I have the following backend http endpoint implemented with NodeJS and expressJS
app.get("/api/stocks/lookup/:qry", function(req, res) {
getJson(lookupSearch(req.params.qry), function(json) {
var quotes = [];
und.forEach(json, function(d) {
getJson(quoteSearch(d.Symbol), function(j) {
quotes.push(j);
if (json.length == quotes.length) {
res.send(quotes);
}
});
});
});
});
var getJson = function(search, cb) {
http.request(search, function(response) {
var raw = '';
response.on('data', function(d) {
raw += d;
});
response.on('end', function() {
cb(JSON.parse(raw));
});
response.on('error', function(err) {
console.error(err);
});
}).end();
};
What I do not understand is why this only works sometimes and why other times I get this error message from curl: curl: (52) Empty reply from server My solution that checks the lengths of json and quotes seems correct to me and so I think I must have misused some library. However, as I am new to asynchronous code (the http request in getJson) I am not 100% sure this is correct.
I asked a question with similar code here: syntax and methods for placing callbacks in nodejs Note that the 'homebrewed' solution with incrementing and decrementing a count only works sometimes as well. I do not want to use JQuery inside node either.
Why does the above http request only work sometimes?
Related
Am trying to design a REST api which will throw an aggregated response from multiple apis.
Following is the NodeJS code am trying to execute -
Pseudo Code start
//endpoint to be called from a browser / REST client
router.get('/api/v1/getItems', (req, response, next) => {
var result = {} // hold the aggregated response from multiple apis
//internally fire another endpoint & add the response over to the var result
http.get(endpoint 1, function(resp){
add response to result})
http.get(endpoint 2, function(resp){
add response to result
})
return response.json(result);
}
Pseudo Code end
// endpoint to be called from the browser or REST Client.
router.get('/api/v1/getItems', (req, response, next) => {
var results = {};
// Nested Endpoint 1
var optionsgetmsg = {
host : 'host.domain.com', // tthe domain name
port : 9043,
path : '/services/itemdata', // the rest of the url
method : 'GET' // do GET
};
//child endpoint
var reqGet = http.request(optionsgetmsg, function(res) {
res.on('data', function(d) {
console.log("d "+ d); // child response
results.itemdata = d;
return response.send(results);
//process.stdout.write(d);
});
res.on('end', function(d){
})
});
reqGet.end();
reqGet.on('error', function(e) {
console.error(e);
});
});
The result in the above case should be the output 'd'. The output 'd' is the response from the child endpoint.
Actual result am getting is an empty object. {}
If you are sending JSON, you must set the headers correctly and the response:
//child endpoint
var reqGet = http.request(optionsgetmsg, function(res) {
res.on('data', function(d) {
res.setHeader('Content-Type', 'application/json');
var results = d;
response.send(JSON.stringify(results));
});
It is unclear as to what exactly you are asking for.
I'm trying to request some information from an HTTPS API using Restify. The following works fine:
curl 'https://api.mercadolibre.com/sites/MLA/search?q=cartera&seller_id=156853713&limit=10&offset=0'
However, this hangs:
var client = restify.createClient({
url: "https://api.mercadolibre.com"
});
search = function(response, name, store_id, limit, offset) {
client.get("/sites/MLA/search?q=cartera&seller_id=156853713&limit=10&offset=0", function (err, req) {
assert.ifError(err); // connection error
var str = ''
req.on('result', function (err, v_res) {
assert.ifError(err); // HTTP status code >= 400
v_res.on('data', function (chunk) {
str += chunk;
});
v_res.on('end', function () {
response.send(str)
});
});
});
}
with the following error: ECONNRESET.
Googling around I found this post: Node.js Https request Error but the answer does not seem to work for me.
Any ideas?
Thanks
I successfully wrote app in node.js working with http.get. Problem is, that if page doesn't exist, it make an error that terminates the app. Is any way how to declare timeout. After timeout it should stop waiting for response and let app continue (if written synchronously)
Thanks for all advices...
I'm responding thinking that you are trying to retrieve info via http.get.
You can see the validate using the response status code.
http.get(url, function(res) {
if (res.statusCode !== 200) {
Your custom handler
} else {
var body = '';
res.on('data', function(chunk) {
body += chunk;
});
res.on('end', function() {
console.log(body);
});
}
}).on('error', function(e) {
console.log("error: ", e);
});
A fully implemented example can be found her https://gist.github.com/pasupulaphani/9630789
You can set timeout and emit an error/abort if the request takes too long but this has to be done in application logic.
Found a better/sophisticated solution to handle timeouts in other post :
https://stackoverflow.com/a/12815321/2073176
Here is the thing :
I have a client which sends data to a server. This server has to contact an external A.P.I. and send back its response to the client. I just can't figure out how and where I can contact the external A.P.I once the server has got the client data.
I route client data like this :
app.post('/getAutoComplete', routes.read);
routes.read retrieves the data within req.body. With my nodejs version (without express framework), I then request the api this way :
var http = require('http'), options = {
host : "192.168.1.38",
port : 8080,
path : "/myURL",
method : 'POST'
};
var webservice_data = "";
var webservice_request = http.request(options, function(webservice_response)
{
webservice_response.on('error', function(e){ console.log(e.message); });
webservice_response.on('data', function(chunk){ webservice_data += chunk;});
webservice_response.on('end', function(){res.send(webservice_data);});
});
webservice_request.write(req.body);
webservice_request.end();
The problem is that i'd like to use native expressJS method like app.post but I don't know how because :
Express (app) object is not available here (declared in app.js but not in the route file)
I don't know how to send POST data with app.post
Any suggestion ?
app.post('/getAutoComplete', routes.read);
// assuming routes.read lookes something like this
routes.read = function read(req, res) {
var http = require('http'), options = {
host : "192.168.1.38",
port : 8080,
path : "/myURL",
method : 'POST'
};
var webservice_data = "";
var webservice_request = http.request(options, function(webservice_response)
{
webservice_response.on('error', function(e){ console.log(e.message); });
webservice_response.on('data', function(chunk){ webservice_data += chunk;});
webservice_response.on('end', function(){res.send(webservice_data);});
});
webservice_request.write(req.body);
webservice_request.end();
};
Also check out https://github.com/mikeal/request It's the de-facto module for doing web requests in node.
routes.read is a function. You can call it with extra parameters, so for example
app.post('/getAutoComplete', function(req,res) {
var q = req.query.q; // or whatever data you need
routes.read(q, function(err, response) {
if (err) throw err;
return res.json(response);
});
});
Now make the routes.read function use the first parameter as the query and when it's gathered the response from the remote API, call the second parameter with any error as the first parameter and the response as the second one.
Update This answer has already been picked as an answer, but it'd be more helpful if I showed an example of routes.read, too:
routes.read = function(q, cb) {
// pretend we calculate the result
var result = q * 10;
if (result > 100) {
// call the callback with error set
return cb("q value too high");
}
// all is well, use setTimeout to demonstrate
// an asynchronous return
setTimeout(function() { cb(null, result) }, 2000);
};
app.get('/', function(req, res){
var options = {
host: 'www.google.com'
};
http.get(options, function(http_res) {
http_res.on('data', function (chunk) {
res.send('BODY: ' + chunk);
});
res.end("");
});
});
I am trying to download google.com homepage, and reprint it, but I get an "Can't use mutable header APIs after sent." error
Anyone know why? or how to make http call?
Check out the example here on the node.js doc.
The method http.get is a convenience method, it handles a lot of basic stuff for a GET request, which usually has no body to it. Below is a sample of how to make a simple HTTP GET request.
var http = require("http");
var options = {
host: 'www.google.com'
};
http.get(options, function (http_res) {
// initialize the container for our data
var data = "";
// this event fires many times, each time collecting another piece of the response
http_res.on("data", function (chunk) {
// append this chunk to our growing `data` var
data += chunk;
});
// this event fires *one* time, after all the `data` events/chunks have been gathered
http_res.on("end", function () {
// you can use res.send instead of console.log to output via express
console.log(data);
});
});