MongoDB學習（2）—Node.js與MongoDB的基本串連樣本

標籤：

前提

已經安裝了node.js和MongoDB，本文使用的node.js是v0.12.0，MongoDB是3.0.0。

初始化資料

啟動MongoDB服務，在test資料庫中插入一條執行個體資料：

db.user.install({name:"scaleworld",age:27});

在Node.js中引入MongoDB模組

npm install mongodb

編寫mongodbDemo.js

var mongodb = require(‘mongodb‘);var server = new mongodb.Server("localhost",27017,{safe:true});new mongodb.Db(‘test‘,server,{}).open(function(error,client){    if(error) throw error;    var collection = new mongodb.Collection(client,‘user‘);    collection.find(function(error,cursor){        cursor.each(function(error,doc){            if(doc){                console.log("name:"+doc.name+" age:"+doc.age);            }        });    });});

運行

{ [Error: Cannot find module ‘../build/Release/bson‘] code: ‘MODULE_NOT_FOUND‘ }js-bson: Failed to load c++ bson extension, using pure JS version================================================================================Please ensure that you set the default write concern for the database by setting    ==   one of the options                                                                 ==                                                                                      ==     w: (value of > -1 or the string ‘majority‘), where < 1 means                     ==        no write acknowlegement                                                       ==     journal: true/false, wait for flush to journal before acknowlegement             ==     fsync: true/false, wait for flush to file system before acknowlegement           ==                                                                                      ==  For backward compatibility safe is still supported and                              ==   allows values of [true | false | {j:true} | {w:n, wtimeout:n} | {fsync:true}]      ==   the default value is false which means the driver receives does not                ==   return the information of the success/error of the insert/update/remove            ==                                                                                      ==   ex: new Db(new Server(‘localhost‘, 27017), {safe:false})                           ==                                                                                      ==   http://www.mongodb.org/display/DOCS/getLastError+Command                           ==                                                                                      ==  The default of no acknowlegement will change in the very near future                ==                                                                                      ==  This message will disappear when the default safe is set on the driver Db           =========================================================================================name:scaleworld age:27

雖然最後列印出了我們之前插入的資料，但是前面一大串的錯誤還是人看著不舒服，我們要消滅它們。

Error: Cannot find module ‘../build/Release/bson‘的解決辦法

{ [Error: Cannot find module ‘../build/Release/bson‘] code: ‘MODULE_NOT_FOUND‘ }js-bson: Failed to load c++ bson extension, using pure JS version

頭兩行說的是沒有發現bson模組。好辦我們立馬安裝：

npm install bson

然後將D:\nodejsdemo\node_modules\mongodb\node_modules\bson\ext\index.js中的bson = require(‘../build/Release/bson‘)改成bson = require(‘bson‘) ，重新運行。

不過這樣只是解決頭兩行的問題，還有用=包圍起來的問題。

“Please ensure that you set the default write concern for the database”的解決辦法

從最後一句話“This message will disappear when the default safe is set on the driver Db”我們就可以看出該問題的解決辦法，只要將資料庫連接設定為安全即可。

具體代碼修改如下：

new mongodb.Db(‘test‘,server,{})修改為new mongodb.Db(‘test‘,server,{safe:true})

 

MongoDB學習（2）—Node.js與MongoDB的基本串連樣本