Develop Reference

Two requests in one time immediatly. ASP MVC + JQuery Ajax

MVC application (ASP.NET MVC, client: jquery).
Problem: The second ajax-request wait, when the first ajax request will done.
I need, when the first and the second ajax-requests executes immediatly in one time.
The page sends to server to determine the count of records (the first ajax-request), very long (~5-7 seconds).
The operator click the buttom to open the card to edit it (the second ajax-request, fast, get the Dto-model).
The user doesn't need to wait the first request, he wants to work immediatly.
As a result, in Chrome in network page, two requests in status 'pending'. The second waits the first.
Question, how can I send requests, to execute asynchronously ?
The first ajax-request:
`window.jQuery`.ajax({
type: 'POST',
url: Url.Action("GetCountBooks", "Book");
contentType: "application/json; charset=utf-8",
dataType: 'json',
data: JSON.stringify({ typeBook: "...", filter: "..." };),
success: function (data) {
// show in UI page the count of books by filter and params
},
error: function (data) {
//show error
}});
public class BookController : Controller
{
[HttpPost]
public NJsonResult GetCountBooks(string typeBook, Filter filter)
{
var data = DbProvider.GetCountBooks(typeBook, filter)
if (data.Result == ResultType.Success)
{
var count = data.Data;
return new NJsonResult
{
Data = new { Data = count }
};
}
return new NJsonResult
{
Data = new { Error = "Error while counting the books." }
};
}
}
The second ajax-request:
`window.jQuery`.ajax({
type: 'POST',
dataType: 'json',
contentType: "application/json",
url: Url.Action("GetBookById", "Book"),
data: JSON.stringify({ id: bookId }),
success: function (data) {
// show jquery dialog form to edit dto-model.
},
error: function (data) {
//show error
}});
public class BookController : Controller
{
[HttpPost]
public NJsonResult GetBookById(int id)
{
var data = DbProvider.GetBookById(id)
if (data.Result == ResultType.Success)
{
var book = data.Data;
return new NJsonResult
{
Data = new { Data = book }
};
return new NJsonResult
{
Data = new { Error = "The book is not found." }
};
}
return new NJsonResult
{
Data = new { Error = "Error while getting the book." }
};
}
}
I Cannot union ajax requests into one! The user can send various second request.

You need a fork-join splitter to fork 2 tasks and join based on some condition.
For example here is my implementation:
function fork(promises) {
return {
join: (callback) => {
let numOfTasks = promises.length;
let forkId = Math.ceil(Math.random() * 1000);
fork_join_map[forkId] = {
expected: numOfTasks,
current: 0
};
promises.forEach((p) => {
p.then((data) => {
fork_join_map[forkId].current++;
if (fork_join_map[forkId].expected === fork_join_map[forkId].current) {
if (callback) callback(data)
}
})
});
}
}}
Pass any number of async tasks (promises) into fork method and join when all are done. The done criteria here is managed by simple global object fork_join_map which tracks the results of your fork-join process (global is not good but its just an example). The particular fork-join is identified by forkId which is 0..1000 in this example which is not quite good again, but I hope you got the idea.
With jQuery you can create promise with $.when( $.ajax(..your ajax call) )
In the end you can join your promises like this
fork([
$.when( $.ajax(..your ajax call 1) ),
$.when( $.ajax(..your ajax call 2) )
]).join(() => {
// do your logic here when both calls are done
});
It's my own implementation, there may be already-written library functions for this in jQuery - I dont know. Hope this will give you a right direction at least.

The solution is to add attribute to Asp Controller: [SessionState(System.Web.SessionState.SessionStateBehavior.ReadOnly)]
http://johnculviner.com/asp-net-concurrent-ajax-requests-and-session-state-blocking/

How to pass the result of an Asynchronous function as a deffered object

i'm trying to get my head around working with Deffered objects especially in cases where you have to perform multiple asynchronous operations on every item in an array. In the code below i just want to be able to access the result of an asynchronous array after it is complete, in my case it is the results array.
To explain the code below
ListData function derives the source data which is an array that i intend to manipulate.
getPictureComplete1 perfroms an async operation (ListDataWithPicture) on every item in the array above
The idea of step 2 was to add an image url to every item in the array from Step 1 and then use the new array as an input to step 4
could be to print the images to the page or perform additional manipulations on the array
var mydeferred = $.Deferred();
var ListData = function (){
listName = 'TeamInfo';
$.ajax({
url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('"+listName+"')/items?$select=Name/Title,Name/Name,Name/Id,Name/EMail,Name/WorkPhone&$expand=Name/Id",
type: "GET",
headers: { "ACCEPT": "application/json;odata=verbose" },
success: onQuerySucceded,
error: onQueryFailed
});
return mydeferred.promise();
}
var ListDataWithPicture = function(userId, callback) {
// execute AJAX request
$.ajax({
url: _spPageContextInfo.siteAbsoluteUrl + "/_api/web/SiteUserInfoList/items?$filter=Id eq " + userId + "&$select=Picture",
type: "GET",
async: false,
headers: { "ACCEPT": "application/json;odata=verbose" },
success: function(data){
console.log("Starting async operation for " + userId);
var pictureLink = "";
var mydata = callback(data.d.results[0].Picture.Url);
return mydata
},
error: onQueryFailed
});
}
function onQuerySucceded (data){
var PeopleCompleteList = [];
for (i=0; i< data.d.results.length; i++) {
//check if the user exists if he does store the following properties name,title,workphone,email
if(data.d.results[i]['Name'] != null){
personName = data.d.results[i]['Name'].Name.split('|')[2];
userName = data.d.results[i]['Name']['Name'];
UserTitle = data.d.results[i]['Name']['Title'];
UserphoneNumber = data.d.results[i]['Name']['WorkPhone'];
UserEmail = data.d.results[i]['Name']['EMail'];
Id = data.d.results[i]['Name']['Id'];
PeopleCompleteList.push(PersonConstructor(personName, UserTitle, UserphoneNumber,UserEmail,Id));
}
}
mydeferred.resolve(PeopleCompleteList);
}
function getPictureComplete1 (data){
var def = new $.Deferred();
var results = [];
var expecting = data.length;
data.forEach(function(entry, index) {
//this is the asynchronous function
ListDataWithPicture(entry.UserId, function(result) {
results[index] = {imageUrl: result, UserId: entry.UserId, name: entry.name, Title: entry.Title, phoneNumber: entry.phoneNumber, Email: entry.Email};
//console.log(result);
if (--expecting === 0) {
// Done!
console.log("Results:", results); //this works succeffully from here
def.resolve();
return results
//mydeferred.resolve(results);
}
});
});
return mydeferred.promise();
}
$(function () {
ListData().then(function(data){
//how can i access the results array in this function after it has completed??
var value = getPictureComplete1 (data);
//the line below results undefined,which i understand because the getPictureComplete1 function may not have completed at the time
console.log(value);
});

Because this is an asynchronous operation, the only time that you have access to the array of results from your ajax call in LineData is within the scope of the onQuerySucceded function that you assigned to the success property in your ajax configuration. The function you define here will be fired after a successful response was received.
When establishing a deferred promise, you will need to define what data resolves the promise. Whatever you pass into the resolve method will be available as a parameter within a subsequent then block on your promise chain.
I'm not seeing onQuerySucceded defined in your example, but it would look something like this:
var ListData = function (){
var mydeferred = $.Deferred();
listName = 'TeamInfo';
$.ajax({
url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('"+listName+"')/items?$select=Name/Title,Name/Name,Name/Id,Name/EMail,Name/WorkPhone&$expand=Name/Id",
type: "GET",
headers: { "ACCEPT": "application/json;odata=verbose" },
success: function onQuerySuccess(data) {
mydeferred.resolve(data);
},
error: onQueryFailed
});
return mydeferred.promise();
}
Now, after a successful call, the promise will resolve with the data. So, something like this is possible:
ListData()
.then(function (data) {
// do something with the data
})
Similarly, you will want to define what are the rejection cases for your deferred promise. For example, maybe the ajax call doesn't succeed. For this, you will want to use the reject method on the deferred object.
For example:
var ListData = function (){
var mydeferred = $.Deferred();
listName = 'TeamInfo';
$.ajax({
url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('"+listName+"')/items?$select=Name/Title,Name/Name,Name/Id,Name/EMail,Name/WorkPhone&$expand=Name/Id",
type: "GET",
headers: { "ACCEPT": "application/json;odata=verbose" },
success: function onQuerySuccess(data) {
mydeferred.resolve(data);
},
error: function onQueryFailed(error) {
mydeferred.reject(error);
}
});
return mydeferred.promise();
}
This works similarly to resolve, but will resolve to any subsequent catch or fail blocks. So, something like this will work
LineData()
.then(function (data) {
// it was successful, do something with the data
})
.catch(function (error) {
// There was an error. The then block was not called.
// Do something with the error.
})
Put even more simply, you can set mydeferred.resolve and mydeferred.reject as these properties directly. Like so:
var ListData = function (){
var mydeferred = $.Deferred();
listName = 'TeamInfo';
$.ajax({
url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('"+listName+"')/items?$select=Name/Title,Name/Name,Name/Id,Name/EMail,Name/WorkPhone&$expand=Name/Id",
type: "GET",
headers: { "ACCEPT": "application/json;odata=verbose" },
success: mydeferred.resolve,
error: mydeferred.reject
});
return mydeferred.promise();
}
You will want to do something similar with your ListDataWithPicture function so that it also returns a promise with the data that you need:
var ListDataWithPicture = function(userId, callback) {
var deferred = $.Deferred();
$.ajax({
url: _spPageContextInfo.siteAbsoluteUrl + "/_api/web/SiteUserInfoList/items?$filter=Id eq " + userId + "&$select=Picture",
type: "GET",
async: false,
headers: { "ACCEPT": "application/json;odata=verbose" },
success: function(data){
deferred.resolve(data.d.results[0].Picture.Url)
},
error: deferred.reject
});
return deferred.promise();
}
This allows you to do something like this:
LineData()
.then(function (data) {
// performing on just the first result:
return ListDataWithPicture(data[0]);
})
.then(function (url) {
// do something with the result
})
.catch(function (error) {
// do something with the error
});
Because you want to perform a aynchronous operation on each of the items in your array, I'd recommend to use Promise.all which executes and resolves an array of promises.
LineData()
.then(function (data) {
// create a map of promises
var promises = data.map(function (item) {
return ListDataWithPicture(item);
});
return Promise.all(promises);
})
.then(function (urls) {
// urls will be an array of urls resolved from calling
// ListDataWithPicture on each item in the array resolved
// from above
})
.catch(function (error) {
// do something with the error
});
Here are some good resources to learn more:
http://api.jquery.com/category/deferred-object/
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all

In Angular, How to wait for finish async call then go to next object inside foreach?

I am facing a problem about angular async call inside angular.forEach.
How to wait for nested async call finished, then go to next foreach object.
For below concept example.
Suppose i insert record to database with temp code is 1200, 1201, 1202.
Now i found the problem point is first finish forEach loop by 1200, then createMember through factory, so the 3 record temp code was 1200, 1200, 1200.
how should i fix in correct loop order.
I want the sequence is
//1200
forEach 1 of $scope.xyzList -> getTempCode -> createMember -> updateTempCode,
//1201
forEach 2 of $scope.xyzList -> getTempCode -> createMember -> updateTempCode,
//1202
forEach 3 of $scope.xyzList -> getTempCode -> createMember -> updateTempCode,
Sample Concept Code as below
Suppose $scope.xyzList object list have 3 objects.
var data = {"code": "null"};
angular.forEach($scope.xyzList, function(v, k){
$http({
method: 'POST',
url: 'http://xxxx.com/getTempCode', // for example temp code: 1200
data: JSON.stringify(data),
headers: {'Content-Type': 'application/json'}
}).then(function(obj) {
$scope.createMember(obj, v);
}
})
$scope.createMember = function(obj, listVal) {
var currentCode = obj;
var cdata = {"code": currentCode};
var memberView = New MemberView();
memberView.code = obj;
memberView.name = listVal.name;
$http({
method: 'POST',
url: 'http://xxxx.com/checkCodeExist',
data: JSON.stringify(data),
headers: {'Content-Type': 'application/json'}
}).then(function(rs) {
if (rs.code == null) {
xxxxFactory.createMember($rootScope.global.systemObj, memberView)
.then(function(result){
$http({
method: 'POST',
url: 'http://xxxx.com/updateTempCode', // Temp code + 1
data: JSON.stringify(cdata),
headers: {'Content-Type': 'application/json'}
})
})
}
}
}

Instead of a forEach loop, you can use a recursive function when you need something to wait for an async process to finish. In this case, something like this:
function handleListItem(list, idx) {
$http({
method: 'POST'
, url: 'http://xxxx.com/getTempCode', // for example temp code: 1200
data: JSON.stringify(data)
, headers: {
'Content-Type': 'application/json'
}
}).then(function (obj) {
$scope.createMember(obj, list[idx], function () {
var nextItem = list[++idx]
if (nextItem) handleListItem(list, idx)
}
});
}
}
So now your createMember function needs to take an anonymous function as its third parameter, and call that once it finishes everything it's doing, something like this:
$scope.createMember = function (obj, listVal, next) {
// all of your code until here
$http({
method: 'POST'
, url: 'http://xxxx.com/updateTempCode', // Temp code + 1
data: JSON.stringify(cdata)
, headers: {
'Content-Type': 'application/json'
}
}).then(next)
}
Finally, kick everything off by calling that function with your list and the 0 index as its parameters.
handleListItem($scope.xyzlist, 0)

You can use a closure to persist your value in the callback. This way, you don't need to wait for the async call to finish. For example:
function callbackCreator(val) {
return function(obj) {
$scope.createMember(obj, val);
}
}
angular.forEach($scope.xyzList, function(v, k){
var cb = callbackCreator(v);
$http({
method: 'POST',
url: 'http://xxxx.com/getTempCode', // for example temp code: 1200
data: JSON.stringify(data),
headers: {'Content-Type': 'application/json'}
}).then(cb);

Use es6 let. Let is loop-scoped so your loop won't go into race conditions, just because the iterator is defined in every loop with its own scope. Just be careful because for (var key in obj) iterates over the prototype:
var myObj = $scope.xyzList;
for (let key in myObj) {
if (myObj.hasOwnproperty(key)) {
let v = myObj[key];
$http({
method: 'POST',
url: 'http://xxxx.com/getTempCode', // for example temp code: 1200
data: JSON.stringify(data),
headers: {'Content-Type': 'application/json'}
}).then(function(obj) {
$scope.createMember(obj, v);
}
}
}
Simple and clean. Hope it helps.

Many requests with final callback, unreliable order?

I'm trying to come up with a resource loader if you will, that will load many remote resources and then execute a final callback (like rendering a DOM based on the retrieve data from these requests).
Here's the function:
var ResourceLoader = function () {
this.requests = new Array();
this.FinalCallback;
this.Add = function (request) {
this.requests.push(request);
};
this.Execute = function() {
for (var x = 0; x < this.requests.length ; x++) {
var success = this.requests[x].success;
//if this is the last of the requests...
if (x == (this.requests.length - 1) && this.FinalCallback) {
$.when($.ajax({
url: this.requests[x].url,
dataType: 'json',
error: this.requests[x].error,
method: 'GET'
}).done(success)).then(this.FinalCallback);
}
else {
$.ajax({
url: this.requests[x].url,
dataType: 'json',
error: this.requests[x].error,
method: 'GET'
}).done(success);
}
}
};
};
And here's how I use it:
var apiUrl = Utilities.Api.GetWebApiUrl();
var loader = new Utilities.ResourceLoader();
loader.Add({
url: apiUrl + 'regions/get',
success: function (results) {
Filters.Regions = results;
}
});
loader.Add({
url: apiUrl + 'currentfactors/get/83167',
success: function (results) {
Filters.NbrEmployees = results;
}
});
loader.Add({
url: apiUrl + 'currentfactors/get/83095',
success: function (results) {
Filters.Industries = results;
}
});
loader.FinalCallback = RenderBody;
loader.Execute();
function RenderBody() {
console.log('render...');
}
Obviously, I'm expecting RenderBody to be executed last. But that's not what happening. What's ironic is that I remember doing something like that before, but lost the code... Looks like I'm having a brainfart here.

As you've tagged with promise - here's a really clean solution that uses Promise.all
this.Execute = function() {
Promise.all(this.requests.map(function(request) {
return $.ajax({
url: request.url,
dataType: 'json',
error: request.error,
method: 'GET'
}).done(request.success);
})).then(this.FinalCallback);
};
or ... using JQuery when
this.Execute = function() {
$.when.apply($, this.requests.map(function(request) {
return $.ajax({
url: request.url,
dataType: 'json',
error: request.error,
method: 'GET'
}).done(request.success);
})).then(this.FinalCallback);
};

Es6 Promise has solutions for your problem, there is no need to reinvent it unless the loading of resource groups is a specific goal to abstract. Set up a Promise object for each resource request, using the constructor to assign the resolve and reject callbacks appropriately for the XHR. Keep a collection (any Iterable will do) of individualPromise.then(individualCallback) results. Your final product is obtained by Promise.all(collectionOfPromises).then(finalCallback).

Angular Promise Response Checking

I am doing some http calls in Angular and trying to call a different service function if an error occurs. However, regardless of my original service call function return, the promise it returns is always "undefined". Here is some code to give context:
srvc.sendApplicantsToSR = function (applicant) {
var applicantURL = {snip};
var promise = $http({
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
},
method: 'POST',
url: applicantURL,
data: applicant
})
.success(function (data) {
return data;
})
.error(function (error) {
return [];
});
return promise;
};
Then, in the controller:
for (var applicant in $scope.applicants) {
$scope.sendATSError($scope.sendApplicantsToSR($scope.applicants[applicant]), applicant);
}
$scope.sendATSError = function (errorCheck, applicantNumber) {
if (angular.isUndefined(errorCheck)) {
console.log(errorCheck);
AtsintegrationsService.applicantErrorHandling($scope.applicants[applicantNumber].dataset.atsApplicantID);
}
};
However, it is always sending errors because every response is undefined. How can I differentiate between the two returns properly? Thank you!

Looking at angular documentation, the sample code is
$http({
method: 'GET',
url: '/someUrl'
}).then(function successCallback(response) {
// this callback will be called asynchronously
// when the response is available
}, function errorCallback(response) {
// called asynchronously if an error occurs
// or server returns response with an error status.
});
based on that - your first code snippet should be
srvc.sendApplicantsToSR = function(applicant) {
var applicantURL = {
snip
};
return $http({
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
},
method: 'POST',
url: applicantURL,
data: applicant
});
};

As others have said, $http's .success() and .error() are deprecated in favour of .then().
But you don't actually need to chain .then() in .sendApplicantsToSR() as you don't need (ever) to process the successfully delivered data or to handle (at that point) the unsuccessful error.
$scope.sendApplicantsToSR = function (applicant) {
var applicantURL = {snip};
return $http({
headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
method: 'POST',
url: applicantURL,
data: applicant
});
};
Now, in the caller (your line of code in the for loop), a promise is returned (not data) and that promise will, on settling, go down its success path or its error path. Exactly what happens on these paths is determined entirely by the callback functions you write in one or more chained .thens .
So what you need to write is a kind of inside-out version of what's in the question - with $scope.sendApplicantsToSR() on the outside and $scope.sendATSError() on the inside - and linked together with a .then().
for (var prop in $scope.applicants) {
var applicant = $scope.applicants[prop];
$scope.sendApplicantsToSR(applicant).then(null, $scope.sendATSError.bind(null, applicant));
}
// Above, `null` means do nothing on success, and
// `function(e) {...}` causes the error to be handled appropriately.
// This is the branching you seek!!
And by passing applicant, the error handler, $scope.sendATSError() will simplify to :
$scope.sendATSError = function (applicant) {
return AtsintegrationsService.applicantErrorHandling(applicant.dataset.atsApplicantID); // `return` is potentially important.
};
The only other thing you might want to know is when all the promises have settled but that's best addressed in another question.

You should return your promisse to be handled by the controller itself.
Simplifying:
.factory('myFactory', function() {
return $http.post(...);
})
.controller('ctrl', function(){
myFactory()
.success(function(data){
// this is your data
})
})
Working example:
angular.module('myApp',[])
.factory('myName', function($q, $timeout) {
return function() {
var deferred = $q.defer();
$timeout(function() {
deferred.resolve('Foo');
}, 2000);
return deferred.promise;
}
})
.controller('ctrl', function($scope, myName) {
$scope.greeting = 'Waiting info.';
myName().then(function(data) {
$scope.greeting = 'Hello '+data+'!';
});
});
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="myApp" ng-controller="ctrl">
{{greeting}}!
</div>