I'm trying to query my mysql database for a value using Async/Await but my constant 'map' always returns undefined, I am not too sure why
const get_map = () =>{
db.query('SELECT game,game2 FROM battles WHERE player1=? OR player2=?',[result.char,result.char],(err,results)=>{
if(err){
return(err)
}
if(!results[0]){
return('No such battle?')
}
console.log(results[0])
return(results[0])
})
}
const proccessTurn = async ()=>{
const map = await get_map()
console.log(map)
let game = JSON.parse(map.game)
let game2 = JSON.parse(map.game2)
const char = result.char
const playerTurn = game2.turn[0]
}
The console doesn't even log
console.log(results[0])
This line so why does the await function resolve before it actually returns something? Shouldn't it wait for the returns?
Thank you for the help
As the mysql library doesn't support promises, you can use the promisify util function from Node.js like this:
const { promisify } = require('util');
const query = promisify(db.query).bind(db);
const get_map = async () => {
try {
const result = await query('SELECT game,game2 FROM battles WHERE player1=? OR player2=?',[result.char,result.char]);
if(!results[0]){
return 'No such battle?';
}
console.log(results[0])
return results[0];
}
catch(e) {
return e;
}
}
const proccessTurn = async ()=>{
const map = await get_map()
console.log(map)
let game = JSON.parse(map.game)
let game2 = JSON.parse(map.game2)
const char = result.char
const playerTurn = game2.turn[0]
}
The third parameter to db.query() is a callback. If you're returning anything in callback it's actually returned to the function itself, (db.query in this case). You're not returning anything from get_map(). So return a new promise from get_map like this,
const get_map = () =>{
return new Promise((resolve, reject) => {
db.query('SELECT game,game2 FROM battles WHERE player1=? OR player2=?',[result.char,result.char],(err,results)=>{
if(err){
reject(err)
}
if(!results[0]){
reject('No such battle?')
}
console.log(results[0])
resolve(results[0])
}
});
}
const proccessTurn = async ()=>{
const map = await get_map()
console.log(map)
let game = JSON.parse(map.game)
let game2 = JSON.parse(map.game2)
const char = result.char
const playerTurn = game2.turn[0]
});
Related
This question already has an answer here:
Getting Promise pending ..- ES6
(1 answer)
Closed 12 months ago.
When running the below code and dumping out the results variable it returns Promise {<pending>}, I have added the await key word to the being of the function call so const results = await getAllResults() however this returns the error of Unexpected reserved word 'await'.
Anyone have any ideas?
useEffect(() => {
async function getPageOfResults(page) {
const response = await axios.get('https://swapi.dev/api/starships/?page=' + page);
return response.data.results;
}
async function getAllResults() {
let starships = [];
let lastResultsLength = 10;
let page = 1;
while (lastResultsLength === 10) {
const newResults = await getPageOfResults(page);
page++;
lastResultsLength = newResults.length;
starships = starships.concat(newResults);
}
return starships;
}
const results = getAllResults();
}, []);
You need to add async in the useEffect like so:
useEffect(async () => {
async function getPageOfResults(page) {
const response = await axios.get('https://swapi.dev/api/starships/?page=' + page);
return response.data.results;
}
async function getAllResults() {
let starships = [];
let lastResultsLength = 10;
let page = 1;
while (lastResultsLength === 10) {
const newResults = await getPageOfResults(page);
page++;
lastResultsLength = newResults.length;
starships = starships.concat(newResults);
}
return starships;
}
const results = await getAllResults();
}, []);
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();
This is the code to fetch all the results from the website.
const puppeteer = require('puppeteer');
let students = [];
let rollPrefix = '387EA';
let regPrefix = 'EA87S18';
let currRoll = 80;
let currReg = 80;
let i = 0;
(async () => {
const browser = await puppeteer.launch({
headless: false, // Show the window for debugging
slowMo: 150 // slow down by 50ms
});
const page = await browser.newPage();
let rolltemp = rollPrefix + pad(currRoll,3);
let regTemp = regPrefix + pad(currReg,3);
while(i < 4){
await page.goto('http://orissaresults.nic.in/CHSE');
await page.type('#txtRollNo', rolltemp);
await page.type('#txtRegNo', regTemp);
const element = await page.$("#divCaptch");
const text = await (await element.getProperty('textContent')).jsonValue();
await page.type('#txt_UserCaptcha', text);
await page.click('#btnSubmit');
page.on('dialog', async (dialog) => {
await dialog.dismiss().catch(() => {
console.log(dialog.message());
return new Result(TestStatus.FAIL, dialog.message());
})})
try{
await page.waitForNavigation()
await page.waitForSelector('table');
const RollNO = await page.evaluate(() => {
return document.querySelectorAll('table')[2].rows[0].cells[1].innerText.trim();
});
const Name = await page.evaluate(() => {
return document.querySelectorAll('table')[2].rows[2].cells[1].innerText.trim();
});
const RegNo = await page.evaluate(() => {
return document.querySelectorAll('table')[2].rows[1].cells[1].innerText.trim();
});
const Total = await page.evaluate(() => {
return document.querySelectorAll('table')[3].rows[8].cells[0].innerText.trim();
});
let student = new Student(RollNO,Name,RegNo,Total)
students.push(student)
}catch{
currReg++;
continue;
}
currRoll++;
i++;
}
await browser.close()
// let json = JSON.stringify(students);
// storeData(json,'test.json')
})();
// function delay(time) {
// return new Promise(function(resolve) {
// setTimeout(resolve, time)
// });
// }
function pad(num, size) {
var s = num+"";
while (s.length < size) s = "0" + s;
return s;
}
class Student {
constructor(roll,name,reg,total){
this.roll = roll;
this.name = name;
this.reg = reg;
this.total = total;
}
}
const fs = require('fs')
const storeData = (data, path) => {
try {
fs.writeFileSync(path, data)
} catch (err) {
console.error(err)
}
}
Here the variable value of currReg stays the same pls help
The code tries each roll no and reg no combinations but there are some reg no that doesnt match with roll no so in the code the roll no should stay the same but the reg no should increase by one..
Not really sure what should happen with each combination, but here's an implementation which inputs all combinations. Below a short explanation:
const puppeteer = require('puppeteer');
let students = [];
(async () => {
const browser = await puppeteer.launch({
headless: false, // Show the window for debugging
slowMo: 150 // slow down by 50ms
});
const page = await browser.newPage();
let i = 0;
let j = 0;
const rollPrefix = '387EA';
const regPrefix = 'EA87S18';
let currRoll = 80;
let currReg = 80;
while(i < 4){
while(j < 4) {
let rolltemp = rollPrefix + pad(currRoll,3);
let regTemp = regPrefix + pad(currReg,3);
console.log("rolltemp = ", rolltemp, " regtemp = ", regTemp);
await page.goto('http://orissaresults.nic.in/CHSE');
await page.type('#txtRollNo', rolltemp);
await page.type('#txtRegNo', regTemp);
const element = await page.$("#divCaptch");
const text = await (await element.getProperty('textContent')).jsonValue();
await page.type('#txt_UserCaptcha', text);
await page.click('#btnSubmit');
page.on('dialog', async (dialog) => {
await dialog.dismiss().catch(() => {
console.log(dialog.message());
return new Result(TestStatus.FAIL, dialog.message());
})})
try{
await page.waitForNavigation()
await page.waitForSelector('table');
const RollNO = await page.evaluate(() => {
return document.querySelectorAll('table')[2].rows[0].cells[1].innerText.trim();
});
const Name = await page.evaluate(() => {
return document.querySelectorAll('table')[2].rows[2].cells[1].innerText.trim();
});
const RegNo = await page.evaluate(() => {
return document.querySelectorAll('table')[2].rows[1].cells[1].innerText.trim();
});
const Total = await page.evaluate(() => {
return document.querySelectorAll('table')[3].rows[8].cells[0].innerText.trim();
});
let student = new Student(RollNO,Name,RegNo,Total)
students.push(student)
} catch {
continue;
}
currReg++;
j++;
}
currReg = 80;
j = 0;
currRoll++;
i++;
}
await browser.close()
// let json = JSON.stringify(students);
// storeData(json,'test.json')
})();
// function delay(time) {
// return new Promise(function(resolve) {
// setTimeout(resolve, time)
// });
// }
function pad(num, size) {
var s = num+"";
while (s.length < size) s = "0" + s;
return s;
}
class Student {
constructor(roll,name,reg,total){
this.roll = roll;
this.name = name;
this.reg = reg;
this.total = total;
}
}
const fs = require('fs')
const storeData = (data, path) => {
try {
fs.writeFileSync(path, data)
} catch (err) {
console.error(err)
}
}
Explanation
so, assuming you want all combinations of pairs {currentRol, currentReg}, you'll definitely need two loops. There are gonna be 4x4=16 combinations in total (I assume, basing on i < 4 condition). First mistake which you made was assigning regTemp before while loop, effectively not changing the strings entered to the inputs, only some unused, temporary values (currentRoll, currentReg). So, first and foremost is to move rollTemp and regTemp definitions into the while loop. Now, as I said, you're gonna need two nested loops, as you need to generate all possible combinations (for each currentRol, all currentRegs). One more thing to remember is that you'll have to reset currentReg with each outer loop iteration, as you want to test each reg for given roll.
Note about variables' scopes
This is a great example why variables scopes are critical when programming. Not only it increases readability and comprehensibility of the given code - it prevents other functions/scopes from using symbols which do not really belong to them. Please notice where the variables definitions are within my snippet. Probably it's not perfect, but why would you pollute global namespace as in your example?
So basically im working on a cron job in my app that fires every 3 hours and updating users 'score' by calling the RiotApi
basically the function so far
exports.updatePlayersPoints = async () => {
console.log('STARTED UPDATING');
try {
const players = await UserLadder.findAll();
await Promise.all(
players.map(async (player) => {
const p = await RiotAccount.findOne({
where: {
userId: player.userId,
},
include: RiotRegions,
});
const beginTime = new Date(player.dataValues.createdAt);
let data;
try {
const res = await axios.get(
`https://${
p.dataValues.riot_region.dataValues.name
}.api.riotgames.com/lol/match/v4/matchlists/by-account/${
p.dataValues.accountId
}?queue=420&beginTime=${beginTime.getTime()}&api_key=${
process.env.RIOT_KEY
}`
);
data = res.data;
} catch (error) {
if (!error.response.status === 404) {
console.error(error);
}
}
if (!data) {
return;
}
let totalScore = player.dataValues.userPoints;
await Promise.all(
data.matches.map(async (match, i) => {
if (i < 15) {
const { data } = await axios.get(
`https://${p.dataValues.riot_region.dataValues.name}.api.riotgames.com/lol/match/v4/matches/${match.gameId}?api_key=${process.env.RIOT_KEY}`
);
const calculateScore = () => {
return new Promise((resolve) => {
const { stats } = _.find(
data.participants,
(o) => o.championId === match.champion
);
const killsPts = stats.kills * 2;
const deathPts = stats.deaths * -1.5;
const assistsPts = stats.assists;
const wardsPts = stats.wardsPlaced / 4;
const firstBloodPts = stats.firstBloodKill ? 3 : 0;
const firstBloodAssistPts = stats.firstBloodAssist ? 3 : 0;
const firstTowerPts = stats.firstTowerKill ? 2 : 0;
const firstTowerAssistPts = stats.firstTowerAssist ? 2 : 0;
const score =
killsPts +
deathPts +
assistsPts +
wardsPts +
firstBloodPts +
firstBloodAssistPts +
firstTowerPts +
firstTowerAssistPts;
totalScore += score;
resolve();
});
};
await calculateScore();
}
})
);
const user = await UserLadder.findOne({
where: {
userId: player.userId,
},
});
user.userPoints = parseFloat(totalScore);
user.lastGameId = data.matches[0].gameId;
await user.save();
})
);
console.log('FINISHED UPDATING');
} catch (error) {
console.error(error);
}
};
Basically it just looks up the table userladder to find the players that are signed to the ladder and for each one of these players it fires a map function that makes a request to the riotapi to get the match history of this player and then later make an inside map function to map each one of these matches.
but basically I updated it to now keep track of the game id of the last call before 3 hours so it doesn't have to make request that was already done.
user.lastGameId = data.matches[0].gameId;
but now in my second map function that maps the matches I wasn't it so that if the last game from my database matches the game id that currently being mapped I want to stop the map function and not continue this record or the ones after because it also means they all have been already counted.
but I can not seem to find a way to do it.
i tried using break; but it didn't work
any ideas?
using for loop
I tried a small test with for loop so I tried
for (let i = 0; i < 15; i++) {
await new Promise(async (resolve, reject) => {
const match = data.matches[i];
console.log(match);
resolve();
if (i === 1) {
break;
}
});
}
but I still go the same error
SyntaxError: Illegal break statement
Instead of trying to "break" a map, you should filter the matches that you want to process before you execute the map.
Something like this:
await Promise.all(
const filteredMatches = data.matches.filter(match => match.gameId > previousId);
filteredMatches.map(async (match, i) => { ...
More on filter() in javascript.
Edit: If generated id's are random and are not ordered, you can store all previous id's in a Set, and then just ask if it has been previously added
await Promise.all(
const filteredMatches = data.matches.filter(match => mySet.has(match.gameId));
filteredMatches.map(async (match, i) => { ...
More on Set in javascript.
I have 2 file, main.js and input.js.
In input.js I prompt the user to give me an interval in '1-10'(string) format. Later I cut this string and get the 2 numbers from it and check if the numbers are correct or not:
let getInput = () => {
return new Promise(function (resolve, reject) {
readline.question(`Give me interval (e.g.: 1-10).\n`, (input) => {
let fields = input.split('-');
let startNumber = Number(fields[0]);
let endNumber = Number(fields[1]);
if ((startNumber) && (endNumber) && (startNumber > 0) && (endNumber >= startNumber)) {
console.log(`ok`);
readline.close()
resolve([startNumber, endNumber]);
} else {
reject('not ok');
getInput();
}
});
});
}
In main.js I call this function asyncronously and I save it's result to a variable:
let intervalArray = await getInput();
.
.
.
someotherstuff
My problem is if I provide wrong input (for example '0-1' or '10-9' or '-10')
I got an UnhandledPromise error so the code won't execute more.
My goal would be when the user gives wrong input, 'not ok, give me another' should appear in console, and the program should wait for another input. If that input is correct, continue the execution. If not, the program should ask another input.
How could I achieve this?
EDIT:
Here are the full codes.
Input.js:
const readline = require('readline').createInterface({
input: process.stdin,
output: process.stdout
});
let getInput = () => {
return new Promise(function (resolve, reject) {
readline.question(`tol-ig formatumban (pl.: 1-10).\n`, (data) => {
let fields = data.split('-');
let startNumber = Number(fields[0]);
let endNumber = Number(fields[1]);
if ((startNumber) && (endNumber) && (startNumber > 0) && (endNumber >= startNumber)) {
console.log(`Kereses inditasa ${startNumber}-${endNumber} oldalakon.`);
readline.close()
resolve([startNumber, endNumber]);
} else {
readline.close();
reject(new Error('not ok'));
}
});
});
}
module.exports.getInput = getInput;
And main.js:
const puppeteer = require('puppeteer');
const { getInput } = require('./input');
const { mouseMovements } = require('./mouse');
const { tuneUserAgent } = require('./userAgent');
async function listItems() {
let intervalArray = null;
while (intervalArray === null) {
try {
let intervalArray = await getInput();
} catch (err) {
// write to user not ok
}
}
const browser = await puppeteer.launch({ headless: false });
const context = await browser.createIncognitoBrowserContext();
const page = await context.newPage();
const extractPartners = async url => {
const page = await context.newPage();
await tuneUserAgent(page);
await page.goto(url, { waitUntil: 'load' });
await page.waitFor(Math.round(Math.random() * 500) + 500);
await mouseMovements(page);
const partnersOnPage = await page.evaluate(() =>
Array.from(document.querySelectorAll("div.compact"))
.map(compact => (compact.querySelector(".logo a").href.slice(-16))));
await page.close();
const nextPageNumber = parseInt(url.match(/page=(\d+)$/)[1], 10) + 1;
if (nextPageNumber > endPage) {
console.log(`Terminate recursion on: ${url}`);
return partnersOnPage;
} else {
console.log(`Scraped: ${url}`);
const nextUrl = `https://marketingplatform.google.com/about/partners/find-a-partner?page=${nextPageNumber}`;
let randomWait = (Math.round(Math.random() * 2000) + 1000);
await page.waitFor(randomWait);
return partnersOnPage.concat(await extractPartners(nextUrl));
}
};
let startPage = intervalArray[0];
let endPage = intervalArray[1];
const firstUrl =
`https://marketingplatform.google.com/about/partners/find-a-partner?page=${startPage}`;
const partners = await extractPartners(firstUrl);
await browser.close();
return Promise.resolve(partners);
};
module.exports.listItems = listItems;
You have to handle the error. As you are using await, the easiest is to use try catch.
try {
let intervalArray = await getInput();
} catch (err) {
// write to user not ok
}
You can wrap it in cycle to keep requesting user for new inputs.
let intervalArray = null;
while (intervalArray === null) {
try {
let intervalArray = await getInput();
} catch (err) {
// write to user not ok
}
}
^^ Remember to remove getInput(); from the else part of your new Promise. Maybe you will also need to close the readline as you will open it again. Also rejection is similar to throwing an error and you should always send Error-based object there.
} else {
readline.close();
reject(new Error('not ok'));
}
EDIT: after your update I created POC. The readline.close() should not be there actually (looks its one time use only), but this POC looks fine:
toBeRequired.js
const readline = require('readline').createInterface({
input: process.stdin,
output: process.stdout
});
let getInput = () => {
return new Promise(function (resolve, reject) {
readline.question(`tol-ig formatumban (pl.: 1-10).\n`, (data) => {
let fields = data.split('-');
let startNumber = Number(fields[0]);
let endNumber = Number(fields[1]);
if ((startNumber) && (endNumber) && (startNumber > 0) && (endNumber >= startNumber)) {
console.log(`Kereses inditasa ${startNumber}-${endNumber} oldalakon.`);
readline.close()
resolve([startNumber, endNumber]);
} else {
reject(new Error('not ok'));
}
});
});
}
module.exports.getInput = getInput;
server.js
const a = require('./toBeRequired');
async function x() {
let input = null;
while (input === null) {
try {
input = await a.getInput();
} catch (err) {
console.log('nooo');
}
}
}
x();
Create these two files in same folder and run node server.js