I am trying to add some additional values to each item of an array. So I have an array with objects and they have: x, y and z fields. I then want to add additional items to each object in the array based on a http.get call's response.
Main array is: posts
See code below:
router.get('/api/posts', function(req, res){
postModel.find({})
.limit(10)
.exec(function(err, posts) {
var options = {
host: 'localhost',
port: 3000,
path: '/user?id=12345678',
method: 'GET'
};
if(posts){
posts.forEach(function(post) {
var req = http.get(options, function(res) {
var bodyChunks = [];
res.on('data', function(chunk) {
bodyChunks.push(chunk);
}).on('end', function() {
var body = Buffer.concat(bodyChunks);
var parsedBody = JSON.parse(body);
post.fullname = parsedBody.user.fullname;
post.profilePic = parsedBody.user.profilePic;
});
});
});
res.json({
posts : posts
});
} else {
res.send('Post does not exist');
}
});
});
At the time of the post.profilePic = parsedBody.user.profilePic - the profilePic variable is there but when I get a response from node via res.json, the additional values are not.
What am I missing here? I use this approach with my Angular frontend all the time without an issue.
Thanks
This is an incredibly common problem, you are treating asynchronous code as if it were synchronous. http.get does not complete immediately, nor does it block the code from continuing on, therefore res.json is called before your requests complete. There are a ton of ways to fix this, I'll post my favorite - Javascript Promises.
// use map instead of forEach to transform your array
// of posts into an array of promises
var postPromises = posts.map(function(post) {
return new Promise(function(resolve) {
var req = http.get(options, function(res) {
var bodyChunks = [];
res.on('data', function(chunk) {
bodyChunks.push(chunk);
}).on('end', function() {
var body = Buffer.concat(bodyChunks);
var parsedBody = JSON.parse(body);
post.fullname = parsedBody.user.fullname;
post.profilePic = parsedBody.user.profilePic;
// resolve the promise with the updated post
resolve(post);
});
});
});
});
// once all requests complete, send the data
Promise.all(postPromises).then(function(posts) {
res.json({
posts: posts
});
});
Node work according to callbacks. You callbacks not completed in the forEach Loop and you are giving response to user. This is the issue.
Write code for that I can suggest solution.
router.get('/api/posts', function(req, res){
postModel.find({})
.limit(10)
.exec(function(err, posts) {
var options = {
host: 'localhost',
port: 3000,
path: '/user?id=12345678',
method: 'GET'
};
if(posts){
var EventEmitter = require('events');
var HttpEvent = new EventEmitter();
let counts = 0;
let length = posts.length;
posts.forEach(function(post) {
var req = http.get(options, function(res) {
var bodyChunks = [];
res.on('data', function(chunk) {
bodyChunks.push(chunk);
}).on('end', function() {
var body = Buffer.concat(bodyChunks);
var parsedBody = JSON.parse(body);
posts.fullname = parsedBody.user.fullname;
posts.profilePic = parsedBody.user.profilePic;
HttpEvent.emit('done');
});
});
});
HttpEvent.on('done',()=>{
counts += 1;
if(counts == length){
res.json({
posts : posts
});
}
})
} else {
res.send('Post does not exist');
}
});
});
One more wrong thing you are doing is
post.fullname = parsedBody.user.fullname;
post.profilePic = parsedBody.user.profilePic;
It should be
posts.fullname = parsedBody.user.fullname;
posts.profilePic = parsedBody.user.profilePic;
Related
I would like to use two IBM Watson services and combine the responses from both in one variable and return it as a callback. I couldn't figure out how to get response1 value outside the http request to combine it with response2 from the other IBM Watson service.
I tried the below code and it didn't work. I read that I can use promises, but I'm pretty new to this, and couldn't figure out how to do this.
Can anyone help please?
const AWS = require('aws-sdk');
var http = require('https');
exports.handler = (event, context, callback) => {
var text = JSON.stringify(event.text);
var options = {
method: process.env.method,
hostname: process.env.watson_hostname,
port: null,
path: process.env.path,
headers: {
'content-type': process.env.content_type,
authorization: process.env.authorization,
'cache-control': process.env.cache_control,
'X-Watson-Learning-Opt-Out': 'true'
}
};
var req = http.request(options, function (res) {
var chunks = "";
res.on("data", function (chunk) {
chunks+ = chunk.toString();;
});
res.on("end", function () {
var response1 = (chunks);
//////////////here I need to get reponse2
var response2 = IBM2();
var bothResponses = response1 + response2
callback(null,bothResponses)
});
})
req.write(text);
req.end()
function IBM2(){
var text = JSON.stringify(event.text);
var options = {
method: process.env.method2,
hostname: process.env.watson_hostname2,
port: null,
path: process.env.path2,
headers: {
'content-type': process.env.content_type2,
authorization: process.env.authorization2,
'cache-control': process.env.cache_control,
'X-Watson-Learning-Opt-Out': 'true'
}
};
var req = http.request(options, function (res) {
var chunks = [];
res.on("data", function (chunk) {
chunks.push(chunk);
});
res.on("end", function () {
var response2 = JSON.parse(Buffer.concat(chunks));
return(response2)
}
Return a promise from your IBM2 function and handle using async await in the calling function. Notice the async keyword before on end callback.
I have tried to add Promise to your existing flow:
const AWS = require('aws-sdk');
var http = require('https');
exports.handler = (event, context, callback) => {
var text = JSON.stringify(event.text);
var options = {
method: process.env.method,
hostname: process.env.watson_hostname,
port: null,
path: process.env.path,
headers: {
'content-type': process.env.content_type,
authorization: process.env.authorization,
'cache-control': process.env.cache_control,
'X-Watson-Learning-Opt-Out': 'true'
}
};
var req = http.request(options, function (res) {
var chunks = "";
res.on("data", function (chunk) {
chunks += chunk.toString();;
});
res.on("end", async function () {
var response1 = (chunks);
//////////////here I need to get reponse2
var response2 = await IBM2();
// validate response2 (in case IBM2 throws error)
var bothResponses = response1 + response2;
callback(null,bothResponses)
});
});
req.write(text);
req.end();
function IBM2(){
return new Promise((resolve, reject) =>{
var text = JSON.stringify(event.text);
var options = {
method: process.env.method2,
hostname: process.env.watson_hostname2,
port: null,
path: process.env.path2,
headers: {
'content-type': process.env.content_type2,
authorization: process.env.authorization2,
'cache-control': process.env.cache_control,
'X-Watson-Learning-Opt-Out': 'true'
}
};
var req = http.request(options, function (res) {
var chunks = [];
res.on("data", function (chunk) {
chunks.push(chunk);
});
res.on("end", function () {
var response2 = JSON.parse(Buffer.concat(chunks));
resolve(response2)
});
res.on("error", function (err) {
reject(err);
});
})
});
}
};
Before making any changes to your code, I would suggest you go thru these topics first.
For reference, do take a look into the concept of promises and async-await
Promiese
Async/Await
Dont know if you have other errors, but it looks like youre not waiting for response2 to finish, maybe something like
const response2 = await IBM2():
or if you want to use promises maybe something like:
res.on('end', function () {
var response2 = IBM2().then(
val => {
var bothResponses = response1 + val;
callback(null, bothResponses);
},
reject => {
/* handle rejection here */
},
);
});
I have the following code.
I'm trying to make an API call (retrieve) passing since (obj.since), therefore, every time I make the call the API does not retrieve all data. However, so far, I haven't found the way to get since from the last record on my database.
var express = require("express");
var article = require("../models/article");
var request = require('request');
article.findOne({}, {since:1, _id:0}, { sort: { 'since' : -1 } }, function (err,obj) {
var **dataString** = `'{"consumer_key":"XXXXX", "access_token":"XXXXXXX", "since":"${obj.since}"}'`;
});
var options = {
url: 'https://xxxxxxxxx.com/v3/get',
method: 'POST',
headers: headers,
body: **dataString**
}
function callback(error, response, body) {
if (!error && response.statusCode == 200) {
let package = JSON.parse(body);
for(var attributename in package.list){
var title = package.list[attributename]["given_title"] ;
var url = package.list[attributename]["given_url"] ;
var newArticle = {title: title, url: url, since: since}
article.create(newArticle, function(error, newlyCreated){
if(error){
console.log(error);
} else {
console.log(newlyCreated);
}
});
}
}
else {
console.log(error);
}
};;
request(options,callback)
How can I make an API call getting the obj.since from the database (MongoDB) and pass it to an object (options)?
You are doing async callback style operation in for loop which is causing this issue. I will change few things
Change findOne to have exec at the end so it returns promise
article.create already returns a promise if no callback specified.
Convert request to a promise style.
Use for..of loop to do async operation.
The code will look like this
var express = require("express");
var article = require("../models/article");
var request = require('request');
function hitApi(dataString) {
return new Promise((resolve, reject) => {
var options = {
url: 'https://xxxxxxxxx.com/v3/get',
method: 'POST',
headers: headers,
body: dataString
}
request(options, error, response, body => {
if (err) {
reject(err);
}
resolve(body);
});
});
}
async function perform() {
const dataString = await article.findOne({}, {since:1, _id:0}, { sort: { 'since' : -1 } }).exec();
const response = await hitApi(dataString);
const package = JSON.parse(response.body);
for (const attributename of package.list) {
var title = package.list[attributename]["given_title"] ;
var url = package.list[attributename]["given_url"] ;
var newArticle = {title: title, url: url, since: since}
const newlyCreated = await article.create(newArticle);
console.log(newlyCreated);
}
}
You can then call perform function. There might be few syntax error but you will get an idea.
I am calling a javascript function , which in turn calls a web service;The response of this service is used to call another function which also calls a service. At end of both services we set session attributes. This code gives no errors, but the callback gets called before the service has returned data. The main motive of this code is to set the session attributes before return of flow from this code, when the callback gets called before the service has returned values the session attributes are not set and the requirement of the code is not fulfilled.
'use strict';
function close(sessionAttributes, fulfillmentState, message) {
return {
sessionAttributes,
dialogAction: {
type: 'Close',
fulfillmentState,
message : 'For security purpose answer these questions '
},
};
}
function getSecurityQuestions(intentRequest, context, post_options, callback){
const sessionAttributes = intentRequest.sessionAttributes || {};
var policynumber = sessionAttributes.policynumber;
var interactionID = sessionAttributes.interactionID;
var body = "";
var body2;
const http = require('https');
const promise = new Promise((resolve, reject) => {
const post_data = JSON.stringify({"Purpose":"SecurityQuestions", "InteractionID":interactionID, "SearchStringAcctNum":policynumber});
//ignores SSL
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
var post_request = http.request(post_options, function(res) {
res.on('data', function(chunk) {
body += chunk;
});
res.on('end', function() {
context.done(body);
resolve(body);
});
res.on('error', function(e) {
reject(Error(e.message));
context.fail('error:' + e.message);
});
});
// post the data
post_request.write(post_data);
post_request.end();
});
callback( promise.then((body) => {
body2 = JSON.parse(body);
sessionAttributes.question1 = body2.SecurityDetails[0].Question;
close(sessionAttributes, 'Fulfilled');
}, (error) => {
console.log(error.message);
})
);
}
function getInteraction(intentRequest, context, callback) {
const slots = intentRequest.currentIntent.slots;
var policynumber = "PA"+slots.PolicyNumber;
var questionOne = slots.questionOne;
var questionTwo = slots.questionTwo;
const sessionAttributes = intentRequest.sessionAttributes || {};
console.log("policy number : "+policynumber + "question 1 : "+questionOne + "question 2 : "+questionTwo);
sessionAttributes.policynumber = policynumber;
var body = "";
var body2;
// An object of options to indicate where to post to
var post_options = {
host: 'example.com',
protocol: 'https:',
port: '3000',
path: '/hiddenPath',
method: 'POST',
headers: {
'Content-Type': 'application/json'
}
};
const http = require('https');
const promise = new Promise((resolve, reject) => {
const post_data = JSON.stringify({"Purpose":"CreateInteraction"});
//ignores SSL
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
var post_request = http.request(post_options, function(res) {
res.on('data', function(chunk) {
body += chunk;
});
res.on('end', function() {
context.done(body);
resolve(body);
});
res.on('error', function(e) {
console.log("rejected here");
reject(Error(e.message));
context.fail('error:' + e.message);
});
});
// post the data
post_request.write(post_data);
post_request.end();
});
callback( promise.then((body) => {
body2 = JSON.parse(body);
console.log("interaction ID : "+body2.InteractionID);
sessionAttributes.interactionID = body2.InteractionID;
getSecurityQuestions(intentRequest, context, post_options, callback);
}, (error) => {
console.log('Promise rejected.');
console.log(error.message);
}));
}
// --------------- Intents -----------------------
/**
* Called when the user specifies an intent for this skill.
*/
function dispatch(intentRequest, context, callback) {
const intentName = intentRequest.currentIntent.name;
if (intentName === 'currIntent') {
return getInteraction(intentRequest, context, callback);
}
throw new Error(`Intent with name ${intentName} not supported`);
}
// --------------- Main handler -----------------------
function loggingCallback(response, originalCallback) {
console.log("logging callback called......");
originalCallback(null, response);
}
exports.handler = (event, context, callback) => {
try {
dispatch(event, context, (response) => loggingCallback(response, callback));
} catch (err) {
callback(err);
}
};
You should resolve your promise only after the request ends.. Have updated your sample below. Hope it helps. Also, you were sending an invalid object as your post body. Fixed that as well.
function getValue(context, post_options, callback) {
var body = "";
var body2;
const http = require('http');
const promise = new Promise((resolve, reject) => {
// INVALID OBJECT
//const post_data = JSON.stringify({"something"});
const post_data = JSON.stringify({
something: "something"
});
//ignores SSL
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
var post_request = http.request(post_options, function(res) {
res.on('data', function(chunk) {
body += chunk;
console.log("inside " + JSON.stringify(body));
// DONT RESOLVE HERE, REQUEST IS NOT COMPLETE
//resolve(body);
});
res.on('end', function() {
context.done(body);
//RESOLVE HERE INSTEAD
resolve(body);
});
res.on('error', function(e) {
reject(Error(e.message));
context.fail('error:' + e.message);
});
});
// post the data
post_request.write(post_data);
post_request.end();
});
promise.then((body) => {
console.log("response data " + JSON.stringify(body));
body2 = JSON.parse(body);
callback(delegate(sessionAttributes, intentRequest.currentIntent.slots));
}, (error) => {
console.log('Promise rejected.');
console.log(error.message);
});
}
First Node/Express app.
I'm having a hard time wrapping my head around on how to retrieve data from an endpoint and rendering it in the browser.
I have a dataservice.js that gets a JSON object from an endpoint like this:
const http = require('http');
getFinhockeyData = function() {
http.get('http://tilastopalvelu.fi/ih/modules/mod_standings/helper/standings.php?statgroupid=3545', (res) => {
console.log(`Got response: ${res.statusCode}`);
var body = "";
res.on('data', function (chunk) {
body += chunk;
})
res.on('end', function () {
var data = JSON.parse(body);
console.log('data parsed.');
console.log('first team name: ' + data.teams[0].TeamName);
console.log(typeof data);
return data;
})
}).on('error', (e) => {
console.log(`Got error from Finhockey: ${e.message}`);
});
}
module.exports.getFinhockeyData = getFinhockeyData;
Up until now things work and the data object can be console.logged and its content is usable.
The router.js looks currently like this:
'use strict';
const express = require('express');
const async = require('async');
const router = express.Router();
const dataservice = require('./dataservice.js')
router.get('/', function(req, res) {
async.series([
function(callback) {
getFinhockeyData(callback)
}
],
function(err, results) {
console.log('start rendering');
res.render('index', { data: data });
})
});
module.exports = router;
When I run the app and refresh the / route, I can see from the console that the getFinhockeyData is called and the data object's content is available in dataservice.js's console.logs, but the browser window hangs and the res.render part is never reached.
I understand that the rendering should be done only after the endpoint data request has finished (async.series usage), but it seems that I lack a fundamental understanding on how to actually use the result data from the getFinhockeyData function in the main route.
Any advice on this? I'll be happy to provide more info if necessary.
Firstly, doing the request is asynchronous, so you'll have to use either a callback or a promise.
Even the async middleware won't let you just return data from an asynchronous call, it requires a callback, but using native promises seems easier here
const http = require('http');
getFinhockeyData = function() {
return new Promise( (resolve, reject) => {
http.get('http://tilastopalvelu.fi/ih/modules/mod_standings/helper/standings.php?statgroupid=3545', (res) => {
var body = "";
res.on('data', function(chunk) {
body += chunk;
});
res.on('end', function() {
resolve( JSON.parse(body) );
});
}).on('error', reject);
});
}
module.exports.getFinhockeyData = getFinhockeyData;
Also note that you're exporting as a module with a property
module.exports.getFinhockeyData = getFinhockeyData;
when you're going to use that in the routes, you have to use the property
const dataservice = require('./dataservice.js');
router.get('/', function(req, res) {
dataservice.getFinhockeyData().then(function(data) {
res.render('index', { data: JSON.stringify(data) });
}).catch(function(err) {
// epic fail, handle error here
});
});
You are responding to your route call with
res.render('index', { data: data });
But there is no data variable. It should be
res.render('index', { data: results });
Which is the variable where you are storing your data when it comes from the callback
The reason for res.render() not being called is, http requests are async. To get the response a callback must be passed, which you did but forgot to call it in the dataservice.js
This should help...
Change your dataservice.js like the following...
const http = require('http');
getFinhockeyData = function(callback) {
http.get('http://tilastopalvelu.fi/ih/modules/mod_standings/helper/standings.php?statgroupid=3545', (res) => {
console.log(`Got response: ${res.statusCode}`);
var body = "";
res.on('data', function (chunk) {
body += chunk;
})
res.on('end', function () {
var data = JSON.parse(body);
console.log('data parsed.');
console.log('first team name: ' + data.teams[0].TeamName);
console.log(typeof data);
callback(null, data); //returning the data to the callback
})
}).on('error', (e) => {
console.log(`Got error from Finhockey: ${e.message}`);
callback(e, null);
});
}
module.exports.getFinhockeyData = getFinhockeyData;
Change your router.js like the following...
router.get('/', function(req, res) {
async.series([
function(callback) {
getFinhockeyData(callback)
}
],
function(err, results) {
if(err === null){
console.log('start rendering');
res.render('index', { data: results[0] });
}
})
});
I'm banging my head for not learning from the basics and just jumping in.
I'm building an API that returns the SSL Certificate status of a domain.
It's working fine on console.log but the JSON output is empty, obviously because the exports get executed before the https request ends.
How do I incorporate the exports in response.on(end) function?
Thanks a lot!
function getSSL(domain) {
var options = {
host: 'www.'+domain+'.com',
method: 'get',
path: '/'
};
var isAuth = false;
callback = function(response) {
response.on('data', function () {
isAuth = response.socket.authorized;
});
response.on('end', function () {
console.log(isAuth);
});
}
var req = https.request(options, callback).end();
}
exports.findByDomain = function (req, response) {
var id = req.params.id;
sslCheck = getSSL(id);
response.send(sslCheck);
};
Yes, the response.send(sslCheck); gets executed before getSSL(id); has a chance to finish. You need to send in a callback so it can be executed after getSSL(id); finishes:
function getSSL(domain, callback) {
var options = {
host: 'www.'+domain+'.com',
method: 'get',
path: '/'
};
var isAuth = false;
var httpCallback = function(response) {
response.on('data', function () {
isAuth = response.socket.authorized;
});
response.on('end', function () {
console.log(isAuth);
callback(isAuth);
});
}
var req = https.request(options, httpCallback).end();
}
exports.findByDomain = function (req, response) {
var id = req.params.id;
getSSL(id, function(sslCheck) {
response.send(sslCheck);
});
};