Shulou(Shulou.com)06/01 Report--

NodeJs connects to the mongodb database and generates the corresponding URL according to the server, so write a method:

Var createURL = function () {var mongourl = ""; if (process.env.VCAP_SERVICES) {mongourl =.;} else {mongourl =.;} console.log ("config database url..."); return mongourl;} exports.url = createURL ()

To connect to the database in the model layer, you only need to call the modification method directly.

First add a reference:

Var urlFactory = require ('. / dbFactory')

Then, call directly:

Require ('mongodb') .connect (urlFactory.url, function (err, conn) {/ / read users collection conn.collection (' users', function (err, collection) {/ / do something});})

In this way, all the places where you need to connect to the database, you need to call the urlFactory.url, that is, the createURL method, which is definitely inefficient. So, I was going to write a cache or something and save the url temporarily so that I don't have to rejudge and regenerate it every time.

However, an inexplicable problem arises. No matter how you run the system, console.log ("config database url..."); output only once!

Why is that? The mechanism of NodeJs? Or is it exports? My guess is require ('mongodb'). Connect (urlFactory.url, fn); this kind of link is similar to session.

Write down a note here and study it later.

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