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value not setting in the variable which is defined outside in NodeJS

I'm new to NodeJS so please apologize if below code is not up-to the standard. I would like to access isSuccess value outside of this function stepfunctions.listExecutions
I tried below code but I'm getting the value is undefined not getting the expected output. I did some internet search and came to know in NodeJS we can't set the value which is defined in globally but I've use case and I'm pretty sure this is a common case for others too - where I would like to access this isSuccess value after my execution.
const AWS = require('aws-sdk');
const stepfunctions = new AWS.StepFunctions({
region: process.env.AWS_REGION
});
var params = {
stateMachineArn: 'arn:aws:states:us-west-1:121:stateMachine:test',
maxResults: '2',
nextToken: null,
statusFilter: 'SUCCEEDED'
};
var isSuccess
stepfunctions.listExecutions(params, function (err, data) {
if (err) console.log(err, err.stack);
else
data.executions.forEach(function (result) {
let params = {
executionArn: result.executionArn
};
stepfunctions.describeExecution(params, function (err, data) {
if (err) console.log(err, err.stack);
else {
isSuccess = 'true'
}
});
});
console.log('isSuccess: ' +isSuccess)
});
Expected output:
isSuccess: true
But I'm getting
isSuccess: undefined
Could you please help me to resolve this issue. Appreciated your help and support on this.

This is how you can wrap it on promise
let isSuccess;
const listExecute = function(params) {
return new Promise((resolve, reject) => {
stepfunctions.listExecutions(params, function (err, data) {
if (err) reject(err);
else
data.executions.forEach(function (result) {
let params = {
executionArn: result.executionArn
};
stepfunctions.describeExecution(params, function (err, data) {
if (err) reject(err);
else {
resolve(true)
}
});
});
});
})
}
async function getOutout(params) {
try {
isSuccess = await listExecute(params);
console.log(isSuccess, 'Output')
} catch(e) {
console.log(e)
}
}
getOutout(params)
Also you can export the listExecute so that you can use this function outside of this file.
module.exports = {listExecute}

How can integrate multiple functions into my post route and pass on objects

I want to integrate the Stripe api with my project. I am already collecting all needed data and sending it to my post route.
I want to make charges to a customer and have all functions to do so, if I would invoke them all one by one. How can I integrate all functions into my post route, so it is processed all at once. Also, I do not how to pass data from one function to another, so in the end there would be a function chain with the same data. My post route and functions:
router.post("/checkout", async function (req, res, next) {
if (!req.session.cart) {
return res.redirect("/shopping-cart");
}
// You can return promise directly
let createCustomer = function () {
var param ={};
param.email = req.body.email;
param.name= req.body.name;
param.description ="";
return stripe.customers.create(param, function (err, customer) {
if (err) {
console.log("err:" + err);
}
if (customer) {
console.log("success: " + JSON.stringify(customer, null, 2));
} else {
console.log("something went wrong");
}
});
};
let createToken = function () {
let param ={};
param.card = {
number: req.body.card,
exp_month: req.body.exp_month,
exp_year: req.body.exp_year,
cvc: req.body.security
}
return stripe.tokens.create(param, function (err, token) {
if (err) {
console.log("err:" + err);
console.log(param);
}
if (token) {
console.log("success: " + JSON.stringify(token, null, 2));
console.log(req.body);
} else {
console.log("something went wrong");
}
});
};
let addCardToCustomer = function () {
console.log(createdCustomer);
return stripe.customers.createSource(customer.id, {source: token.id}, function (err, card) {
if (err) {
console.log("err:" + err);
console.log(param);
}
if (card) {
console.log("success: " + JSON.stringify(card, null, 2));
} else {
console.log("something went wrong");
}
});
};
try {
const createdCustomer = await createCustomer(); // promise 1
const createdToken = await createToken();
const addedCardToCustomer = await addCardToCustomer(createdCustomer,createdToken ); // await addCardToCustomer(createdCustumer); to pass created customer info to next request
// const chargeCustomerThroughCustomerID = await chargeCustomerThroughCustomerID(); // promise 3
// more things...
res.send("success");
} catch (e) {
console.log(`error ${e}`)
};
});

you can chain your promises... / use async await and do one task at time in order you need. you can also pass data from one promise to another as shown below.
// You can return promise directly
let createCustomer = function () {
return stripe.customers.create(param);
}
let addCardToCustomer = function(){
return stripe.customers.createSource(customer.id,{source:token.id});
};
// or use async /await
let chargeCustomerThroughCustomerID = async function () {
const data = await stripe.charges.create(param).catch((e) => { console.log(`error ${e}`); throw e })
// do something with data
return data;
}
let chargeCustomerThroughTokenID = async function () {
const data = await stripe.charges.create(param).catch((e) => { console.log(`error ${e}`); throw e });
// do something with data
return data;
}
router.post("/checkout", async function(req, res, next) { // Async
if (!req.session.cart) {
return res.redirect("/shopping-cart");
}
var cart = new Cart(req.session.cart);
try {
const createdCustumer = await createCustomer(); // promise 1
const addCardToCustomer = await addCardToCustomer(); // await addCardToCustomer(createdCustumer); to pass created customer info to next request
const chargCustomer = await chargeCustomerThroughCustomerID(); // promise 3
// more things...
res.send(...);
}
catch(e) {
console.log(`error ${e}`)
}
});

How to store the RFC822 message body body as String?

var inbox = require("inbox");
var client = inbox.createConnection(false, "imap.gmail.com", {
secureConnection: true,
auth:{
user: "myemail#gmail.com",
pass: "mypass"
}
});
client.connect();
client.on("connect", function(){
client.openMailbox("INBOX", function(error, info){
if(error) throw error;
client.listMessages(-10, function(err, messages){
var datas = [];
var data;
messages.forEach(function(message){
data = message.UID + ": " + message.title;
datas.push(data);
});
var messageStream = client.createMessageStream(22048);
console.log(messageStream);
client.close();
});
});
});
The above code returns
Stream {
domain: null,
_events: {},
_eventsCount: 0,
_maxListeners: undefined }
But by replacing
var messageStream = client.createMessageStream(22048);
console.log(messageStream);
with
client.createMessageStream(123).pipe(process.stdout, {end: false});
I get the entire RFC822 message body in terminal
How to store the RFC822 message body body as String?
I tried my best to do it but everytime it returns the same
how can i do it?

Since its a readable stream you can use NodeJS - Class: stream.Readable
You can use data event to get the message from stream and end event to know when there is no more data
Event: 'data'
const readable = getReadableStreamSomehow();
readable.on('data', (chunk) => {
console.log(`Received ${chunk.length} bytes of data.`);
});
Event: 'end'
const readable = getReadableStreamSomehow();
readable.on('data', (chunk) => {
console.log(`Received ${chunk.length} bytes of data.`);
});
readable.on('end', () => {
console.log('There will be no more data.');
});
P.S. createMessageStream accepts as argument a message UID.
In your case you might have to wrap this up with some promise base functions
Example
var inbox = require("inbox");
var client = inbox.createConnection(false, "imap.gmail.com", {
secureConnection: true,
auth: {
user: "myemail#gmail.com",
pass: "mypass"
}
});
client.connect();
client.on("connect", function() {
client.openMailbox("INBOX", function(error, info) {
if (error) throw error;
var emails = [];
var promises = [];
new Promise(function(resolve, reject) {
client.listMessages(-10, function(err, messages) {
if (err) {
reject(err)
return;
};
messages.forEach(function(message) {
var promise = new Promise(function(resolve, reject) {
var email = {
UID: messages.UID,
title: message.title,
body: ""
}
client.createMessageStream(message.UID)
.on('data', (chunk) => {
email.body += chunk.toString();
}).on('end', () => {
//return the email object
resolve(email);
}).on('error', (err) => {
reject(err);
});
})
promises.push(promise);
});
resolve();
});
}).then(() => {
return Promise.all(promises).then(function(emails) {
console.log(emails);
console.log("closing");
client.close();
})
})
});
});

use of then / catch in $http call in angular

I my Node backend have the following end-point:
usersRoute.get('/get', function(req, res) {
//If no date was passed in - just use todays date
var date = req.query.date || dateFormat(new Date(), 'yyyy-mm-dd'),
search = req.query.search;
users.getAllUsers(date, search)
.then(function(results) {
res.json(results);
}, function(err) {
res.status(500).json({
success: false,
message: 'Server error.',
data: []
});
});
});
I have changed my sql table name to something else to trigger the function(err){} part
When I use this in my service it looks like this:
function getUsers(date, search) {
return $http.get('/api/users/get', {
params: {
date: UtilsService.formatDate(date),
search: search
}
})
.then(getData)
.catch(handleErr);
function getData(response) {
return response.data;
}
function handleErr(err) {
LoggerService.error('Could not retrieve users.', err ,'Ooops');
}
}
Knowing the server will return an http status code 500, I thought it would go right to the catch block. But it also returns the data /which is undefined in the then block
I use my service in my controller like this:
function getUsers(date, search) {
isAdmin();
vm.loading = true;
vm.filteredUsers = [];
return UsersService.getUsers(date, search).then(function(data) {
vm.loading = false;
allUsers = data || [];
vm.filteredUsers = allUsers.slice(0, 50);
vm.distribution = UsersService.getDistribution(allUsers);
return vm.filteredUsers;
});
}
My problem is, since the then part is triggered in my service. I'm trying to slice undefined
My question is: What are som best practices when it comes to this sort of pattern.

The problem is that your catching the error from your API and then returning the promise created by .catch.
Quick example
promise.then(function(data) {
throw 'Some error';
}).catch(function (err) {
console.log(err) // will output 'Some error'
}).then(function () {
// This will run even though we have a catch before
});
So how can we prevent the .then it's easy we throw an error inside the .catch
promise.then(function(data) {
throw 'Some error';
}).catch(function (err) {
console.log(err) // will output 'Some error'
throw 'You shall not pass'
}).then(function () {
// This will not run
});
So in your case you have two options, one throw an error as I said or two inject the $q service into your service:
function getUsers(date, search) {
return $http.get('/api/users/get', {
params: {
date: UtilsService.formatDate(date),
search: search
}
})
.then(getData)
.catch(handleErr);
function getData(response) {
return response.data;
}
function handleErr(err) {
LoggerService.error('Could not retrieve users.', err ,'Ooops');
return $q.reject(err);
}
}

You could do something like that
function getUsers(date, search, cb) {
return $http.get('/api/users/get', {
params: {
date: UtilsService.formatDate(date),
search: search
}
})
.then(cb)
.catch(handleErr);
function handleErr(err) {
LoggerService.error('Could not retrieve users.', err ,'Ooops');
}
}
And then in your controller
UsersService.getUsers(date, search, function(data) {
vm.loading = false;
allUsers = data || [];
vm.filteredUsers = allUsers.slice(0, 50);
vm.distribution = UsersService.getDistribution(allUsers);
});

How promise works with nested function calls

I have a piece of code which deals with user's data. There are bunch of nested function calls :
f1(){
f2(){
....
fn{
///
}
}
}
fn accesses a database which means it's asynchronous, so I wrote it somehow that it returns a promise and in fn-1 (the function which calls fn) , we use .then() to wait for this promise. But it looks like now I have to return a promise in fn-1 and so on. Is that true ?
var keyValueExists = function(key, value) {
var query = {};
query[key] = value;
return new Promise(function(resolve, reject) {
User.count(query, function(err, count) {
if (err) {
console.log(err);
console.log('Problem with `.find` function');
reject('Problem with `.find` function');
} else {
resolve(count !== 0);
}
});
});
};
var addUser = function(newUserInfo) {
var validationResult = Common._validateUserInfo(newUserInfo);
if (validationResult.isOK) {
keyValueExists('userName', newUserInfo.userName).then(function(userNameAlreadyExists) {
if (userNameAlreadyExists) {
validationResult = {
isOK: false,
reason: 'Username already exists',
infoWithBadInput: 'userName'
}
} else {
var newUserId = generateUserId();
//TODO: change it somehting more flexible. e.g. a predefined list of attributes to iterate over
var newUser = {
'userName': newUserInfo.userName,
'password': newUserInfo.password,
'userId': newUserId,
'lastModificationTime': Common.getCurrentFormanttedTime(),
'createdTime': Common.getCurrentFormanttedTime()
};
var user = new User(newUser);
user.save(function(err) {
if (err) {
console.log(err);
console.log('There is a problem saving the user info');
} else {
console.log('A new user added: ');
console.log(newUser);
}
});
}
return validationResult;
});
} else {
return validationResult;
}
};
addUser returns undefined ! It looks like that the caller of addUser doesn't wait for it !

This is what you are effectively doing in your addUser function
var addUser = function(newUserInfo) {
var validationResult = Common._validateUserInfo(newUserInfo);
if (validationResult.isOK) {
// ... do something asynchronously without returning anything
} else {
return validationResult;
}
}
So, yeah, if validationResult.isOK, adduser WILL return undefined
Here's some code loosely based on your code, but it runs standalone to demonstrate how you possibly should be doing things
var keyValueExists = function(key, value) {
// pseudo junk, this simulates any username starting with b as existing
return new Promise(function(resolve, reject) {
resolve(value.substr(0,1) == 'b'); // barny and betty are dupes, fred and wilma are not
});
}
var addUser = function (newUserInfo) {
// var validationResult = Common._validateUserInfo(newUserInfo);
var validationResult = {isOK: !!~(['fred', 'barny'].indexOf(newUserInfo.userName)), username: newUserInfo.userName}; // dummy code
if (validationResult.isOK) {
return keyValueExists('userName', newUserInfo.userName).then(function (userNameAlreadyExists) {
if (userNameAlreadyExists) {
validationResult = {
isOK: false,
reason: 'Username already exists',
infoWithBadInput: 'userName',
username: newUserInfo.userName
}
} else {
// create new user here
validationResult.userNumber = (Math.random() * 100000000) | 0;
}
return validationResult;
});
}
else {
// this function always needs to return a promise, even if it is resolved/rejected immediately
return Promise.reject(validationResult);
}
}
addUser({userName: 'fred'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});
addUser({userName: 'wilma'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});
addUser({userName: 'barny'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});
addUser({userName: 'betty'}).then(function (result) {
console.log(result);
}).catch(function(err) {
console.error(err);
});