+
+            database = mongoClient.getDatabase("baeldung");
+            collection = database.getCollection("pet");
+
+            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 givenPetCollection_whenFetchingAfterAddingFieldToFilter_thenFindMatchingDocuments() {
+        Bson existingFilter = and(eq("type", "Dog"), eq("gender", "Male"));
+
+        Bson newFilter = and(existingFilter, gt("age", 5));
+        MongoCursor<Document> cursor = collection.find(newFilter).iterator();
+
+        assertNotNull(cursor);
+        assertTrue(cursor.hasNext());
+    }
+
+    @Test
+    public void givenPetCollection_whenFetchingAfterAddingFieldToFilterUsingBsonDocument_thenFindMatchingDocuments() {
+        Bson existingFilter = eq("type", "Dog");
+        BsonDocument existingBsonDocument = existingFilter.toBsonDocument(BsonDocument.class, MongoClient.getDefaultCodecRegistry());
+
+        Bson newFilter = gt("age", 5);
+        BsonDocument newBsonDocument = newFilter.toBsonDocument(BsonDocument.class, MongoClient.getDefaultCodecRegistry());
+
+        existingBsonDocument.append("age", newBsonDocument.get("age"));
+        MongoCursor<Document> cursor = collection.find(existingBsonDocument).iterator();
+
+        assertNotNull(cursor);
+        assertTrue(cursor.hasNext());
+    }
+}

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

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+{"petId":"P1","name":"Tom","age":3,"type":"Cat","gender":"Female"}
+{"petId":"P2","name":"Max","age":4,"type":"Dog","gender":"Male"}
+{"petId":"P3","name":"Milo","age":8,"type":"Dog","gender":"Male"}