I have a list of company and would like to calculate a total amount of invoices issued to each company. The following is the code that I wrote. (Actual logic is more complicated within the loop but took them out here)
Basically I want to alert the message once the business logic within the loop is complete (Again, it will do something more complex here). I got a feeling that I can resolve this issue by using Promises but am not quite sure how to use it. I didn't quite follow Parse.com's document. I have been stuck with this for a few hours. Please help!
function calculate(companies) {
companies.forEach(function(company) {
var total = 0;
var invoice = Parse.Object.extend('Invoice');
var query = new Parse.Query(invoice);
query.equalTo('invoiceCompany', company);
query.find().then(function(invoices) {
invoices.forEach(function(invoice) {
total += parseFloat(invoice.get('amount'));
});
});
});
alert("Calculated Finished");
}
You can use promises in paralell:
https://parse.com/docs/js/guide#promises-promises-in-parallel
It would be something like this:
function calculate(companies) {
var promises = [];
companies.forEach(function(company) {
var total = 0;
var invoice = Parse.Object.extend('Invoice');
var query = new Parse.Query(invoice);
query.equalTo('invoiceCompany', company);
var queryPromise = query.find().then(function(invoices) {
invoices.forEach(function(invoice) {
total += parseFloat(invoice.get('amount'));
});
});
promises.push(queryPromise);
});
return Parse.Promise.when(promises);
}
calculate(companies).then(function() {
alert("Calculated Finished");
});
Related
router.post("/cart/paycash/add-order",(req,res) => {
req.checkBody("emri","Ju lutem vendosni emrin").notEmpty();
req.checkBody("mbiemri","Ju lutem vendosni mbiemrin").notEmpty();
req.checkBody("numritelefonit","Ju lutem vendosni numrin e telefonit").notEmpty();
req.checkBody("qyteti","Ju lutem vendosni qytetin").notEmpty();
var emri = req.body.emri;
var mbiemri = req.body.mbiemri;
var telefoni = req.body.numritelefonit;
var email = req.body.email;
var qyteti = req.body.qyteti;
var adresa = req.body.adresa;
var Cart = req.session.cart;
var errors = req.validationErrors();
if(errors) {
res.redirect("/cart/checkout", {
errors:errors
});
}
else {
Orders.find({}, function(err,orders) {
if(err) {
console.log(err);
}
else {
var order=new Orders({
emri:emri,
mbiemri:mbiemri,
telefoni:telefoni,
email:email,
qyteti:qyteti,
adresa:adresa,
});
console.log(Cart.length);
Cart.forEach(function(product) {
var cart = Cart.length;
var productTitle = product.title;
console.log(productTitle);
for (var i = 0; i < 1; i++) {
Products.findOne({title:product.title}, function(err,foundproduct) {
console.log(foundproduct.title)
order.products.push(foundproduct);
order.save();;
});
}
});
}
});
delete req.session.cart;
delete req.session.promocode;
res.redirect("/dyqani");
}
});
I want to make this code works, but for this I need async. I have tried some methods but I couldn't made it work. Can anyone help me? I want to be able to add in my order database all the products that are in the cart, but because mongoose is async and JavaScript is not, some of the queries get loaded before and the results in my database are not the ones that are in my cart.
It seems like you're trying to asynchronously request for every product that's in your cart. You don't need the nested for loop in your forEach function, because that loop doesn't seem to do anything.
You need to first map all the async requests in an array and run Promise.all to request them all asynchronously
let products = Cart.map((product) => {
return Products.findOne({title:product.title},(err,foundproduct) => {
//your save product to order logic
});
})
Promise.all(products).then((complete) => {
console.log('product added')
})
Here's a detailed explanation on how promises work in javascript Javascript Promises
Your application design pattern is also uncommon, but that's outside the scope of this question.
I am new to Knockout and I have a little problem stopping me from completing my simple project.I have an observableArray called loanDeductions that I display in a table with foreach binding. I have another observableArray called loanDeductionsList which is also from the json data of my first observableArray, I used it in my drop down list which when a value is selected, it will push the selected data to my table. If it didn't make sense as I cannot really explain it clearly, this is my javascript file:
var deductionLine = function (deductionID, deductionName, amount) {
self = this;
self.deductionID = ko.observable(deductionID);
self.deductionName = ko.observable(deductionName);
self.amount = ko.observable(formatCurrency(amount));
};
function LoanDeductions(deductions) {
var self = this;
self.loanDeductions = ko.observableArray(ko.utils.arrayMap(deductions, function (deduction) {
return new deductionLine(deduction.deductionID, deduction.deductionName, deduction.amount)
}));
self.loanDeductionsList = ko.observableArray(ko.utils.arrayMap(deductions, function (deduction) {
return new deductionLine(deduction.deductionID, deduction.deductionName, deduction.amount)
}));
self.selectedDeduction = ko.observable();
self.selectedDeduction.subscribe(function (data) {
self.loanDeductions.push({
deductionID: data.deductionID,
deductionName: data.deductionName,
amount: data.amount,
});
});
}
Can you help me find a way to make my function selectedDeduction.subscribe() push the data ONLY when the item to be pushed is not existing in my loanDeductions observableArray.
Any help will be greatly appreciated. Thank you!
I am somewhat aware that the way I populate my dropdown list may o may not be the best way to do it, I am open to suggestion of a better way and rewrite my program.
just to share what I did I added this line in my selectedDeduction.subscribe():
self.selectedDeduction.subscribe(function (data) {
var match = ko.utils.arrayFirst(self.loanDeductions(), function(deduction) {
return deduction.deductionID() === data.deductionID();
});
if (match) {
alert(data.deductionName() + ' already exists!');
} else {
self.loanDeductions.push({
deductionID: data.deductionID,
deductionName: data.deductionName,
amount: data.amount,
});
}
});
New to javascript here, so callbacks are still a little iffy in my brain.
What I'm trying to do is: given a "menu" which is an array of objectId's, query for each foodItem that corresponds to that objectId, get its votes, put it in a min-heap (to determine which are the top 5 items), and return those top 5 items.
My heap at the end is empty because I realize that JavaScript is asynchronous and that when I try to get the heap data, the callback might not have necessarily completed.
If it were just one call, I would just nest the callbacks, but since this is a loop I'm not really sure what to do.
function getTopFoods(menu, heap, callback) {
//go through each objectId, get its foodItem and then its votes, then heap it
console.log("got to TopFoods");
for (var i = 0; i < menu.length; i++) {
var foodID = menu[i];
var FoodItem = Parse.Object.extend("FoodItem");
var foodQuery = new Parse.Query(FoodItem);
foodQuery.equalTo("objectId", foodID);
//get corresponding foodItem
foodQuery.find({
success: function(foodResult) {
//got specific food Item
var votes = foodResult.get("votes");
console.log("votes: " + votes);
if (heap.length < 5) {
heap.queue(foodResult);
} else {
if (votes > heap.peek().get("votes")) {
heap.dequeue();
heap.queue(foodResult);
}
}
},
error: function(error) {
console.log("Food error: " + error.code + " " + error.message);
}
});
}
var topFoods = [];
for (var i = 0; i < 5; i++) {
topFoods[i] = heap.dequeue();
}
callback(topFoods);
}
The easiest way is to use promises; at this stage, this involves using a library (coming to JavaScript proper in ES6). If you want a low-tech solution, just count stuff:
var waitingCount = menu.length;
for (....) {
...
success: function(foodResult) {
...
if (!--waitingCount) {
callback(topFive(heap));
}
},
error: function(error) {
--waitingCount;
...
}
...
}
This is just the basic idea. It would be good if you also decremented the counter on failed responses, since this way a single fail will leave you hanging.
EDIT: Err, obviously, the check needs to go to the bottom of success, not to the top as my snippet indicated before, or you'll miss the last element. I also put in the error case.
EDIT2: As eth3lbert notes, parse.com API also supports promises (I don't work with parse.com, so... thanks for the tip). In that case, here's what you do:
var promises = [];
for (....) {
var promise = foodQuery.find({
...
});
promises.push(promise);
});
Parse.Promise.when(promises).then(function()) {
callback(topFive(heap));
}
I have a search suggestion script that pulls results from two Google APIs, orders the results by an integer value and then displays it to a user. The script ensures it only returns the five most relevant responses for each query based on the rel attribute of each.
JSFiddle: http://jsfiddle.net/22LN5/
However, with this current set-up there is no fault tolerance; for example one API being on available or exceeding the query limit on one API so no results are returned.
How can this be resolved?
My jQuery code is:
var combined=[];
$(document).ready(function(){
$("#search").keyup(function(e){
$(this).html("");
$.getJSON("http://suggestqueries.google.com/complete/search?q="+$("#search").val()+"&client=chrome&callback=?",function(data1){
$.getJSON("https://www.googleapis.com/freebase/v1/search?query="+$("#search").val()+"&limit=3&encode=html&callback=?",function(data2){
for(var key in data1[1]){
if(data1[4]["google:suggesttype"][key]=="NAVIGATION"){
combined.push("<li rel='"+data1[4]["google:suggestrelevance"][key]+"'><a href='"+data1[1][key]+"'>"+data1[2][key]+"</a></li>");
}else{
combined.push("<li rel='"+data1[4]["google:suggestrelevance"][key]+"'>"+data1[1][key]+"</li>");
}
}
for(var key in data2.result){
combined.push("<li rel='"+Math.round(data2.result[key].score*5)+"'> Freebase: "+data2.result[key].name+"</li>");
}
combined.sort(function(a,b){
return +$(b).attr("rel")-+$(a).attr("rel");
});
$("#suggest").html(combined.slice(0,5).join(""));
combined=[];
});
});
});
});
I've updated your fiddle: http://jsfiddle.net/22LN5/2/
I whipped up $.whenFaultTolerant, which will always return the promise in the event of completion or failure. Pass in a hash of deferreds, and out comes a hash of results! This is not a complete solution but I hope it is a good step in the right direction.
$.whenFaultTolerant = function(things) {
var remaining = Object.keys(things).length;
var outputs = {};
var dfd = $.Deferred();
$.each(things, function(key, thing) {
thing.always(function(data) {
outputs[key] = data;
--remaining || dfd.resolve(outputs);
});
});
return dfd.promise();
};
Usage:
$.whenFaultTolerant({
suggestqueries: $.getJSON("http://suggestqueries.google.com/complete/search?q="+$("#search").val()+"&client=chrome&callback=?"),
googleapis: $.getJSON("https://www.googleapis.com/freebase/v1/search?query="+$("#search").val()+"&limit=3&encode=html&callback=?")
}).done(function(data){
console.log(data);
});
Outputs:
{
"suggestqueries": <the results from suggestqueries.google.com>,
"googleapis": <the results from www.googleapis.com>
}
In an simple web app that i am building using underscore.js and jquery. For a list of all people ( js object ) I am filtering out list of all the places (js object) they visited. People list is a html table with a td having places image icon which on click displays list of all places they visited. Icon needs to be shown only for people who have visited at the least one place. The problem here is that people and places count comes around 2000, 100. So the code below executes 2000*100 combinations. The browser complains me of unresponsive script. Code is provided below
_.each(peopleList, function (person, index, list) {
//filter the respective places for people
var visitedPlaces = _.filter(places, function (place) {
return place.PeopleId == person.Id;
});
if (_.isEmpty(visitedPlaces)) {
$("a#" + place.PeopleId).remove();
}
});
Dead simple isn't it. For each person check if visited places has him tracked. How do i optimize the above code to unblocking and responsive. Tried putting in _.defer and _.delay at some places but no improvement
FWIW, here is how I would solve it in underscore.
function removeNonTravelers(people, visits) {
var travelers = _.pluck(visits, 'PeopleId'),
nonTravelers = _.reject(people, function (person) {
return _.contains(travelers, person.Id);
});
$(_.map(nonTravelers, document.getElementById)).remove();
}
http://jsfiddle.net/FWzeN/
My suggestion would be to drop underscore and use plain JS for this:
function removeNonTravelers(people, visits) {
var i, peopleId,
numPeople = people.length,
numVisits = visits.length,
index = {}, nonTravelers = [];
// index
for (i = 0; i < numVisits; i++) {
peopleId = visits[i].PeopleId;
if (!index.hasOwnProperty(peopleId)) {
index[peopleId] = 1;
} else {
index[peopleId]++;
}
}
// find HTML elements to remove
for (i = 0; i < numPeople; i++) {
peopleId = people[i].Id;
if (!index.hasOwnProperty(peopleId)) {
nonTravelers.push(document.getElementById(peopleId));
}
}
// remove them all at once
$(nonTravelers).remove();
}
This is reasonably fast. If I didn't make any mistake, your test case (2000 people, 100 places) times at more than 700 operations per second on my rather outdated laptop (DOM operations excluded).
Try for yourself: http://jsperf.com/where-not-exists-in-javascript
var hashMap = {};
_.each(places, function(place) {
hashMap[place.PeopleId] = place;
});
_.each(peopleList, function (person, index, list) {
//filter the respective project documents
var visitedPlaces = hashMap[person.id];
if (visitedPlaces) {
$("a#" + place.PeopleId).remove();
}
});