MongoDB Documentation: Document Update

MongoDB Documentation

MongoDB Documentation – There are several methods to update Document in MongoDB:

• updateOne: refreshes one document that meets the filtering criteria and returns information about the update operation
• updateMany: refreshes all documents that meet the filtering criteria and returns information about the update operation
• findOneAndUpdate: refreshes one document that meets the filter criteria and returns an updated document.

findOneAndUpdate

The findOneAndUpdate() method updates one element. It accepts the following parameters:

• The criterion for filtering the document to be updated
• Update option
• Additional update options, which are null by default
• The callback function that is performed during an update

For example, let’s update the first user in the database who is 21 years old:

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017/";
const mongoClient = new MongoClient(url, { useNewUrlParser: true });

let users = [{name: "Bob", age: 34} , {name: "Alice", age: 21}, {name: "Tom", age: 45}];
mongoClient.connect(function(err, client){

if(err) return console.log(err);

const db = client.db("usersdb");
const col = db.collection("usersdb");
col.insertMany(users, function(err, results){

col.findOneAndUpdate(
{age: 21}, // sampling criterion
{$set: {age: 25}}, // update parameter
function(err, result){

console.log(result);
client.close();
}
);
});
});

At first, 3 users shall be added to the database, and after the addition is updated.

The object { $set shall be used for updating: object {age: 25}}. The $set parameter shall update the values for a single field or group of fields. In this case, the age field shall be changed.

The third parameter, the callback function, displays the update result. By default, this is the old state of the modified document:

But, let’s say, after the update, we want to get not the old but the new state of the modified document. To do this, we can specify additional update options.

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017/";
const mongoClient = new MongoClient(url, { useNewUrlParser: true });

mongoClient.connect(function(err, client){

if(err) return console.log(err);

const db = client.db("usersdb");
const col = db.collection("usersdb");
col.findOneAndUpdate(
{name: "Bob"}, // sampling criterion
{$set: {name: "Sam"}}, // update parameter
{ // additional update options
returnOriginal: false
},
function(err, result){

console.log(result);
client.close();
}
);
});

updateMany

The updateMany() method allows you to update all documents in the collection that meet the filtering criteria:

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017/";
const mongoClient = new MongoClient(url, { useNewUrlParser: true });

mongoClient.connect(function(err, client){

if(err) return console.log(err);

const db = client.db("usersdb");
const col = db.collection("usersdb");
col.updateMany(
{name: "Sam"}, // filter criterion
{$set: {name: "Bob"}}, // update parameter
function(err, result){

console.log(result);
client.close();
}
);
});

updateOne

The updateOne() method is similar to the updateMany method except that it updates only one element. Unlike the findOneAndUpdate() method, it does not return a modified document:

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017/";
const mongoClient = new MongoClient(url, { useNewUrlParser: true });

mongoClient.connect(function(err, client){

if(err) return console.log(err);

const db = client.db("usersdb");
const col = db.collection("usersdb");
col.updateOne(
{name: "Tom"},
{$set: {name: "Tom Junior", age:33}},
function(err, result){

console.log(result);
client.close();
}
);
});

Database, Collections, Documents: MongoDB

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