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update document in mongodb using java -摘自网络

update document in mongodb using java:

Mongodb driver provides functionality to update document in mongodb using java. Update is a process in which single or multiple documents can be updated based on certain criteria. Let us see what javadoc says about update

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<a title="class in com.mongodb.client.result" href="http://api.mongodb.org/java/3.0/com/mongodb/client/result/UpdateResult.html">UpdateResult</a> updateOne(<a title="interface in org.bson.conversions" href="http://api.mongodb.org/java/3.0/org/bson/conversions/Bson.html">Bson</a> filter,

<a title="interface in org.bson.conversions" href="http://api.mongodb.org/java/3.0/org/bson/conversions/Bson.html">Bson</a> update)

Update a single document in the collection according to the specified arguments.

Parameters:
filter – a document describing the query filter, which may not be null.
update – a document describing the update, which may not be null. The update to apply must include only update operators.
Returns:
the result of the update one operation

Let us try to understand with an example. To update document in mongodb using java, consider we have below document in collection.

{

"_id" : ObjectId("55daa2f7e60dd21204306b77"),

"name" : "Harish Taware",

"salary" : 40000,

"type" : "FT"

}

Now we want to update the salary to 80000. We have to provide

A document which will identify above document. Let us say we want to update salary where name is “Harish Taware”
A document which will specify the “$set” operation and the value which will itself be a Document.

Consider below code

Bson filter = new Document("name", "Harish Taware");

Bson newValue = new Document("salary", 90000);

Bson updateOperationDocument = new Document("$set", newValue);

collection.updateOne(filter, updateOperationDocument);

Here,

filter variable stores the document with name Harish Taware
newValue is the document which specifies salary needs to be updated to 90000
updateOperationDocument specifies that a set operation is to be performed.
collection.updateOne(filter,updateOperationDocument) actually does the job of updating document.

Here is complete code

package com.thejavageek.mongodb;

import java.util.ArrayList;

import java.util.List;

import org.bson.Document;

import org.bson.conversions.Bson;

import com.mongodb.MongoClient;

import com.mongodb.client.MongoCollection;

import com.mongodb.client.MongoDatabase;

public class MongodbFind {

public static void main(String[] args) {

MongoClient client = new MongoClient("localhost", 27017);

MongoDatabase database = client.getDatabase("employee_db");

MongoCollection<Document> collection = database

.getCollection("employees");

Bson filter = new Document("name", "Harish Taware");

Bson newValue = new Document("salary", 90000);

Bson updateOperationDocument = new Document("$set", newValue);

collection.updateOne(filter, updateOperationDocument);

client.close();

}

Run the program to update mongodb document using java. Notice the salary is changed

{

"_id" : ObjectId("55daa2f7e60dd21204306b77"),

"name" : "Harish Taware",

"salary" : 90000,

"type" : "FT"

}

Just like updateOne, we have updateMany() method to update multiple documents at once. I hope the article helped understand how to update document in mongodb using java.