Hello, everyone!
I am new to Node.Js and not very well understanding the mecanics of
callbacks.
I have a MongoDB database installed and running. I have a 'users'
collection. In my Node.js (Express) application I want to display a list of
stored users.
I am doing the following experiment:
var express = require('express');
var router = express.Router();
var userRepository = require('../repositories/user_repository.js');
router.get('/:long?', function(req, res) {
var long = req.param('long');
long = !!long;
userRepository.getAllUsers(function(users) {
res.render('index', {
users: users
});
}, long);
});
It's a handler for my http://website.com/ URL, which may have an optional
URL parameter 'long' I am passing it to my userRepository.getAllUsers
method.
userRepository looks like this:
var db = require('../context').db;
var userRepository = {
getAllUsers: function(callback, long) {
var now = Date.now();
var then = now + 5000;
if (long) {
while (Date.now() < then) {}
}
db.users.find({}, function(err, users) {
callback(users);
});
}
};
module.exports = userRepository;
context.js contains only mongoDB settings (username, password, url).
The idea is the following:
If user enters url: http://website.com/, then 'long' parameter will be
false and userRepository will just get user list from database and will
render to my view.
If user enters url: http://website.com/?long=something, then 'long'
parameter will be true and before extracting user list, getAllUsers will
'sleep' for 5 seconds.
With this approach I am trying to simulate a long-time operation (for
example, if my users colletion has a lot of documents and we are trying to
get them all).
If I am openning: *http://website.com/*, it loads immediately.
If I am oppening: *http://website.com/?long=something*, it loads after ~ 5
seconds as expected.
Now. If I am openning *http://website.com/?long=something* and right after
*that
**http://website.com/ - *they both are loading 5 seconds (second request is
waiting until the first one will end).
That means I am doing something wrong, because requests are handled not
asyncroniously.
What did I do wrong?
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