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JavaScript promises with nested AJAX calls are not working

On my code I hava a function with 3 nested AJAX calls, in order for it to work I had to set Async=false.
As I have read that Async=false is deprecated I replaced the Async=false with promises.
This is my function before I edited it:
self.getOrders = function (name) {
var orders= [];
var order= function (item, type1, type2) {
var self = this;
self.order= item;
self.type1= type1;
self.type2= type2;
}
$.ajax({
url: "/API/orders/" + name,
type: "GET",
async: false,
success: function (orderResults) {
var mappedOrders = $.map(orderResults, function (orderItem) {
$.ajax({
url: "/API/orders/property/" + orderItem.id + "/type1",
type: "GET",
async: false,
success: function (property1Results) {
$.ajax({
url: "/API/orders/property/" + orderItem.id + "/type2",
type: "GET",
async: false,
success: function (property2Results) {
orders.push(new order(orderItem, property1Results, property2Results));
}
});
}
});
})
}
});
return orders;
This function worked perfectly, I got the data end everything worked fine.
Then I changed the function to use promises instead of Async=false,
this is the edited function, with promises:
//The begin of the function- same as first one
var orders= [];
var firstPromise = $.ajax({
url: "/API/orders/" + name,
type: "GET"
});
$.when(firstPromise).done(function (orderResults) {
var mappedOrders = $.map(orderResults, function (orderItem) {
var secondPromise = $.ajax({
url: "/API/orders/property/" + orderItem.id + "/type1",
type: "GET"
});
$.when(secondPromise).done(function (property1Results) {
var thirdPromise = $.ajax({
url: "/API/orders/property/" + orderItem.id + "/type2",
type: "GET"
});
$.when(thirdPromise).done(function (property2Results) {
orders.push(new order(orderItem, property1Results, property2Results));
});
});
});
});
return orders;
And the function call:
self.populateOrders = function (name) {
var mappedOrders = $.map(self.service.getOrders(name), function (item) {
return new Order(item)
});
self.orders(mappedOrders);
}
The new function is not working, I'm getting back from the firstPromise a wrong json with backslashes, and the returned orders object is empty.
Any idea what am I doing wrong? I spent so much time on it but couldn't figure it out.
Thanks in advance.

Nested ajax calls inside a loop is a hell to manage. You can do it like this.
Create a promise to notify the caller when the whole process is finished
Wait for all the inner ajax calls to resolve
Resolve you main promise to notify the caller
self.getOrders = function (name) {
var mainDeferred = $.Deferred();
var orders = [];
var order = function (item, type1, type2) {
var self = this;
self.order = item;
self.type1 = type1;
self.type2 = type2;
}
$.ajax({
url: "/API/orders/" + name,
type: "GET",
success: function (orderResults) {
var innerwait = [];
var mappedOrders = $.map(orderResults, function (orderItem) {
var ajax1 = $.ajax({
url: "/API/orders/property/" + orderItem.id + "/type1",
type: "GET"
});
var ajax2 = $.ajax({
url: "/API/orders/property/" + orderItem.id + "/type2",
type: "GET"
});
$.when(ajax1, ajax2).done(function (property1Results, property2Results) {
orders.push(new order(orderItem, property1Results[0], property2Results[0])))
});
innerwait.push(ajax1, ajax2);
});;
$.when.apply(null, innerwait) //make sure to wait for all ajax requests to finish
.done(function () {
mainDeferred.resolve(orders); //now that we are sure the orders array is filled, we can resolve mainDeferred with orders array
});
}
});
return mainDeferred.promise();
}
self.populateOrders = function (name) {
self.service.getOrders(name).done(function (orders) { //use .done() method to wait for the .getOrders() to resolve
var mappedOrders = $.map(orders, function (item) {
return new Order(item)
});
self.orders(mappedOrders);
});
}
In the example, note that I use $.when.apply() to wait for an array of deferreds.

A bug recently introduced in chrome 52 (august 2016) can cause this kind of behavior : answers for nested requested are ignored.
Hoppefully, it will not last long.
https://bugs.chromium.org/p/chromium/issues/detail?id=633696
Try to add cache: false

Javascript response and ajax request

I have the following:
function wikiAjax (searchURL) {
return Promise.resolve($.ajax({
url: searchURL,
jsonp: "callback",
dataType: 'jsonp',
xhrFields: {
withCredentials: true
},
}));
}
$(".search-form").submit(function() {
var searchText = $('#search').val();
var searchURL = "https://en.wikipedia.org/w/api.php?format=json&action=query&generator=search&gsrsearch=" + searchText + "&gsrlimit=15&prop=extracts&exsentences=3&exintro=&explaintext&exlimit=max&callback=JSON_CALLBACK";
console.log(searchURL);
var wikiResponse = wikiAjax(searchURL);
wikiResponse.then(function(data) {
alert(data);
}, function() {
alert("The call has been rejected");
});
});
But i get an answer only if I put a breakpoint somewhere (e.g. at the wikiResponse.then line).
Then it looks like the code is executed before the call returns the result but why? Isn't the promise set properly?
Many thanks in advance.

I think what might be happening here is the browser is executing the default submit event on the form in addition to the ajax call. The result is that the window is unloaded and reloaded.
Try putting:
event.preventDefault();
in the handler.
$(".search-form").submit(function(event) {
event.preventDefault();
var searchText = $('#search').val();
var searchURL = "https://en.wikipedia.org/w/api.php?format=json&action=query&generator=search&gsrsearch=" + searchText + "&gsrlimit=15&prop=extracts&exsentences=3&exintro=&explaintext&exlimit=max&callback=JSON_CALLBACK";
console.log(searchURL);
var wikiResponse = wikiAjax(searchURL);
wikiResponse.then(function(data) {
alert(data);
},
function() {
alert("The call has been rejected");
}
);
});

I think Promise.resolve() is an ES6 feature so unless you explicitly make sure you support it it should not work.
But, lucky for you $.ajax() return a promise in the following format:
var promise = $.ajax({
url: "/myServerScript"
});
promise.done(mySuccessFunction);
promise.fail(myErrorFunction);
(and not with then() and catch() like was written in your code)

It's unnecessary to do Promise.resolve here, because the $.ajax call already returns a promise.
Try this:
function wikiAjax (searchURL) {
return $.ajax({
url: searchURL,
jsonp: "callback",
dataType: 'jsonp',
xhrFields: {
withCredentials: true
}
});
}
$(".search-form").submit(function() {
var searchText = $('#search').val();
var searchURL = "https://en.wikipedia.org/w/api.php?format=json&action=query&generator=search&gsrsearch=" + searchText + "&gsrlimit=15&prop=extracts&exsentences=3&exintro=&explaintext&exlimit=max&callback=JSON_CALLBACK";
console.log(searchURL);
var wikiResponse = wikiAjax(searchURL);
wikiResponse.done(function(data) {
alert(data);
}).fail(function(err) {
alert("The call has been rejected");
});
});
This is a working (and modified to show) plunker: https://plnkr.co/edit/qyc4Tu1waQO6EspomMYL?p=preview

Sending a variable with ajax call .done

Is there a possible way to send the variable, 'schedule_id[i]', with the result of the call. Also is it possible to add this variable in the data object?
My code:
for (var i = 0; i < schedule_id.length; i++) {
//Ajax call
$.ajax({
url: "http://api.viewer.zmags.com/schedules/" + schedule_id[i] + "?key=" + api_key
})
//
.done(function(data){
}

So you need asynchronies ajax call in synchronies manner right?
So you need to create one separate function which is call ajax request and return the result and use in subsequent request.
Like:-
for (var i = 0; i < schedule_id.length; i++) {
var result;
if (i == 0)
result = callfunction(0,schedule_id[i]);
else
result = callfunction(result,schedule_id[i]);
}
function callfunction(passresult,schedule_id) {
$.ajax({
url: "http://api.viewer.zmags.com/schedules/" + schedule_id + "?key=" + api_key
})
.done(function (data) {
return data;
});
}

construct the ajax call like this:
$.ajax({
url: 'http://api.viewer.zmags.com/schedules/',
type: 'POST' // or GET,
data: {
schedule_ids: schedule_id, //array
key: api_key
},
success: function (data) {
//success callback
}
});

jQuery Ajax Race Condition best practice

In a button.click(function(){}); I have the following code:
var userId = $("#user-permission-edit").val();
var peId = $("#user-permission-entity-list").val();
var newParentPEId = $("#new-parent-pe").val();
var newPeName = $("#pe-name-add").val();
$.ajax({
type: "POST",
url: 'AddNewPE',
data: { 'targetUserId': userId, 'targetPEId': peId, 'newPeParentId': newParentPEId, 'newPeName': newPeName},
success: function (data) {
var dataObj = jQuery.parseJSON(data);
console.log(dataObj);
if (dataObj.status == "success") {
alert("Permissions have been updated.");
}
//update user PEs combo
}
});
However, I am concerned of a possible race condition of the variables not getting the values in time for the ajax call.
would something like this be safer?
var userId = $("#user-permission-edit").val();
var peId = $("#user-permission-entity-list").val();
var newParentPEId = $("#new-parent-pe").val();
var newPeName = $("#pe-name-add").val();
$.when(function() {
userId = $("#user-permission-edit").val();
peId = $("#user-permission-entity-list").val();
newParentPEId = $("#new-parent-pe").val();
newPeName = $("#pe-name-add").val();
}).done(function() {
$.ajax({
type: "POST",
url: 'AddNewPE',
data: { 'targetUserId': userId, 'targetPEId': peId, 'newPeParentId': newParentPEId, 'newPeName': newPeName},
success: function (data) {
var dataObj = jQuery.parseJSON(data);
console.log(dataObj);
if (dataObj.status == "success") {
alert("Permissions have been updated.");
}
//update user PEs combo
}
});
});
Is this even necessary?

The $('....').val() method is a synchronous call - your script execution won't continue past that line until you have received the value of that element.

JQuery won't pass data labeled sessid when calling drupal service module

Hey all I am working on a json call that will implement Drupal's services module with json. I am using jquery's ajax function to call the function but I am getting an error stating that no parameters are being passed. When I look at the query string being posted I notice that sessid is not being passed even though its with the parameters. Below is what Im running.
// JavaScript Document
$(document).ready(function() {
function drupalConnect(src) {
$.ajax({
url: src,
type: 'POST',
data: {
method: 'system.connect'
},
success: function(data) {
return data["result"]["sessid"];
}
});
}
function getTimestamp() {
return Math.round((new Date).getTime() / 1000);
}
function randString(length) {
var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
var randomstring = '';
for (var i = 0; i < length; i++) {
var rnum = Math.floor(Math.random() * chars.length);
randomstring += chars.substring(rnum, rnum + 1);
}
return randomstring;
}
var session_id = drupalConnect('http://localhost/drupal/services/json-rpc');
var nonce = randString(10);
var timestamp = getTimestamp();
var username = "markusgray";
var password = "Markus1990";
var key = '2ae0392e0aebbfeeddefcc962ea1924f';
var domain = 'localhost';
var hashObj = new jsSHA(timestamp + ";" + domain + ";" + nonce + ";user.login", "TEXT");
var hash = hashObj.getHMAC(key, "TEXT", "SHA-256", "HEX");
var parameters = {
hash: hash,
domain_name: domain,
domain_time_stamp: timestamp,
nonce: nonce,
sessid: session_id,
username: username,
password: password
};
var par = JSON.stringify(parameters);
$.ajax({
url: 'http://localhost/drupal/services/json-rpc',
type: 'POST',
dataType: 'json',
data: {
method: 'user.login',
params: par
},
success: function() {
}
});
});​

drupalConnect doesn't return anything, also the return from the success callback is just thrown away. The best way to use the data returned from an ajax call is to use it in thee callback itself.
function drupalConnect(src){
$.ajax({
url: src,
type: 'POST',
data:{method:'system.connect'},
success: function(data){
var session_id = data["result"]["sessid"];
//use session_id here
}
});
}

It is because of the Asynchronous ajax, let me elaborate, to get the session_id you are making an ajax call. At the moment it will send the request, but it wont ensure that the session_id will be assigned at that moment. Hence when you making the second ajax call, the session_id may not be assigned for a value.
There are two workarounds for this,
One is, making the first ajax call with an option async:false and assign the value within the success call, something like
var session_id;
function drupalConnect(src) {
$.ajax({
url: src,
type: 'post',
async : false,
data: {
method: 'system.connect'
},
success: function(data) {
session_id = data["result"]["sessid"];
}
});
};
DEMO
The second one and preferred way is, use of deferred objects, something like
$.when(
// make your first ajax request
).then(function(data) {
session_id = data["result"]["sessid"];
// make your second ajax call
});​
DEMO