I have difficulties in something that should be very simple:
Building a simple Express.js server/listener that will receive XML file (lets's say from Postman) and parse it.
Tried different approaches, like XML2J LibXMLjs- nothing works.
Since I am new also to Postman: please advice me also how to post the message from there. (tried Body/Raw/XML - did not work for me).
You can parse xml with xml2js like so:
var parseString = require('xml2js').parseString;
var xml = "<root>Hello xml2js!</root>";
parseString(xml, function (err, result) {
console.dir(result);
});
Related
I need to get number of items of specific directory in Node.js
If I get the items like
var dirItems = fs.readdirSync(__dirname+'/my_dir');
and then get specific item like
dirItems[1]
everything is ok
But if I try to get their number like
dirItems.length
or
Object.keys(dirItems).length
the page doesn't work in the browser
How to get the number of directory items?
UPDATED
My full code:
var http = require('http'),
fs = require('fs');
http.createServer(function(req, res) {
var dirItems = fs.readdirSync(__dirname+'/my_dir');
res.writeHead(200, {'Content-Type': 'text/html'});
res.end(dirItems.length);
}).listen(80, 'localhost');
I was able to reproduce the error nyou get.
res.end() for the basic http server class is very picky about what you send it. You must give it a string (the error you got should have been a big clue here).
So, change this:
res.end(dirItems.length);
to this:
res.end(dirItems.length.toString());
And, it works for me. I was able to reproduce your original error and then make it work by making this simple change.
Logically, you can only send string data as an http response so apparently res.end() isn't smart enough to attempt a string conversion on its own. You have to do it yourself.
FYI, if you use a higher level framework like Express, it is more tolerant of what you send it (it will attempt a string conversion in a situation like this).
Here is how I would do it:
const fs = require('fs');
const dir = './somedir';
fs.readdir(dir, (err, files) => {
console.log(files.length);
});
I've distilled my issue to some really basic functionality here. Basically, we're sending a request to a server (you can go ahead and c/p the URL and see the json document we get in response).
We get the response, we pipe it into a write stream and save it as a .json file - but the problem is that the file keeps being cut off. Is the .json file too large? Or am I missing something? Node.js newbie - massively appreciate any help I can get.
var fs = require('fs');
var url = 'https://crest-tq.eveonline.com/market/10000002/history/?type=https://crest-tq.eveonline.com/inventory/types/34/'
var request = require('request');
request(url).pipe(fs.createWriteStream('34_sell.json'));
var fs = require('fs');
var request = require('request');
var url = 'https://crest-tq.eveonline.com/market/10000002/history/?type=https://crest-tq.eveonline.com/inventory/types/34/';
request(url).pipe(fs.createWriteStream('34_sell.json'));
Not an answer but this is the code I used. I'm using request version 2.74.0. And node version v5.4.1.
Try writing a get request to the url and send the json as response and write an error handling statement like if err then throw err..console log and see the result..hope it works
I have this express application with mongoDB as the database and handlebars as my server-side templating engine. I am not using AngularJS or Ajax in my application.
In one of the routes, I have to render the page as well as send over a json file from the database. However, I am not able to achieve this.
Here is code snippet the my route:
router.get('/disks', function(req, res, next) {
places.find({"category": "disks"}, function(err, disks){
if(err){
throw err;
}
res.render('disks',
{
'risime': JSON.stringify(disks)
});
console.log(disks); // PROPERLY LOGS TO THE CONSOLE
});
});
In the hbs, I am trying to capture it, but I don't even think that it is JSON.
Here is how it gets logged in the client side:
[{"_id":"5704630a7d4cd367f8dsdce7","name":"Seagate",:"This awesome Hard disk",","categories":["SDD","256GB"]}]
What is the issue and how do I resolve it?
It's handlebars that "html escapes" your string (which is what you normally want).
if you don't want that, you can use the "triple-stash" notation, like this:
{{{risime}}}
You can read about this here: http://handlebarsjs.com/#html-escaping
I think you need to add this before render:
res.type('application/json');
The client will know this is a JSON, not a HTML or a plain text and it will be shown correctly.
I hope my answer will help you.
I've got some data from a JSON file, which I use in my HTML getting it first from AngularJS like this:
$http.get('js/data.json').success(function(data) {
$scope.data = data;
});
And I want to update this JSON file after clicking a button in the HTML:
<button ng-click="postData(id)">Post</button>
You cannot write on files via JavaScript only (AngularJS).
You are to go via server side and point your "post" request to a server side script (i.e: PHP) and make that script do the job.
This sort of thing won't work. The file you are trying to write to would be on a server; and as it is right now, it would be a static resource. I'd suggest reading up on Angular resources, here. You can set up your server-side code to perform CRUD operations on the json file, but an actually database would be best. If you prefer to use a json format, Mongodb is your best choice; here is a link to Mongodb University, which offers free courses. I've done it in the past, and it's been great.
Now, for some actually help in your situation:
You can perform a GET request on your json file because it's seen as a static resource. The POST request, however, needs server-side scripting to do anything.
$http.get('api/YOUR_RESOURCE').success(function(data) {
$scope.database = data;
});
$http.post('api/YOUR_RESOURCE', {
data_key: data_value,
data_key2: data_value2
}).success(function(data) {
data[id].available = false;
});
This may be further ahead on your path to learning Angular, but here is a snippet of Node.js server code, with a Mongo database and Mongoose to handle the 'Schema', to help you get an idea of how this works:
var mongoose = require('mongoose'),
YOUR_RESOURCE = mongoose.model('YOUR_RESOURCE');
app.route('/api/YOUR_RESOURCE')
// This should be your GET request; 'api/
.get(
// Get all docs in resource
YOUR_RESOURCE.find().exec(function (err, data) {
if (err) {
return res.status(400).send({
message: SOME_ERROR_HANDLER
});
} else {
res.json(data); // return list of all docs found
}
});)
// Add new doc to database
.post(function (req, res) {
// The keys of the object sent from your Angular app should match
// those of the model
var your_resource = new YOUR_RESOURCE(req.body);
your_resource.save(function (err) {
if (err) {
return res.status(400).send({
message: SOME_ERROR_HANDLER
});
} else {
// returns newly created doc to Angular after successful save
res.json(your_resource);
}
});
);
Here is an SO page with a list of resources on getting started with Node; I recommend Node because of it's ease of use and the fact that it is written in JS. The Mongo University lessons also go through setting up you server for use with the database; you can choose between several flavors, such as Java, .NET, Python or Node.
There is a bit left out in the examples above, such as the Mongoose model and Node setup, but those will be covered in the resources I've linked to on the page, if you choose to read them. Hope this helps :)
So I'm trying to make a very basic node.js server that with take in a request for a string, randomly select one from an array and return the selected string. Unfortunately I'm running into a few problems.
Here's the front end:
function newGame()
{
guessCnt=0;
guess="";
server();
displayHash();
displayGuessStr();
displayGuessCnt();
}
function server()
{
xmlhttp = new XMLHttpRequest();
xmlhttp.open("GET","server.js", true);
xmlhttp.send();
string=xmlhttp.responseText;
}
This should send the request to server.js:
var http = require('http');
var choices=["hello world", "goodbye world"];
console.log("server initialized");
http.createServer(function(request, response)
{
console.log("request recieved");
var string = choices[Math.floor(Math.random()*choices.length)];
console.log("string '" + string + "' chosen");
response.on(string);
console.log("string sent");
}).listen(8001);
So clearly there are several things going wrong here:
I get the feeling the way I am "connecting" these two files isn't correct both in the xmlhttp.open method and in using response.on to send the string back to the front end.
I'm a little confused with how I call this page on localhost. The front end is named index.html and the sever posts to 8001. What address should I be go to on localhost in order to access the initial html page after I have initialized server.js? Should I change it to .listen(index.html) or something like that?
are there other obvious problems with how I am implementing this (using .responsetext etc.)
(sorry for the long multi-question post but the various tutorials and the node.js source all assume that the user already has an understanding of these things.)
Your request should be to the server, NOT the server.js file which instantiates it. So, the request should look something like this: xmlhttp.open("GET","http://localhost:8001/", true); Also, you are trying to serve the front-end (index.html) AND serve AJAX requests at the same URI. To accomplish this, you are going to have to introduce logic to your server.js that will differentiate between your AJAX requests and a normal http access request. To do this, you'll want to either introduce GET/POST data (i.e. call http://localhost:8001/?getstring=true) or use a different path for your AJAX requests (i.e. call http://localhost:8001/getstring). On the server end then, you'll need to examine the request object to determine what to write on the response. For the latter option, you need to use the 'url' module to parse the request.
You are correctly calling listen() but incorrectly writing the response. First of all, if you wish to serve index.html when navigating to http://localhost:8001/, you need to write the contents of the file to the response using response.write() or response.end(). First, you need to include fs=require('fs') to get access to the filesystem. Then, you need to actually serve the file.
XMLHttpRequest needs a callback function specified if you use it asynchronously (third parameter = true, as you have done) AND want to do something with the response. The way you have it now, string will be undefined (or perhaps null), because that line will execute before the AJAX request is complete (i.e. the responseText is still empty). If you use it synchronously (third parameter = false), you can write inline code as you have done. This is not recommended as it locks the browser during the request. Asynchronous operation is usually used with the onreadystatechange function, which can handle the response once it is complete. You need to learn the basics of XMLHttpRequest. Start here.
Here is a simple implementation that incorporates all of the above:
server.js:
var http = require('http'),
fs = require('fs'),
url = require('url'),
choices = ["hello world", "goodbye world"];
http.createServer(function(request, response){
var path = url.parse(request.url).pathname;
if(path=="/getstring"){
console.log("request recieved");
var string = choices[Math.floor(Math.random()*choices.length)];
console.log("string '" + string + "' chosen");
response.writeHead(200, {"Content-Type": "text/plain"});
response.end(string);
console.log("string sent");
}else{
fs.readFile('./index.html', function(err, file) {
if(err) {
// write an error response or nothing here
return;
}
response.writeHead(200, { 'Content-Type': 'text/html' });
response.end(file, "utf-8");
});
}
}).listen(8001);
console.log("server initialized");
frontend (part of index.html):
function newGame()
{
guessCnt=0;
guess="";
server();
displayHash();
displayGuessStr();
displayGuessCnt();
}
function server()
{
xmlhttp = new XMLHttpRequest();
xmlhttp.open("GET","http://localhost:8001/getstring", true);
xmlhttp.onreadystatechange=function(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
string=xmlhttp.responseText;
}
}
xmlhttp.send();
}
You will need to be comfortable with AJAX. Use the mozilla learning center to learn about XMLHttpRequest. After you can use the basic XHR object, you will most likely want to use a good AJAX library instead of manually writing cross-browser AJAX requests (for example, in IE you'll need to use an ActiveXObject instead of XHR). The AJAX in jQuery is excellent, but if you don't need everything else jQuery offers, find a good AJAX library here: http://microjs.com/. You will also need to get comfy with the node.js docs, found here. Search http://google.com for some good node.js server and static file server tutorials. http://nodetuts.com is a good place to start.
UPDATE: I have changed response.sendHeader() to the new response.writeHead() in the code above !!!
Express makes this kind of stuff really intuitive. The syntax looks like below :
var app = require('express').createServer();
app.get("/string", function(req, res) {
var strings = ["rad", "bla", "ska"]
var n = Math.floor(Math.random() * strings.length)
res.send(strings[n])
})
app.listen(8001)
https://expressjs.com
If you're using jQuery on the client side you can do something like this:
$.get("/string", function(string) {
alert(string)
})
I was facing following error with code (nodejs 0.10.13), provided by ampersand:
origin is not allowed by access-control-allow-origin
Issue was resolved changing
response.writeHead(200, {"Content-Type": "text/plain"});
to
response.writeHead(200, {
'Content-Type': 'text/html',
'Access-Control-Allow-Origin' : '*'});
Here is a fully functional example of what you are trying to accomplish. I created the example inside of hyperdev rather than jsFiddle so that you could see the server-side and client-side code.
View Code:
https://hyperdev.com/#!/project/destiny-authorization
View Working Application: https://destiny-authorization.hyperdev.space/
This code creates a handler for a get request that returns a random string:
app.get("/string", function(req, res) {
var strings = ["string1", "string2", "string3"]
var n = Math.floor(Math.random() * strings.length)
res.send(strings[n])
});
This jQuery code then makes the ajax request and receives the random string from the server.
$.get("/string", function(string) {
$('#txtString').val(string);
});
Note that this example is based on code from Jamund Ferguson's answer so if you find this useful be sure to upvote him as well. I just thought this example would help you to see how everything fits together.