On my Node JS backend I run this method.
var locations = [];
exports.constructionsiteParser = function constructionsiteParser(response){
var timestamp = new Date().toDateInputValue();
const $ = cheerio.load(response);
$('situation').each( function(){
var situation = [];
$(this).find('situationRecord').each( function(i){
var startLocationCode = $(this).find('alertCMethod2SecondaryPointLocation').find('specificLocation').text();
var endLocationCode = $(this).find('alertCMethod2PrimaryPointLocation').find('specificLocation').text();
var overallStartTime = $(this).find('overallStartTime').text();
var overallEndTime = $(this).find('overallEndTime').text();
if((startLocationCode != '') && new Date(timestamp) >= new Date(overallStartTime) && new Date(timestamp) <= new Date(overallEndTime) ){
Promise.all([
locationCodeToGeodataRequst.geodataByLocationcode(startLocationCode),
locationCodeToGeodataRequst.geodataByLocationcode(endLocationCode)
]).then( values =>{
return createSituationRecord($, this, startLocationCode, endLocationCode, values[0], values[1]);
}).then( function(obj){
console.log("before push", situation);
situation.push(obj);
console.log("after push", situation);
return situation;
}, handleError);
}
})
console.log("from outter", situation.length);
if(situation.length > 0){ //if situation is not empty
locations.push(situation);
}
})
console.log(locations);
}
The console.log("from outter", situation.length); at the bottom prints always 0
also the console.log(locations) is empty
This is a part of the log:
...
from outter 0
from outter 0
from outter 0
from outter 0
from outter 0
[]
before push []
after push [....
I think this happens because the node server runs the bottom part before the inner each loop finishes. So I want to make it more snychronized. What I want to do is something like:
outer each{
//run this first
inner each{
.....
}
//if inner each is done run this
if(...){}
}
But I don't know how to put this in the correct syntax.
I have tried it with nested Promises but it doesn't work.
you can return this promise. deal it at caller
You can make use of async.eachOf(). I took a different approach in making your code synchronous. Hope it helps you.
'use strict';
let locations = [];
exports.constructionsiteParser = function constructionsiteParser(response) {
const $ = cheerio.load(response);
$('situation').each(function () {
let situation = [];
async.eachOf($(this).find('situationRecord'), function (value, key, callback) {
innerLoop(callback);
}, function (err, situation) {
if (err) {
return console.error(err.message);
}
console.log("from outter", situation.length);
// this will run only if the inner loops completes
if (situation.length > 0) { //if situation is not empty
locations.push(situation);
}
});
});
console.log(locations);
};
function innerLoop(callback) {
let startLocationCode = $(this).find('alertCMethod2SecondaryPointLocation').find('specificLocation').text();
let endLocationCode = $(this).find('alertCMethod2PrimaryPointLocation').find('specificLocation').text();
let overallStartTime = $(this).find('overallStartTime').text();
let overallEndTime = $(this).find('overallEndTime').text();
if (isInvalid(startLocationCode, overallStartTime, overallEndTime)) {
return callback('some error msg');
}
Promise.all([
locationCodeToGeodataRequst.geodataByLocationcode(startLocationCode),
locationCodeToGeodataRequst.geodataByLocationcode(endLocationCode)
]).then(values => {
return createSituationRecord($, this, startLocationCode, endLocationCode, values[0], values[1]);
}).then((obj) => {
return callback(null, obj);
}).catch((err) => {
console.log('err', err.stack);
return callback(err);
});
}
function isInvalid(startLocationCode, startTime, endTime) {
let timestamp = new Date().toDateInputValue();
let isEmptyCode = startLocationCode === '';
let isYetToStart = new Date(timestamp) < new Date(startTime);
let isOver = new Date(timestamp) > new Date(endTime);
return isEmptyCode || isYetToStart || isOver;
}
You should take a deeper look into promises because they are the way to go for synchronous operations. Maybe try to merge your code into functions.
Related
I am doing some practice in node.js. In this exercise I been asked to find a country name through a GET Http Request to an endpoint passing a page integer as a parameter.
Where the important response structs are these {page, total_pages, data}.
page is the current page,
total_pages is the last page,
data is an array of 10 country object.
In getCountryName func I am able to retrieve the right answer only if the answer is on the 1st page, the 1 iteration of the loop. So, why the loop only happens once?
Aditional, I wanted to retrieve the total_pages to replace the hardcode '25' value but I do not figure it out how to return it along with the search.
Any hint you wanna give me? The whole problem is in getCountryCode func.
'use strict';
const { Console } = require('console');
const https = require('https');
function makeRequest(page){
return new Promise(resolve => {
let obj='';
https.get('https://jsonmock.hackerrank.com/api/countries?page='+page, res => {
let data ='';
res.on('data',function(chunk){
data+=chunk;
});
res.on('end',function(){
obj=JSON.parse(data);
resolve(obj);
});
});
});
}
async function getCountryName(code) {
var res = '';
var pages = 25;
var i = 1;
while(i <= pages && res == ''){
console.log(i);
res = makeRequest(i)
.then(data => {
let f = ''
let p = data['total_pages'];
let search = data['data'].find(o => o.alpha3Code === code);
f = search != null ? search['name'] : f;
return f;
});
i++;
}
return res;
}
async function main() {
const name = await getCountryName('ARG');
console.log(`${name}\n`);
}
main();
Without modifying your code too much, this is how you do it:
'use strict';
const { Console } = require('console');
const https = require('https');
function makeRequest(page){
return new Promise(resolve => {
let obj='';
https.get('https://jsonmock.hackerrank.com/api/countries?page='+page, res => {
let data ='';
res.on('data',function(chunk){
data+=chunk;
});
res.on('end',function(){
obj=JSON.parse(data);
resolve(obj);
});
});
});
}
async function getCountryName(code) {
const pages = 25;
var i = 1;
let f = null
while(i <= pages && f === null){
console.log(i);
const data = await makeRequest(i) // put in try/catch
const p = data['total_pages'];
const search = data['data'].find(o => o.alpha3Code === code);
f = search !== null ? search['name'] : null;
i++;
}
return res;
}
async function main() {
const name = await getCountryName('ARG');
console.log(`${name}\n`);
}
main();
I am trying to trigger an another function in Firebase Cloud function with javascript. But i always getting an error of Can't set headers after they are sent. Please take a look at my code below: ................. ................. ............ ................ ................. ............... ....................... .................. ..............
exports.productIndexShuffleOne = functions.https.onRequest(async (req, res) => {
const interval = req.query.interval;
console.log("interval: "+interval);
const productRef = admin.firestore().collection("Products");
const adminRef = admin.firestore().collection("Admin").doc("totalProd").get();
const dateRef = admin.firestore().collection("Admin").doc("totalProd").collection("indexShuffle").doc("productShuffle").get();
return dateRef.then(documentSnapshot => {
const setDate = documentSnapshot.get('date').seconds;
var nextDay = setDate;
console.log("Date: "+nextDay);
const x = setInterval(function() {
clearInterval(x);
return Promise.all([adminRef]).then(result => {
const totalNum = result[0].data().totalNumber;
console.log("totalNum: "+totalNum);
var numberList = [];
var index = 1;
while(index <= totalNum){
numberList.push(index);
index++;
}
var cidx, ridx, tmp;
cidx = numberList.length;
while (cidx !== 0) {
ridx = Math.floor(Math.random() * cidx);
cidx--;
tmp = numberList[cidx];
numberList[cidx] = numberList[ridx];
numberList[ridx] = tmp;
}
console.log(numberList);
var counter = 0;
return productRef.get().then(snapshot => {
snapshot.forEach(doc => {
const prodID = doc.get('productID');
const index = doc.get('index');
var newIndex = numberList[counter];
counter++;
console.log("oldIndex: "+index);
console.log("newIndex: "+newIndex);
productRef.doc(prodID).update({
index: newIndex
}, {merge: true});
});
return res.redirect('https://us-central1-myfunction-123456.cloudfunctions.net/productIndexShuffleTwo?interval='+interval);
})
.catch(err => {
console.log('Error getting documents', err);
});
});
}, interval);
return res.status(203).send(interval);
}).catch(function(err) {
console.error(err);
});
});
This is because you've sent multiple responses while the rule is that you only allowed sending one response. Please try to look at your code and optimize it in such a way that it contains only one response.
I can see you have multiple responses as below:
1 -> return res.redirect('https://us-central1-myfunction-123456.cloudfunctions.net/productIndexShuffleTwo?interval='+interval);
2 -> return res.status(203).send(interval);
I believe that you can have res.redirect and then res.status.send called one after another. When you writing endpoints there rule of a thumb: always send response and only do that once. Refactor your code so there no way you can make those two calls, but only one of them.
I am trying to read some data from 2 different tables and parse a CSV file before rendering an ejs file.
I can get the data from both tables and from the CSV file but I seem to be unable to return the result.
Pretty sure this is a problem with the way I handle async execution but I fail to see what I am doing wrong.
I've spent the last 2 days reading about this (including the threads around here) and browsing but somehow the answer still escapes me.
First file - usercms.js
app.get('/userscms', function(req, res)
{
existingUsers.getExistingUsers()
.then(function(appUsers)
{
//global users array
//I can display these in my ejs file
globalAppUsers = appUsers;
})
.then(existingUsersAttributesQlik.getExistingUsersAttributesQlik())
.then(function(usersQlikAttributes)
{
//global user attributes array
//undefined data
globalUsersQlikAttributes = usersQlikAttributes;
})
.then(existingSuppliers.parseSuppliersCSV())
.then(function(supplierData)
{
//the result I am expecting
//this prints undefined
console.log(supplierData);
}).then(function()
{
res.render('userscms.ejs',
{
users: globalAppUsers,
attributes: globalUsersQlikAttributes
});
});
});
Second function - getxistingUsers.js (identical to the getExistingUsersAttributesQlik, except for the query)
var userData = [];
var appUsers = [];
(function (exports)
{
exports.getExistingUsers = function ()
{
return promisemysql.createConnection(dbconfig.development).then(function(conn)
{
var result = conn.query("SELECT id, username, firstName, lastName, email, phone, lastLogin, isAdmin, isValid, isPhoneValid, accountCreationDateTime FROM Users");
conn.end();
return result;
}).then(function(rows)
{
return rows;
}).then(function(rows)
{
if (rows.length)
{
userData = [];
appUsers = [];
rows.forEach(function (elem)
{
userData.push(_.toArray(elem));
});
for (i = 0; i < userData.length; i++)
{
var appUser = new appUserModel.AppUser(
userData[i][0],
userData[i][1],
userData[i][2],
userData[i][3],
userData[i][4],
userData[i][5],
userData[i][6],
userData[i][7],
userData[i][8],
userData[i][9],
userData[i][10]);
appUsers.push(_.toArray(appUser));
}
return appUsers;
}
else
{
console.log("NOPE");
return null;
}
}).then(function(appUsers)
{
console.log(appUsers);
return appUsers;
});
};
})(typeof exports === 'undefined' ? this['getExistingUsers'] = {} : exports);
Third file - parseSuppliersCSV.js
var supplierData = [];
var suppliersData = [];
var csvCount = 0;
(function (exports)
{
exports.parseSuppliersCSV = function ()
{
return new Promise(function(resolve, reject)
{
var fileStream = fs.createReadStream("myCSV.csv");
var parser = fastCsv();
csvCount = 0;
supplierData = [];
suppliersData = [];
fileStream
.on("readable", function ()
{
var data;
while ((data = fileStream.read()) !== null)
{
parser.write(data);
}
})
.on("end", function ()
{
parser.end();
});
parser
.on("readable", function ()
{
var data;
while ((data = parser.read()) !== null)
{
if(csvCount >= 1)
{
csvCount++;
var arrayOfStrings = data[0].split(';');
var supplier = new supplierModel.Supplier(arrayOfStrings[0],arrayOfStrings[1]);
suppliersData.push(_.toArray(supplier));
}
else
{
csvCount++;
}
}
})
.on("end", function ()
{
console.log("done");
//all OK here
console.log(suppliersData);
//this doesn't seem to return anything
return suppliersData;
});
});
};
})(typeof exports === 'undefined' ? this['parseSuppliersCSV'] = {} : exports);
Any ideas what I am doing wrong? Am I approaching this the wrong way?
I'll take a guess here and assume the promise you created should resolve to something...instead of returning a value.
.on("end", function ()
{
console.log("done");
//all OK here
console.log(suppliersData);
//this doesn't seem to return anything
return resolve(suppliersData);
});
i having Api Call which execute in For Loop some of the value which returns 10 sec itself some may take nearly 60 sec i have to maintain proper Timeout and clear session (i.e if results comes at 15 sec means it should goes to next input values and run the code) but currenly its waiting for 45 sec each single record how to optimize it
here my sample code :
if (selectedrows.length >= 1) {
for (var i = 0; i < selectedrows.length; i++) {
var myVar = setTimeout (function (k) {
var ob = { results: "Appending ..." };
child.update(selectedrows[k][4], selectedrows[k][4], ob);
var fullName = selectedrows[k][1] + ' ' + selectedrows[k][2];
math.ResultCall.async(fullName,function (err, res) {
if (err) throw err;
var returnedValue = JSON.parse(res);
console.log(returnedValue);
if(returnedValue.Result == null || returnedValue.Result.FOUND_Result == null)
{
console.log("None found")
}
else{
var obj = { results: “res” };
child.update(selectedrows[k][4], selectedrows[k][4], obj);
}
}
});
}, i * 45000,i);
}
}
Rephrasing your question, you need to return the data when your api gets resolved.
For this please go through https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/resolve
JavaScript, by default it work asynchronously because of its event loop.
You have promises and resolve to get notified when your api returns a data
Hope I helped :)
There are several approaches to implement the solution
1. Async-Await: in-case the records-processing order is important
for( let i=0; i<selectedrows.length; i++)
{
let ob = { results: "Appending ..." };
child.update(selectedrows[i][4], selectedrows[i][4], ob);
let fullName = selectedrows[i][1] + ' ' + selectedrows[i][2];
await new Promise((resolve,reject)=>
{
math.ResultCall.async(fullName,(err, res) => {
if (err) reject(err);
let returnedValue = JSON.parse(res);
console.log(returnedValue);
if(returnedValue.Result == null || returnedValue.Result.FOUND_Result == null) {
console.log("None found")
} else {
let obj = { results: “res” };
child.update(selectedrows[i][4], selectedrows[i][4], obj);
}
resolve();
});
}
**don't forget this means the wrapping function should be async as well (which returns a promise that can be resolved if necessary)
2.Promise.All: if the order is not important
let promArray = [];
for( let i=0; i<selectedrows.length; i++)
{
let ob = { results: "Appending ..." };
child.update(selectedrows[i][4], selectedrows[i][4], ob);
let fullName = selectedrows[i][1] + ' ' + selectedrows[i][2];
promArray.push( new Promise((resolve,reject)=>
{
math.ResultCall.async(fullName,(err, res) => {
if (err) reject(err);
let returnedValue = JSON.parse(res);
console.log(returnedValue);
if(returnedValue.Result == null || returnedValue.Result.FOUND_Result == null) {
console.log("None found")
} else {
let obj = { results: “res” };
child.update(selectedrows[i][4], selectedrows[i][4], obj);
}
resolve();
});
);
}
Promise.all(promArray);
** this will also return a Promise that can be resolved if necessary.
In getNestedFlags I'm adding values to finalJson array.
Then after console.log I can see entire finalJson array with values but resolve returns an empty array. Do you know how to achive the same result in resolve as in console.log?
getScheduledFlags: (idTc, idScheduled) => {
return new Promise((resolve, reject) => {
var getNestedFlags = (array1, array2, res) => {
array1.forEach(item => {
var childrenItems = res.filter(item1 => item1.id_parent == item.id)
if(childrenItems.length > 1){
var childrens = []
getNestedFlags(childrenItems, childrens, res)
array2[item.name] = childrens
} else {
array2[item.name] = item.value
}
})
}
_tc.get(idTc).then(result => {
var flags = result.flags
var bases = result.bases
_featureFlags.getAll().then(allFlags => {
tcScheduled= _featureFlags.getFinalTcFlags(result)
res = _this.replaceFlags(allFlags, tcScheduled.flags)
parentFlags = res.filter(item => item.id_parent == 0)
var finalJson = []
getNestedFlags(parentFlags, finalJson, res)
console.log(finalJson)
resolve(finalJson)
})
})
})
},
The code which you have posted must work as array is passed by reference rather than value in javascript. Check both the console.log() in the code before and after the call to resolve() function.
var finalJson = []
var parentFlags ='';
var res ='';
getNestedFlags(parentFlags, finalJson, res);
console.log(finalJson);
resolve(finalJson);
console.log(finalJson);
function getNestedFlags(parentFlags, finalJson, res){
finalJson.push(1);
finalJson.push(2);
finalJson.push(3);
}
function resolve(finalJson){
finalJson.push(4);
finalJson.push(5);
}
Initializing array by [] was my problem.
Now with {} everything is fine.