Bluebird promises - each function - node.js

Question

Thank in advance for the help.
While using Bluebird promises, I have a series of promises running. During the last promise, I want to run one function multiple times for each object in an array.
Below there is the pseudocode:
var userArray = [
{
name: "John",
email: "John#email.com"
},
{
name: "Jane",
email: "jane#email.com"
}];
var functionOne = function() {
//returns Promsie object
};
var functionTwo = function() {
//returns promise object
};
var createUser = function(user) {
return User.findOrCreate({email: user.email},{
name: user.name,
email: user.email
});
};
functionOne()
.then(functionTwo)
.each(createUser(userArray))
.then(function onComplete() {
console.log("Complete");
})
.catch(function onError() {
console.log("Um...it's not working");
});
I know I'm not using the each function correctly. What's the correct way to implement this using Bluebird?

Answer 1

As I understand you want to take some asynchronous actions for elements from array. Then please check the following example:
var Promise = require('bluebird');
function createUsersFromArray(userArray){
return Promise.each(userArray, function(signleUser){
return createUserFunction(signleUser);
});
}
or
return Promise.each(userArray, createUserFunction);
functionOne()
.then(functionTwo)
.then(function(){
return createUsersFromArray(userArray);
})
//or just .then(createUsersFromArray) if functionTwo return this array
.then(function(createdUsers){
//here you may retrieve users and make some magic with them
console.log(createdUsers);
})
.then(function onComplete() {
console.log("Complete");
})
.catch(function onError() {
console.log("Um...it's not working");
});
I also recommend using "all" instead of "each"
Check the examples below:
return Promise.all(userArray.map(function(singleUser){
return doSomethingWithUser(singleUser);
}));
or
return Promise.all(userArray.map(doSomethingWithUser));
'all' will notify you if all the actions are taken correctly.
How to use promises (best practice):
http://pouchdb.com/2015/05/18/we-have-a-problem-with-promises.html
https://blog.domenic.me/youre-missing-the-point-of-promises/

Answer 2

The most straightforward implementation:
functionOne()
.then(functionTwo)
.then(function(){
return bluebird.each(userArray, createUser);
})
.then(function onComplete() {
console.log("Complete");
})
.catch(function onError() {
console.log("Um...it's not working");
});
You should use .map instead of .each if you want to access the results of all of those creates.

Answer 3

Thanks #Roman #Yuri for the help! My now working code is below:
var userArray = [
{
name: "John",
email: "John#email.com"
},
{
name: "Jane",
email: "jane#email.com"
}];
var functionOne = function() {
//returns Promise object
};
var functionTwo = function() {
//returns Promise object
};
var createUser = function(singleUser) {
//returns Promise object containing creating User
};
functionOne()
.then(functionTwo)
.then(function() {
return Promise.map(userArray, createUser);
})
.then(function onComplete(response) {
console.log("Complete:" + JSON.stringify(response));
})
.catch(function onError() {
console.log("Um...it's not working");
});