The problem is with the promises and the async function. "All moved" is supposed to be logged after everything in async.each is done. But nothing is ever logged.
Here is my exports functions:
var courier_id = data.ref.parent.key;
return admin.database().ref("firewall_queue/"+courier_id+"/orders").once('value',function(orders){
//console.log(Object.keys(orders.val()));
async.each(Object.keys(orders.val()), function (order, callback) {
if(order != "none") {
return moveToWaitingFromFirewall(order).then(callback())
}
},
function (err) {
console.log("All moved");
return admin.database().ref("/firewall_queue/"+courier_id+"/orders/").remove().then(()=>{
return pushToPending(courier_id,data.ref.key);
})
});
})
Here is my moveToWaitingFromFirewall function:
function moveToWaitingFromFirewall(order_id){
var order = {};
order.id = order_id;
var promises = [];
promises.push(new Promise((resolve) => {
admin.database().ref("orders/"+order_id+"/zone").once('value').then(function(zone){
order.zone = zone.val();
resolve();
})
}))
promises.push(new Promise((resolve) => {
admin.database().ref("orders/"+order_id+"/time_order_placed").once('value').then(function(time_order_placed){
order.time = time_order_placed.val();
resolve();
})
}))
//grab zone and time first
return Promise.all(promises).then(()=>{
return admin.database().ref(order.zone+"/wait_order_queue/"+order.id).set(order.time);
})
}
JSON Firebase
"c98" : {
"orders" : {
"0333" : 123123,
"0345" : 12,
"0911" : 123,
"none" : "none"
}
Study this a little bit, and maybe apply to your current code.
Imagine admin.database().ref("orders/"+order_id+"/time_order_placed").once('value') is like delay(time)
// let delay = time => new Promise(res=>setTimeout(res,time));
let delay = function(time){
return new Promise(function(resolve,reject){
setTimeout(function(){
resolve();
},time);
});
}
let myPromise = function(order){
return Promise.all([
delay(500),
delay(500),
delay(1000).then(function(){
console.log('Order complete: ',order);
return; // returns undefined, so cb doesn't pass anything to cb(err), but use ()=>cb() to avoid this anyways.
})
]);
}
let orders = [1,2,3];
async.each(orders,function(order,cb){
myPromise(order)
.then(()=>cb())
.catch(err=>cb(err));
},function(err,data){
if(err){
console.log('Err',err);
}else{
console.log('all Finished');
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/async/2.6.0/async.js"></script>
Related
Im trying to return the value from a python script from a nodejs child process and i just cant seem to get it to work, it prints in the console using console.log correctly as it should but only returns undefined, i was wondering if there is a way to directly return that value, or to parse the console.log results into a string.
var sys = require('util');
module.exports = function() {
this.getPlay = function getPlaylist(name) {
const childPython = spawn('python' ,['main.py', name]);
var result = '';
childPython.stdout.on(`data` , (data) => {
result += data.toString();
});
childPython.on('exit' , () => {
console.log(result);
});
}};
Python script is empty for now and prints "Hello 'name' "
Edit:
I tried to use promises and here is what i have:
(async function(){
function test(name) {
return new Promise((resolve , reject) => {
const childPython = spawn('python' ,['main.py', "He"]);
var result = '';
childPython.stdout.on(`data` , (data) => {
result += data.toString();
});
childPython.on('close' , function(code) {
t = result
resolve(result)
});
childPython.on('error' , function(err){
reject(err)
});
})};
var t;
await test(name);
console.log(t);
return t;
})();
Define it like this.
function getPlaylist(name) {
return new Promise((resolve , reject) => {
const childPython = spawn('python' ,['main.py', name]);
var result = '';
childPython.stdout.on(`data` , (data) => {
result += data.toString();
});
childPython.on('close' , function(code) {
resolve(result)
});
childPython.on('error' , function(err){
reject(err)
});
})
};
Remeber to use try...catch for it it gets rejected. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/try...catch
async function runTest() {
try {
const playList = await getPlaylist();
console.log(playList);
} catch (err) {
}
}
runTest()
const {spawn} = require('child_process');
const getPythonScriptStdout = (pythonScriptPath) => {
const python = spawn('python', [pythonScriptPath]);
return new Promise((resolve, reject) => {
let result = ""
python.stdout.on('data', (data) => {
result += data
});
python.on('close', () => {
resolve(result)
});
python.on('error', (err) => {
reject(err)
});
})
}
getPythonScriptStdout('./python.py').then((output) => {
console.log(output)
})
python.py file
print("hi from python")
When i create new variable and assign callback function, But data cannot return from callback function. Undefined is occurring at new variable.
const nedb = require('nedb');
const user = new nedb({ filename: './builds/database/users.db', autoload: true });
var s = user.find({}, function (err,docs) {
if(docs.length == 0) {
var data = false;
} else {
var data = docs;
}
return data;
});
console.log(s);
var s is undefined! ....
You are mixing up callback and Promise which are two different way to handle asynchronous calls.
I recommend you to use of Promises because they are simpler and the present and future of javascript.
Using async/await which is the next step after Promises
const user = {
find: () => ['jon', 'kalessi', 'jorah'],
};
async function getUsers() {
return (await user.find({})) || [];
}
async function myJob() {
const users = await getUsers();
console.log(users);
// Put your next code here
}
myJob();
Full promise :
const user = {
find: () => new Promise((resolve) => resolve(['jon', 'kalessi', 'jorah'])),
};
user.find({})
.then((docs = []) => {
console.log(docs);
// Put you next code here, you can use of the variable docs
})
.catch((err) => {
console.log(err);
});
Full callback :
const user = {
find: (_, callback) => callback(false, ['jon', 'kalessi', 'jorah']),
};
user.find({}, (err, docs = []) => {
if (err) {
console.log(err);
} else {
console.log(docs);
// Put you next code here, you can use of the variable docs
}
});
I think user.find returning the promise. you can do like this.
const nedb = require('nedb');
const user = new nedb({ filename: './builds/database/users.db', autoload: true });
var s = user.find({}, function (err,docs) {
if(docs.length == 0) {
var data = false;
} else {
var data = docs;
}
return data;
});
Promise.all(s)
.then(result => {
console.log(result);
});
Otherwise you can also use await Like this:
async function abc(){
const nedb = require('nedb');
const user = new nedb({ filename: './builds/database/users.db', autoload: true });
var s = await user.find({}, function (err,docs) {
if(docs.length == 0) {
var data = false;
} else {
var data = docs;
}
return data;
});
}
because await worked with async thats why i put it into async function.
I have some problems with the multiple promises in my code. There is no way to return to items who are not in the database. I changed the code multiple times but no luck. The only data it returns is "datas": [
null,
null
]
This is my code
var start = function(offset, entry) {
return new Promise(function(resolve, reject) {
rp('************' + entry).then(function(repos) {
resolve(repos);
}).catch(function(err) {
reject(err);
});
});
};
var findnewones = function(iten) {
return new Promise(function(resolve, reject) {
return Promise.all(iten.items.map(function(ndtrcitem) {
return new Promise(function(resolve, reject) {
Items.findOne({"metadata.trcid": ndtrcitem.metadata.trcid}).exec(function(err, doc) {
if (!doc) {
resolve(ndtrcitem);
}
});
})
})).then(datas => {
resolve(datas);
});
})
}
exports.find = function(req, res, next) {
var ndite = ["locations", "events"];
var items = [];
return Promise.all(ndite.map(function(entry) {
return start(0, entry).then(function(res) {
for (i = 0; i <= res.count; i += 10) {
return start(i, entry).then(function(iten) {
findnewones(iten).then(function(dat) {
items.push(dat);
});
});
}
return items;
})
})).then(datas => {
res.json({datas});
});
}
I think because the for loop there is synchronous and it's not waiting for the start() promise to resolve.
for (i = 0; i <= res.count; i += 10) {
return start(i, entry).then(function(iten) {
findnewones(iten).then(function(dat) {
items.push(dat);
});
});
}
I have replaced it with async/await, don't know if it will work right away, I am just providing you with a hint in this very complicated promise chain. If it or any variation of it works please update this answer.
exports.find = function (req, res, next) {
var ndite = ["locations", "events"];
var items = [];
return Promise.all(ndite.map(function (entry) {
return start(0, entry)
.then(async function (res) {////// this
for (i = 0; i <= res.count; i += 10) {
await start(i, entry).then(function (iten) { ////this
findnewones(iten).then(function (dat) {
items.push(dat);
});
});
}
return items;
})
})).then(datas => {
res.json({
datas
});
});
}
I've created nodejs to trigger(with cronjobs) firebase realtime database as follow:
var db = admin.database();
var ref = db.ref('myusers');
var promises = [];
function updateUnlocked(isLocked, locked, msisdn) {
return new Promise(function (resolve, reject) {
if (isLocked === 1) {
var startDate = moment(locked);
var endDate = moment();
var result = endDate.diff(startDate, 'minutes');
if (result > 5) {
var ref = db.ref('myusers/' + msisdn);
ref.update({isLocked: 2});
}
}
resolve('done');
});
}
ref.once('value', function(snapshot) {
snapshot.forEach(childSnapshot => {
promises.push(updateUnlocked(childSnapshot.val().isLocked, childSnapshot.val().locked, childSnapshot.key));
});
});
Promise.all(promises).then(function(data) {
console.log(data);
}).catch(function(err) {
console.log('error');
});
Please let me know where can I add process.exit(). Thanks.
You must wait for the "once" callback to get executed. Else the promise array is empty and the process could exit immediately.
var db = admin.database();
var ref = db.ref('myusers');
function updateUnlocked(isLocked, locked, msisdn) {
...
}
ref.once('value', function(snapshot) {
const promises = snapshot.map(childSnapshot => {
return updateUnlocked(childSnapshot.val().isLocked, childSnapshot.val().locked, childSnapshot.key);
})
Promise.all(promises).then(() => {
console.log('done')
process.exit(0)
}).catch(err => {
console.log('error', err)
process.exit(1)
})
});
Demonstrating the control flow.
setTimeout(() => {
const x = [1, 2, 3]
const promises = x.map(i => {
return new Promise(resolve => resolve(i))
})
Promise.all(promises).then(() => {
console.log('done. process.exit(0) here')
})
}, 200)
If you want to exit on successful completion then refer below code:
Promise.all(promises).then(function(data) {
console.log(data);
process.exit(0);
}).catch(function(err) {
console.log('error');
});
If you want to exit on error as well then add process.exit(1) in catch block.
I am trying to retrieve attendance list along with user details.
I am using caminte.js(http://www.camintejs.com/) Cross-db ORM for database interaction.
Here is my code sample of model function "attendanceList".
exports.attendanceList = function (req, callback) {
var query = req.query;
var searchfilters = {};
if(!req.user){
callback({ code:400, status:'error', message: 'Invalid Request', data:{}});
}else{
searchfilters["vendor_id"] = parseInt(req.user._id);
}
if(query.location && parseString(query.location) != '') {
searchfilters["location"] = parseString(query.location);
}
if (query.device_details && parseString(query.device_details) != '') {
searchfilters["device_details"] = parseString(query.device_details);
}
if(query.created_on) {
searchfilters["created_on"] = query.created_on;
}
if(query.status) {
searchfilters["status"] = { regex: new RegExp(query.status.toLowerCase(), "i") };
}
var SkipRecord = 0;
var PageSize = 10;
var LimitRecord = PageSize;
var PageIndex = 1;
if(query.pagesize) {
PageSize = parseInt(query.pagesize);
}
if(query.pageindex) {
PageIndex = parseInt(query.pageindex);
}
if (PageIndex > 1) {
SkipRecord = (PageIndex - 1) * PageSize;
}
LimitRecord = PageSize;
var SortRecord = "created_on";
if(query.sortby && query.sorttype) {
var sortingBy = query.sortby;
var sortingType = 'ASC';
if(typeof query.sorttype !== 'undefined') {
sortingType = query.sorttype;
}
SortRecord = sortingBy + ' ' + sortingType;
}
Attendance.find({ where: searchfilters, order: SortRecord, limit: LimitRecord, skip: SkipRecord }, async function (err, result) {
if(err){
callback({ code:400, status:'error', message:'Unable to connect server', errors:err });
} else {
await result.map(function(row, i){
User.findById(parseInt(row.user_id), function(err, data){
if(err){
console.log(err);
} else {
result[i]['userDetails'] = data;
}
});
});
await Attendance.count({ where: searchfilters }, function (err, count) {
callback({ code:200, status:'success', message:'OK', total:count, data:result });
});
}
});
};
I am getting only attendance list without user details. How do I force to push user details into attendance list? Any Help!!
Thank You
This behavior is asynchronous. When you're making request to DB, your code keeps running, while task to get data comes to task queue.
To keep things simple, you need to use promises while handling asynchronous jobs.
Rewrite your code from this:
Attendance.find({ where: searchfilters, order: SortRecord, limit: LimitRecord, skip: SkipRecord }, async function (err, result) {
if(err){
callback({ code:400, status:'error', message:'Unable to connect server', errors:err });
} else {
await result.map(function(row, i){
User.findById(parseInt(row.user_id), function(err, data){
if(err){
console.log(err);
} else {
result[i]['userDetails'] = data;
}
});
});
await Attendance.count({ where: searchfilters }, function (err, count) {
callback({ code:200, status:'success', message:'OK', total:count, data:result });
});
}
});
To this:
const findAttendanceFirst = (searchFilters, SortRecord, LimitRecord, SkipRecord) => {
return new Promise((resolve, reject) => {
Attendance.find({ where: searchFilters, order: SortRecord, limit: LimitRecord, skip: SkipRecord }, (err, result) => {
if(err) return reject(err);
resolve(result);
});
});
}
const findUserByIdForUserDetails = (userId) => {
return new Promise((resolve, reject) => {
User.findById(parseInt(userId), function(err, data){
if(err) return reject(err);
resolve(data);
})
});
}
const getAttendanceCount = (searchFilters) => {
return new Promise((resolve, reject) => {
Attendance.count({ where: searchFilters }, (err, count) => {
if(err) return reject(err);
resolve(count);
});
})
}
So, now we can use this separate functions to make async behavior looks like sync.
try {
const data = await findAttendanceFirst(searchFilters, SortRecord, LimitRecord, SkipRecord);
for(let userData of data){
try {
userData.userDetails = await findUserByIdForUserDetails(userData.user_id);
} catch(e) {
// Some error happened, so no user details.
// you can set here null or nothing to userDetails.
}
}
let count;
try {
count = await getAttendanceCount(searchFilters);
} catch(e){
// Same as before.
}
const callBackData = { code:200, status:'success', message:'OK', total:count, data:result };
// And here you can do whatever you want with callback data. Send to client etc.
} catch(e) {
}
NB: I've not tested this code, it will be easier for yu to play with your actual data and use Promises and async/await
Just remember that each request to db is asynchronous, and you need to make your code wait for this data.