Node.js mongodb module

Introduction

This example makes use of the mongoDB database (http://www.mongodb.org/)

This example makes use of the Node.js module: mongodb

Please install express using the Node Package Manager

Command: npm install mongodb

Mongo is a module which provides an interface for interacting with a NoSQL Database.

It stores data in a BSON (binary JSON), thus integrates easily with Node.js.

The module itself acts as a namespace rather than a class, meaning most methods are invoked through classes rather than directly from the mongo variable. 


var mongo = require("mongodb");
var config = {//from  w  ww .j a v a  2 s . c o m
  "name": "nodejs-introduction",
  "host": "127.0.0.1",
  //The DEFAULT_PORT attribute is in the Connection class of the mongo namespace
  "port": mongo.Connection.DEFAULT_PORT
};
//Create database and server
console.log("Creating new mongo db with name '" + config.name + "'");
var db = new mongo.Db(config.name, new mongo.Server(config.host, config.port), { w: "majority" });

//Connect to the database
db.open(function(error) {
  if(error) {
    console.log("There was an error connecting to the mongo db: ", error);
  } else {
    console.log("Creating user collection.");
    //Define a database table for storing users
    db.collection("user", function(error, collection) {
      if(error) {
        console.log("There was an error creating the user collection.");
      } else {
        console.log("The user collection was created successfully.");
        //Add users to the collection
        //console.log("Adding users to the user collection...");
        // collection.insert({
        //   "id": "1",
        //   "name": "John Doe",
        //   "email": "jd@example.com"
        // }, function() {
        //   console.log("John Doe inserted into db.");
        // });
        // collection.insert({
        //   "id": "2",
        //   "name": "Jane Doe",
        //   "email": "other_jd@example.com"
        // }, function() {
        //   console.log("Jane Doe inserted into db.");
        // });

        //Get users from collection
        var criteria = { "id":"1" };
        console.log("Querying users matching " + JSON.stringify(criteria) + " from the user collection.");
        collection.find(criteria, function(error, cursor) {
          if(error) {
            console.log("There was an error querying the user collection.");
          } else {
            console.log("successfully queried users from the user collection.")
            cursor.toArray(function(error, results) {
              if(error) {
                console.log("There was an error parsing queried users.");
              } else {
                if(results.length <= 0) {
                  console.log("No users matched the given criteria: " + JSON.stringify(criteria));
                } else {
                  console.log("At least one user found:");
                  console.log(results);
                }
              }
            });
          }
        });
      }
    });
  }
});

console.log("End");



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