So I have Problem with Request and NodeJS, is very simple but I am not an Expert.
Code:
logged: function () {
var request = require('request');
test = "nothing!";
request('http://localhost:8080/log', function (error, response, body){
console.log('error:', error);
console.log('statusCode:', response && response.statusCode);
console.log('body:', body);
test = body;
});
console.log('test', test);
Output:
Starting .../
test: nothing!
error: null
statusCode: 200
body: hi
the answer was here: How do I return the response from an asynchronous call?
Request is a asynchronous call!
the Solution is not pretty but it's work!
setTimeout(function() { console.log('test', test);}, 3000);
request is asynchronous so the console.log in the bottom will be executed before test variable is assigned with the body.
So the console.log needs to be inside the request response function.
If you want to use the body later on outside the response function, depends on how you plan to use it.
Related
I use request lib (https://www.npmjs.com/package/request) for a Node application.
And this simple example doesn't work :
console.log(' BEGIN ---- ');
request('http://www.google.com', function (error, response, body) {
console.log('error:', error); // Print the error if one occurred
console.log('statusCode:', response && response.statusCode); // Print the response status code if a response was received
console.log('body:', body); // Print the HTML for the Google homepage.
});
console.log('END ---- ');
I only have BEGIN ---- and END ---- messages in my console, but nothing from the get request.
Did I miss something ?
Nodejs behaves asynchronously, which means when you run your script request takes some time to go and fetch data from the provided link but it will take some time to complete this task therefore other code will not wait for it to complete.
You can use callbacks to wait for the result. Below code is an easy solution for your problem.
const request = require('request')
function req(callback){
console.log(' BEGIN ---- ');
request('http://www.google.com', function (error, response, body) {
console.log('error:', error); // Print the error if one occurred
console.log('statusCode:', response && response.statusCode); // Print the response status code if a response was received
console.log('body:', body); // Print the HTML for the Google homepage.
callback()
});
}
req(function(){
console.log('END ---- ');
})
But for more clean and easy to read code you must learn to use promises or async/await feature in nodejs.
Calling the Riot-Api Im receiving incomplete JSON on a https GET-request.
After debugging, I realized that depending how much I wait (breakpoint) pre-executing the
https on'data' callback Im actually receiving the complete JSON object.
(Average API response time for me is 200-300ms)
let getOptions = function(url) {
return {
host: 'na.api.pvp.net',
port: 443,
path: `${url}?api_key=${apiKey}`,
method: 'GET'
};
}
exports.Call = function(url, callback) {
let response = {};
let req = https.request(getOptions(url), function(res) {
response.statusCode = res.statusCode;
res.on('data', function(data) {
response.json = JSON.parse(data);
callback(response);
});
});
req.on('error', function(err) {
response.err = err;
callback(response);
});
req.end();
};
Running the code without breakpoints or only breaking a short time I run either into error:
JSON.parse(data): Unexpected Token in JSON at position ...
or
JSON.parse(data): Unexptected end of JSON Input.
As I expect the 'data' callback to be executed only after the request is complete im confused about how to fix it (without artificially delaying it ofc.).
http.request returns a stream – its not a simple callback that contains the whole response.
You will have to buffer and concatenate everything if you want to parse the whole response.
I would strongly recomment to use a helper library like got or request
I'm using AWS Lambda to drive an Alexa Skill Kit development. In an attempt to track events, I'd like the script to send an HTTP request on launch, however from the cloud logs it appears as though the http.get function is being skipped during the execution process.
The code is shown below (google.com replaces the analytics tracking url - which has been tested in the browser);
exports.handler = function (event, context) {
var skill = new WiseGuySkill();
var http = require('http');
var url = 'http://www.google.com';
console.log('start request to ' + url)
http.get(url, function(res) {
console.log("Got response: " + res.statusCode);
// context.succeed();
}).on('error', function(e) {
console.log("Got error: " + e.message);
// context.done(null, 'FAILURE');
});
console.log('end request to ' + url);
skill.execute(event, context);
};
The context objects have been commented out to allow for 'skill.execute' to function, yet either way this HTTP request is not executing. Only the 'start' and 'end' console.logs are recorded, those internal in the function do not.
Is this a async issue? Thanks.
You need to make sure the handler is being triggered. There are two ways of accomplishing this:
You could set up a new API endpoint and execute a request on that.
You could hit the Test button and your function would be invoked with the given data.
I copied and pasted your whole snippet except for the first and the last lines (because I don't have customSkill defined anywhere). I was able to get a 200 response code.
In order to successfully complete the http request, the http.get function must be incorporated into a callback function. Else the process will not be completed and will end prematurely, using a callback allows the http request to complete (with or without an error) before continuing with the rest of the function.
WiseGuySkill.prototype.eventHandlers.onLaunch = function (launchRequest, session, response) {
// Call requestFunction to make the http.get call.
// Get response from requestFunction using requestCallback
requestFunction(function requestCallback(err) {
// If error occurs during http.get request - respond with console.log
if (err) {
console.log('HTTP Error: request not sent');
}
ContinueIntent(session,response);
});
};
The function 'requestFunction' calls http.get and fires the callback.
function requestFunction(requestCallback){
var url = "http://www.google.com";
http.get(url, function(res) {
console.log("Got response: " + res.statusCode);
requestCallback(null);
}).on('error', function (e) {
console.log("Got error: ", e);
});
}
And obviously ensure you have required 'http' at the start of the script.
Hope this helps anybody else new to this!
I try to put many callbacks in a callback, but the program will shut down after the return of several success requests and post "socket hang up" error. I try to collect data from response and output them at once, can someone tell me which part goes wrong...
By the way, I hide the details of request method, I promise the request method works on http call.
http.request(options1,function(data){
var condition=data.length;
var result=[];
data.foreach(item,function(data){
http.request(options2, function(data){
if(data) result.push(data);
condition--;
if(condition<=0) console.log(result);
}
});
});
for my http.request method
var request=function(options,callback){
http.request(options,function(res){
var body;
res.on('data',function(chunk){
body+=chunk;
});
res.on('end',function(){
callback(JSON.parse(body));
});
request.end();
};
That's not the correct usage of http.request().
The http.request() callback is passed an IncomingMessage object, not buffered response data.
EDIT: Your custom request() should look something like this, although you should handle errors too. Note the proper placement of request.end() and initializing var body = '':
function request(options, callback) {
http.request(options,function(res) {
var body = '';
res.setEncoding('utf8');
res.on('data',function(chunk) {
body += chunk;
}).on('end',function() {
callback(JSON.parse(body));
});
}).end();
}
You're missing .end() for your requests so that node.js knows you are ready to actually send the HTTP request: http.request(..., ....).end();. This is the cause of your particular error... the server hangs up the connection because it got tired of waiting for your request after the TCP connection was opened.
I probably have some issues with the asyncness of Node.js.
rest.js
var Shred = require("shred");
var shred = new Shred();
module.exports = {
Request: function (ressource,datacont) {
var req = shred.get({
url: 'ip'+ressource,
headers: {
Accept: 'application/json',
},
on: {
// You can use response codes as events
200: function(response) {
// Shred will automatically JSON-decode response bodies that have a
// JSON Content-Type
if (datacont === undefined){
return response.content.data;
//console.log(response.content.data);
}
else return response.content.data[datacont];
},
// Any other response means something's wrong
response: function(response) {
return "Oh no!";
}
}
});
}
}
other.js
var rest = require('./rest.js');
console.log(rest.Request('/system'));
The problem ist if I call the request from the other.js I always get 'undefined'. If I uncomment the console.log in rest.js then the right response of the http request is written to the console. I think the problem is that the value is returned before the actual response of the request is there. Does anyone know how to fix that?
Best,
dom
First off, it is useful to strip down the code you have.
Request: function (ressource, datacont) {
var req = shred.get({
// ...
on: {
// ...
}
});
}
Your Request function never returns anything at all, so when you call it and console.log the result, it will always print undefined. Your request handlers for the various status codes call return, but those returns are inside of the individual handler functions, not inside Request.
You are correct about the asynchronous nature of Node though. It is impossible for you to return the result of the request, because the request will still be in progress when your function returns. Basically when you run Request, you are starting the request, but it can finish at any time in the future. The way this is handled in JavaScript is with callback functions.
Request: function (ressource, datacont, callback) {
var req = shred.get({
// ...
on: {
200: function(response){
callback(null, response);
},
response: function(response){
callback(response, null);
}
}
});
}
// Called like this:
var rest = require('./rest.js');
rest.Request('/system', undefined, function(err, data){
console.log(err, data);
})
You pass a third argument to Request which is a function to call when the request has finished. The standard Node format for callbacks that can fail is function(err, data){ so in this case on success you pass null because there is no error, and you pass the response as the data. If there is any status code, then you can consider it an error or whatever you want.