I've been playing with nodejs for a few months now but from last night it stated acting funny.
It's such a stupid problem that is better explained with an example.
This is my code:
FILE-A:
var Q = require('q');
var user = require('../p/user');
module.exports = {
test: function() {
console.log("*****************************************");
console.log(user);
console.log(require('../p/user'));
console.log("*****************************************");
}
};
and FILE-B:
var fileA = require('../fileA');
var Q = require('q');
fileA.test();
Very simple! The problem is that "user" imported into FILE-A is empty! This is the output:
*****************************************
{}
{ get: [Function],
update: [Function],
getProfilePicture: [Function] }
*****************************************
As you can see if I call directly require() in the code, everything is fine!
I feel stupid cause obviously is my fault but I cannot find a solution. do you have any idea of what can be causing this problem?
Thanks a lot!
UPDATE: this is the ../p/user file
/************************************
*
***********************************/
var Q = require('q');
var cassandra = require('../../db/cassandra');
var dateManager = require('../../commons/DateManager');
var db = "test";
var table = "user";
module.exports = {
...
};
Solved....but you are not going to like it, I just reinstalled nodejs and everything is fine now! (same version - v4)
I'm very upset, this is not the way I like to deal with problems and it's seriously shaking my confidence in nodejs. On the other hand, it's such a basic/common scenario that I'm keen on saying it was my fault!
Sorry for the non-solution!
Related
simple Q: How do I access the callback from rimraf? See here.
Can't wrap my head around how to structure the code - I'm trying for example:
var rimraf = require('rimraf');
var removeDir = rimraf(p, callback);
var p = 'docs/mydirectory';
removeDir(p, function(cb){
console.log(cb)
});
But receiving callback undefined.. I'm probably doing something completely wrong! Can someone point me in the right direction? Cheers
var removeDir = rimraf(p, callback);
Is calling the rimraf function, not setting a reference to it. If you want to call it removeDir then use it instead...
var removeDir = require('rimraf');
var p = 'docs/mydirectory';
removeDir(p, function(err){
console.log('dir removed');
});
I have two files, a main and a module file.
//module.js
module.exports.filesystem = "hello!";
//main.js
var filefunctions = require('./module.js');
console.log(filefunctions.filesystem);
//returns "hello!"
This works as expected. I'm not sure why the following, doesn't though:
//module.js
var filefunctions = require('./module.js');
console.log(filefunctions[0]);
//main.js
exports.filesystem = "hello!";
I was under the impression that module.exports would create an array, like
module.exports = {
filesystem: "hello!";
}
Is there something obvious in the syntax that I'm missing? Just trying to wrap my head around these concepts. Any help is appreciated. Thanks!
your assumption of below code is correct,
module.exports = {
filesystem: "hello!";
}
the mistake is, you cannot access object attributes as obj[0], can access them as obj[Object.keys(obj)[0]], try the below code:
console.log(filefunctions[Object.keys(filefunctions)[0]]);
I've run into an issue with the Mongoose Getting Started guide.
I have MongoDB running and everything is working perfectly until I add the last line:
Kitten.find({ name: /^Fluff/ }, callback)
When I node server.js I get this error:
OverwriteModelError: Cannot overwrite Kitten model once compiled.
Here's the full error and my server.js.
Any idea what I'm doing wrong?
P.S. I'm running node 10.26, npm 1.4.13, express 4.4.3 & mongoose 3.8.12 on OS X 10.9.3.
You get the error because callback in Kitten.find({ name: /^Fluff/ }, callback) calls var Kitten = mongoose.model('Kitten', kittySchema); again. Change
Kitten.find({ name: /^Fluff/ }, callback)
to something like:
Kitten.find({ name: /^Fluff/ }, function(err, kittens) {
});
It doesn't make sense to call the callback function again.
I thought this could be useful to someone else who tries it...
I started looking into mongoose and tried Getting Started guide. I don't see the above error happening where it was reported. However, I did see it intermittently. If it happens, follow #3 below. Here are my observations:
Issue#1. If I copy paste the whole code I see an issue with "I don't have a name" as the single quote in don't is not escaped.
Solution#1. I tried to escape with \ and \\ but it didn't work. Google search didn't help. After some research I found that it is forgiving for single quotes outside the function. But, inside the function it won't work. So, I defined a variable outside the function. Probably better to define strings in a separate document for localization anyways. Above all, it works. :)
Issue#2. I see the issue at
fluffy.speak();
TypeError: fluffy.speak is not a function
Here since the first 'mongoose.model(...)' doesn't have this method, adding it later and re-running 'mongoose.model(...)' will not help.
Solution#2. Comment the first 'mongoose.model(...)'
Issue#3. When I copy paste the code from the web site, it is causing weird errors.
Solution#3. Just deleted all the tabs and empty spaces at the end of lines in a Notepad++. That took care of it.
Here is the code that worked for me (Needless to say, if it doesn't work, please copy paste first in notepad):
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test');
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection.error:'));
db.once('open', function(callback) {
//yay!
});
var kittySchema = mongoose.Schema({
name: String
});
//var Kitten = mongoose.model('Kitten', kittySchema);
//var silence = new Kitten({ name: 'Silence' });
//console.log(silence.name);
//console.log(silence);
var noname = "I don't have a name";
kittySchema.methods.speak = function () {
var greeting = this.name
? "Meow name is " + this.name
: noname;
console.log(greeting);
}
var Kitten = mongoose.model('Kitten', kittySchema);
var fluffy = new Kitten({ name : 'fluffy' });
fluffy.speak();
I'm really confused about a variable scope issue with a file required via a path in a config file. Why does my Mongoose schema method "see" the required objects when called from within the model file but not when called from my app.js file? I'm convinced that I must be doing something obviously wrong but I can't see it.
The Node project has the following (simplified) structure:
|models
-index.js
-story.js
-post.js
-app.js
-config.js
This is config.js:
config = {};
config.test = 'test';
config.models = __dirname + '/models';
module.exports = config;
This is story.js:
var config = require('../config.js');
var models = require(config.models);
var foo = {};
foo.bar = 'baz';
var storySchema = mongoose.Schema
({
author: {type: mongoose.Schema.Types.ObjectId},
root: {type: mongoose.Schema.Types.ObjectId, default: null}
});
storySchema.methods.test = function()
{
console.log(foo.bar);
console.log(config.test);
console.log(models);
}
var Story = exports.model = mongoose.model('story', storySchema);
When I create a new Story in app.js and call its test() method, I get this output:
baz (so I know it's seeing objects in the same file)
test (so I know it's seeing variables in the config file)
{} (this "should" log my models object but it logs an empty object, why?)
When I create a new Story object within the story.js file, and run it (node ./models.story.js) the values returned are as expected (the models object is logged rather than an empty object).
Update, here are the index.js and app.js files:
index.js:
module.exports = {
post: require('./post'),
story: require('./story')
};
app.js:
var config = require('./config');
var models = require(config.models);
var story = new models.story.model();
story.test();
I believe the issue is that you've created a circular dependency. Story executes require(config.models) which requires Story again inside index.js.
Rather than storing a string and requireing it everywhere, try storing the models directly in config.models:
config.js
module.exports = {
test: 'test',
models: require(__dirname + '/models')
};
In case anyone runs into this same issue, I wanted to point to a couple resources I came across that helped me resolve the issue. As ssafejava pointed out, the problem does have to do with circular dependency (although ssafejava's solution did not entirely resolve the issue) . What worked for me was designing this dependency out of my application but there are other options if doing so is not possible. See the following issues' comments for a better explanation (in particular, see 'isaacs' comments):
https://github.com/joyent/node/issues/1490
https://github.com/joyent/node/issues/1418
I'm a beginner in Node.js, and was having trouble with this piece of code.
var fs = require('fs');
Framework.Router = function() {
this.run = function(req, res) {
fs.exists(global.info.controller_file, function(exists) {
if (exists) {
// Here's the problem
res.writeHead(200, {'Content-Type':'text/html'});
var cname = App.ucfirst(global.info.controller)+'Controller';
var c = require(global.info.controller_file);
var c = new App[cname]();
var action = global.info.action;
c[action].apply(global.info.action, global.info.params);
res.end();
} else {
App.notFound();
return false;
}
});
}
};
The problem lies in the part after checking if the 'global.info.controller_file' exists, I can't seem to get the code to work properly inside the: if (exists) { ... NOT WORKING }
I tried logging out the values for all the variables in that section, and they have their expected values, however the line: c[action].apply(global.info.action, global.info.params);
is not running as expected. It is supposed to call a function in the controller_file and is supposed to do a simple res.write('hello world');. I wasn't having this problem before I started checking for the file using fs.exists. Everything inside the if statement, worked perfectly fine before this check.
Why is the code not running as expected? Why does the request just time out?
Does it have something to do with the whole synchronous vs asynchronous thing? (Sorry, I'm a complete beginner)
Thank you
Like others have commented, I would suggest you rewrite your code to bring it more in-line with the Node.js design patterns, then see if your problem still exists. In the meantime, here's something which may help:
The advice about not using require dynamically at "run time" should be heeded, and calling fs.exists() on every request is tremendously wasteful. However, say you want to load all *.js files in a directory (perhaps a "controllers" directory). This is best accomplished using an index.js file.
For example, save the following as app/controllers/index.js
var fs = require('fs');
var files = fs.readdirSync(__dirname);
var dotJs = /\.js$/;
for (var i in files) {
if (files[i] !== 'index.js' && dotJs.test(files[i]))
exports[files[i].replace(dotJs, '')] = require('./' + files[i]);
}
Then, at the start of app/router.js, add:
var controllers = require('./controllers');
Now you can access the app/controllers/test.js module by using controllers.test. So, instead of:
fs.exists(controllerFile, function (exists) {
if (exists) {
...
}
});
simply:
if (controllers[controllerName]) {
...
}
This way you can retain the dynamic functionality you desire without unnecessary disk IO.