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Implementation of connecting to mongodb database using Nodejs

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Release： 2018-06-30 11:48:28

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This article mainly introduces the implementation code of using Nodejs to connect to the mongodb database. Friends who need it can refer to

A simple example of nodejs connecting to mongodb, from the mongodb official example

1. Create package.json

First, create our project directory connect-mongodb and use it as our current directory

mkdir connect-mongodb
cd connect-mongodb

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Enter the npm init command to create package.json

npm init

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Then, install mongodb's nodejs version driver

npm install mongodb --save

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mongodb driver package will be installed into node_modules in the current directory

2 . Start the MongoDB server

Install MongoDB and start the MongoDB database service. Please refer to my previous article, or the official MongoDB documentation

3. Connection MongoDB

Create an app.js file and add the following code to connect to the database named myNewDatabase on the server address 192.168.0.243 and the mongodb port 27017

var MongoClient = require(&#39;mongodb&#39;).MongoClient,
  assert = require(&#39;assert&#39;);
// Connection URL
var url = &#39;mongodb://192.168.0.243:27017/myNewDatabase&#39;;
MongoClient.connect(url,function(err,db){
  assert.equal(null,err);
  console.log("Connection successfully to server");
  db.close();
});

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Enter the following command on the command line to run app.js

node app.js

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4. Insert Documents

Add the following code in app.js and use the insertMany method to add 3 documents to the documents collection

var insertDocuments = function(db, callback){
  // get ths documents collection
  var collection = db.collection(&#39;documents&#39;);
  // insert some documents
  collection.insertMany([
    {a:1},{a:2},{a:3}
  ],function(err,result){
    assert.equal(err,null);
    assert.equal(3,result.result.n);
    assert.equal(3,result.ops.length);
    console.log("Inserted 3 documents into the collection");
    callback(result);
  });
};

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insert command returns an object containing the following attributes:

result Document result returned by MongoDB
ops Document with _id field added
connection The connection used to perform the insert operation

Update the following code in app.js to call the insertDocuments method

var MongoClient = require(&#39;mongodb&#39;).MongoClient
 , assert = require(&#39;assert&#39;);
// Connection URL
var url = &#39;mongodb://localhost:27017/myproject&#39;;
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
 assert.equal(null, err);
 console.log("Connected successfully to server");
 insertDocuments(db, function() {
  db.close();
 });
});

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Use node app.js to run in the command line

5. Query all documents

Add the findDocuments function

var findDocuments = function(db,callback){
  // get the documents collection
  var collection = db.collection(&#39;documents&#39;);
  // find some documents
  collection.find({}).toArray(function(err,docs){
    assert.equal(err,null);
    console.log("Found the following records");
    console.log(docs);
    callback(docs);
  });
};

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The findDocuments function queries all documents in all 'documents' collections and adds this function to the callback function of MongoClient.connect

var MongoClient = require(&#39;mongodb&#39;).MongoClient
 , assert = require(&#39;assert&#39;);
// Connection URL
var url = &#39;mongodb://localhost:27017/myproject&#39;;
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
 assert.equal(null, err);
 console.log("Connected correctly to server");
 insertDocuments(db, function() {
  findDocuments(db, function() {
   db.close();
  });
 });
});

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6. Query documents using query filter

Query 'a' :3’s documentation

var findDocuments = function(db, callback) {
 // Get the documents collection
 var collection = db.collection(&#39;documents&#39;);
 // Find some documents
 collection.find({&#39;a&#39;: 3}).toArray(function(err, docs) {
  assert.equal(err, null);
  console.log("Found the following records");
  console.log(docs);
  callback(docs);
 });   
}

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7. Update documentation

var updateDocument = function(db,callback){
  // get the documents collection
  var collection = db.collection(&#39;documents&#39;);
  // update document where a is 2, set b equal to 1
  collection.updateOne({a:2},{
    $set:{b:1}
  },function(err,result){
    assert.equal(err,null);
    assert.equal(1,result.result.n);
    console.log("updated the document with the field a equal to 2");
    callback(result);
  });
};

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The updateDocument method updates the first document that meets the condition a is 2, adds a b attribute, and sets it to 1.

Add the updateDocument method to the callback of the MongoClient.connect method

MongoClient.connect(url,function(err,db){
  assert.equal(null,err);
  console.log("Connection successfully to server");
  insertDocuments(db,function(){
    updateDocument(db,function(){
      db.close();
    });
  });
});

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8. Delete the document

var removeDocument = function(db,callback){
  // get the documents collection
  var collection = db.collection(&#39;documents&#39;);
  // remove some documents
  collection.deleteOne({a:3},function(err,result){
    assert.equal(err,null);
    assert.equal(1,result.result.n);
    console.log("removed the document with the field a equal to 3");
    callback(result);
  });
};

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Add to app.js

var MongoClient = require(&#39;mongodb&#39;).MongoClient
 , assert = require(&#39;assert&#39;);
// Connection URL
var url = &#39;mongodb://localhost:27017/myproject&#39;;
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
 assert.equal(null, err);
 console.log("Connected successfully to server");
 insertDocuments(db, function() {
  updateDocument(db, function() {
   removeDocument(db, function() {
    db.close();
   });
  });
 });
});

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9. Create indexes

Indexes can improve application performance. Below your code adds an index on the 'a' attribute

var indexCollection = function(db,callback){
  db.collection(&#39;documents&#39;).createIndex({
    a:1
  },null,function(err,results){
    console.log(results);
    callback();
  });
};

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Update app.js

MongoClient.connect(url,function(err,db){
  assert.equal(null,err);
  console.log("Connection successfully to server");
  insertDocuments(db,function(){
    indexCollection(db,function(){
      db.close();
    });
  });
});

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