Java MongoDB : Update document

In this tutorial, we show you how to use Java MongoDB API

collection.update()

to update documents.

Test Data

Assume following data/documents are inserted.

{
"hosting" : "hostA",
"type" : "vps",
"clients" : 1000
},
{
"hosting" : "hostB",
"type" : "dedicated server",
"clients" : 100
},
{
"hosting" : "hostC",
"type" : "vps",
"clients" : 900
}

{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 100}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

1.

DBCollection.update()

with

$set

Find document where

hosting = ‘hostB’

, and update it’s clients values from 100 to 110.

BasicDBObject newDocument = new BasicDBObject();
newDocument.put("clients", 110);

BasicDBObject searchQuery = new BasicDBObject().append("hosting", "hostB");

collection.update(searchQuery, newDocument);

Output

{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{ "_id" : { "$oid" : "id"} , "clients" : 110}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

The document is replaced!?

Wait, the entire “

hostB

” document is replaced with another new document, this is not what we want.

To update a particular value only, uses

$set

update modifier.

BasicDBObject newDocument = new BasicDBObject();
newDocument.append("$set", new BasicDBObject().append("clients", 110));

BasicDBObject searchQuery = new BasicDBObject().append("hosting", "hostB");

collection.update(searchQuery, newDocument);

Output

{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 110}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

Note

The MongoDB team should create another new API named

DBCollection.replace()

, many beginners are trapped in this

DBCollection.update()

API and replace the entire document accidentally. Again, to update a particular value, use

$set

.

2.

DBCollection.update()

with

$inc

This example show the use of

$inc

modifier to increase a particular value. Find document where

hosting = ‘hostB’

, update it’s ‘

clients

’ value by increasing the value from 100 to 199, (100 + 99) = 199.

BasicDBObject newDocument =
new BasicDBObject().append("$inc",
new BasicDBObject().append("total clients", 99));

collection.update(new BasicDBObject().append("hosting", "hostB"), newDocument);

Output

{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 199}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

3.

DBCollection.update()

with

multi

This example show the use of

multi

parameter to update a set of matched documents. Find document where

type = ‘vps’

, update all the matched documents’ ‘

clients

’ value to 888.

BasicDBObject updateQuery = new BasicDBObject();
updateQuery.append("$set",
new BasicDBObject().append("clients", "888"));

BasicDBObject searchQuery = new BasicDBObject();
searchQuery.append("type", "vps");

collection.updateMulti(searchQuery, updateQuery);

//below statement set multi to true.
//collection.update(searchQuery, updateQuery, false, true);

Output

{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "clients" : "888" , "type" : "vps"}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 100}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "clients" : "888" , "type" : "vps"}

Note

If update without the multi set to true.

BasicDBObject updateQuery = new BasicDBObject();
updateQuery.append("$set",
new BasicDBObject().append("clients", "888"));

BasicDBObject searchQuery = new BasicDBObject();
searchQuery.append("type", "vps");

collection.update(searchQuery, updateQuery);

You will noticed that only the first matched document is updated.

{"_id":{ "$oid" : "x"} , "hosting" : "hostA" , "clients" : "888" , "type" : "vps"}
{"_id":{ "$oid" : "x"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 100}
{"_id":{ "$oid" : "x"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

To update a set of matched documents, you need to set “

multi

” to

true

.

4. Full Example

Full example by combining above code snippets.

package com.mkyong.core;

import java.net.UnknownHostException;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.Mongo;
import com.mongodb.MongoException;

/**
* Java MongoDB update document
*
* @author mkyong
*
*/

public class UpdateApp {

public static void printAllDocuments(DBCollection collection) {
DBCursor cursor = collection.find();
while (cursor.hasNext()) {
System.out.println(cursor.next());
}
}

public static void removeAllDocuments(DBCollection collection) {
collection.remove(new BasicDBObject());
}

public static void insertDummyDocuments(DBCollection collection) {
BasicDBObject document = new BasicDBObject();
document.put("hosting", "hostA");
document.put("type", "vps");
document.put("clients", 1000);

BasicDBObject document2 = new BasicDBObject();
document2.put("hosting", "hostB");
document2.put("type", "dedicated server");
document2.put("clients", 100);

BasicDBObject document3 = new BasicDBObject();
document3.put("hosting", "hostC");
document3.put("type", "vps");
document3.put("clients", 900);

collection.insert(document);
collection.insert(document2);
collection.insert(document3);
}

public static void main(String[] args) {

try {

Mongo mongo = new Mongo("localhost", 27017);
DB db = mongo.getDB("yourdb");

// get a single collection
DBCollection collection = db.getCollection("dummyColl");

System.out.println("Testing 1...no $set");

insertDummyDocuments(collection);

// find hosting = hostB, and update the clients to 110
BasicDBObject newDocument = new BasicDBObject();
newDocument.put("clients", 110);

BasicDBObject searchQuery = new BasicDBObject().append("hosting", "hostB");

collection.update(searchQuery, newDocument);

printAllDocuments(collection);
removeAllDocuments(collection);

System.out.println("\nTesting 1...with $set");

insertDummyDocuments(collection);

BasicDBObject updateDocument = new BasicDBObject();
updateDocument.append("$set", new BasicDBObject().append("clients", 110));

BasicDBObject searchQuery2 = new BasicDBObject().append("hosting", "hostB");

collection.update(searchQuery2, updateDocument);

printAllDocuments(collection);
removeAllDocuments(collection);

System.out.println("\nTesting 2... with $inc");
insertDummyDocuments(collection);
// find hosting = hostB and increase it's "clients" value by 99
BasicDBObject newDocument2 = new BasicDBObject().append("$inc",
new BasicDBObject().append("clients", 99));

collection.update(new BasicDBObject().append("hosting", "hostB"), newDocument2);

printAllDocuments(collection);
removeAllDocuments(collection);

System.out.println("\nTesting 3... with $multi");

insertDummyDocuments(collection);
// find type = vps , update all matched documents , clients value to 888
BasicDBObject updateQuery = new BasicDBObject();
updateQuery.append("$set", new BasicDBObject().append("clients", "888"));

BasicDBObject searchQuery3 = new BasicDBObject();
searchQuery3.append("type", "vps");

collection.updateMulti(searchQuery3, updateQuery);
// collection.update(searchQuery3, updateQuery, false, true);

printAllDocuments(collection);
removeAllDocuments(collection);

System.out.println("Done");

} catch (UnknownHostException e) {
e.printStackTrace();
} catch (MongoException e) {
e.printStackTrace();
}

}
}

Output

Testing 1...no $set
{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{ "_id" : { "$oid" : "id"} , "clients" : 110}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

Testing 1...with $set{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 110}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

Testing 2... with $inc
{ "_id" : { "$oid" : "id"} , "hosting" : "hostA" , "type" : "vps" , "clients" : 1000}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 199}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}

Testing 3... with $multi
{ "_id" : { "$oid" : "id"} , "hosting" : "hostB" , "type" : "dedicated server" , "clients" : 100}
{ "_id" : { "$oid" : "id"} , "hosting" : "hostC" , "type" : "vps" , "clients" : 900}
{ "_id" : { "$oid" : "id"} , "clients" : "888" , "hosting" : "hostA" , "type" : "vps"}

Done