I have the following function that works but not as I want it to since each iteration needs the results of the iteration before.
There are plenty of similar questions but I'm finding it hard to reduce the solutions down to a pattern.
How can I rewrite the following function so that each loop iteration "waits" for the one before it?
$scope.updateBarcode = function() {
var itemcodes = $scope.itemcode.split(';');
// doc is JSPDF document, fetch will add a new page to the supplied doc.
var doc;
//fetch will unshift the returned doc onto the supplied array.
var result = [];
for (var i = 0; i < itemcodes.length; i++) {
var promise = $scope.fetch(doc, itemcodes[i],result);
promise.then(function(){
doc = result[0];
if (i >= itemcodes.length) {
doc.save(itemcodes[0] + '.pdf');
};
})
};
}
You need to assign the new promise from then() to your variable so that you build up a chain:
promise = promise.then(...);
Related
I'm fetching a URL. The full response is spread over five pages.
I'm looping through each pages which returns me an array of object (please correct me if I'm wrong):
[{item_1=foo, item_2=bar, item_3=foobar, value_1=XX}, {item_1=bar, item_2=foo, item_3=barfoo, value_1=XX},etc...]
I want to consolidate all the response like if it was one big array of objects.
So far, I wrote this:
for (i = 1; i <= total_pages; i++) {
var rawResponse = UrlFetchApp.fetch(
'url',
{
method: 'GET'
})
response[i] = JSON.parse(rawResponse);
}
var g = response[1].concat(response[2], response[3],response[4],response[5]);
g contains the desired output; however, as you can see, this is not dynamic. How can I solve this? I could you the push method, but I would return me a new array with each response.
In order to make your code "dynamic" you could use the concat function inside the for-loop, for each of the pages. A possible modification of your code could look like the following, where the result variable would contain all the results:
var result = [];
for (var i = 1; i <= total_pages; i++) {
var rawResponse = UrlFetchApp.fetch(
'url',
{
method: 'GET'
}
);
var current = JSON.parse(rawResponse);
result = result.concat(current);
}
I've been looking and looking everywhere for an example of how to get this to work appropriately. I've tried using $q.all() and it doesn't work. I can't seem to get promises to work appropriately or I'm not accessing them correctly. I'm making an API call to retrieve information about movies and I want to keep them ordered by release date. The easiest way would be to keep the call in the order I make them. I order the movie ids by release date and call them in that array order. Then I want to push the data from the call to a new array. But it's instead not always doing it in the correct order. Could someone possibly tell me what I may be doing wrong?
$scope.movies = [
{url:"tt3470600", group:"m",youtube:"Vso5o11LuGU", showtimes: "times1"},
{url:"tt3521164", group:"m",youtube:"iAmI1ExVqt4", showtimes: "times2"}
];
$scope.imdb = function () {
var promises = [];
for(var i = 0; i < $scope.movies.length; i++) {
var movie = $scope.movies[i];
var options = {trailer: movie.youtube, times: $scope.times[movie.showtimes]};
var promise = $http.get('http://www.omdbapi.com/?i=' + movie.url);
promise.times = options;
promises.push(promise);
};
return $q.all(promises);
};
var x = $scope.imdb();
console.log(x);
What's returned is an object d with a key of $$state. I would love to keep the order desperately because the times I return have a date selection that I would like to keep ordered.
I think you just missed something important here which is
var deferred = q.defer(); //init promise
and also
deferred.resolve(item); // resolve the promise
besides that
don't forget to handle error cases -> use deferred.reject(item) for those
Once you have done with all your promise, save all the results into the array
var arr = [];
q.allSettled(promises).then(function(results) {
arr = results;
});
You can use $q in a func to return a promise and make the http call inside that function and then call this based on the order you desire to get the array of promises.
var ajaxcallURl = {
0: 'https://api.github.com/users?since=84',
1: 'https://api.github.com/search/users?q=tyler',
2: 'https://api.github.com/users?since=357',
3: 'https://api.github.com/users?since=19990',
4: 'https://api.github.com/search/users?q=john',
5: 'https://api.github.com/users?since=2345',
6: 'https://api.github.com/users?since=1899',
7: 'https://api.github.com/search/users?q=james',
8: 'https://api.github.com/users?since=786',
9: 'https://api.github.com/search/users?q=nicholas',
10: 'https://api.github.com/users?since=99'
}
var SomeAsyncCall = function () {
var status_deferred = $q.defer();
var requestUrl = ajaxcallURl[count];
$http.get(requestUrl).
success(function (data, status, headers, config) {
status_deferred.resolve(data);
}).error(function (errdata, status, header, config) {
//requestData call failed, pass additional data with the reject call if needed
status_deferred.reject(errdata);
});
return status_deferred.promise;
}
With this promise array you can use $q.all to resolve all those and get the results when all those promises are done.
function createPromisesArray() {
var promiseArray = [];
for (var i=0;i<10;i++){
promiseArray.push(SomeAsyncCall());
}
return promiseArray;
}
var lstPromised = createPromisesArray();
$q.all(lstPromised).then((values) => {
console.log(values[0]);
console.log(values[1]);
// ....
console.log(values[9]);
values.forEach(function (result) {
console.log(result)
});
even though $q.all executes all promises asynchronously , you can get the appropriate promise result from the array.
I have this code in angular,
$http({
method:'POST',
url :'someURL', //returns an array of urls [url1, url2, url3..]
data : dataObj
})
.then(function(response) {
var items = response.data;
var promises = [];
$scope.output =[];
items.forEach(function(el){
return promises.push($http.get(el)); //fills the promise[] array
});
var ignore = function(x) { return x.catch(function(){}); } // To ignore if promise does not get resolved (only accept responses with status 200)
var all = $q.all( promises.map(ignore) ); //chaining promises array
all.then(function success(d){
console.log($scope.output); //want the output to be ["text1", "text2", "text3"...]
});
for (var i=0; i < promises.length ; i++){
promises[i].then(success).catch(function (){
});
function success(r){
$scope.output.push(r.data.text); //{text: "text1"}
}
}
});
The result of this operation is stored in $scope.output. On executing I'm getting output as ["text2", "text3", "text1" ...] which is not in a serial fashion. My question is how I can make this execute in a serial fashion so that the output would be ["text1", "text2", "text3" ...]
Replace your last for loop with the following:
angular.forEach(promises, function(promise, index){
promise.then(success).catch(function (){});
function success(r){
$scope.output[index] = r.data.text;
}
});
Due to closure paradigm the index variable will be available in the success handler upon promise resolution no matter in which order the promises get resolved and the results will be placed to the output array in the order of the original promises.
Didn't test it, but from first view I'd say you need to put the for() loop inside the all.then().
all.then(function success(d){
console.log($scope.output);
for (var i=0; i < promises.length ; i++) {
promises[i].then(success).catch(function () { });
function success (r) {
$scope.output.push(r.data.text);
}
}
});
Because otherwise you loop through partially unresolved promises. Those that resolve earlier will skip ahead in the queue.
Having the for() loop inside the all.then() you make sure that all promises have resolved already and will add themselves to the output list when they are called with promises[i].then(success).
IMO,you should not use callbacks inside for loop. I think, it is causing this behavior. I hope it will work. No need to add last for loop.
var all = $q.all( promises.map(ignore) );
all.then(function success(d){
d.forEach(function(res){
$scope.output.push(r.data.text);
});
console.log($scope.output);
});
i have following method:
var i;
$scope.playAllSelectedSounds = function() {
try {
for( i; i < $scope.selectedSounds.length; i++) {
var fileName = $scope.selectedSounds[i].file;
var volume = $scope.selectedSounds[i].defaultVolume;
var filePath = "sounds/" +fileName+".mp3";
console.log(fileName);
MediaSrv.loadMedia(filePath).then(function(media){
console.log(media);
// !!!!!!!!!!! HERE I CANNOT GET value of the i VARIABLE
$scope.selectedSounds[i].state = 1;
// !!!!!!!!!!! HERE I CANNOT GET value of the i VARIABLE
$scope.selectedSounds[i].mediaInstance = media;
media.play();
media.setVolume(volume);
});
}
} catch(e) {
alert(JSON.stringify(e));
console.log(e);
$scope.showAlert("Error", "Error during the playing item");
}
};
Problem is that inside of the service:
MediaSrv.loadMedia(filePath).then(function(media){
I cannot get number o for cycle loop which i need to set in:
$scope.selectedSounds[i].state = 1;
Variable i is global i still cannot reach them. How can i solve it please?
It is not because i is not accessible, it is because i has run out of its limit because loadMedia is async and the value of i within the callback would become $scope.selectedSounds.length, since the for loop would have run out before the callback is invoked.
You could resolve this by using a closure variable representing the current item: You could just make use angular.forEach itself, and you don't event need to worry about accessing the right index. Instead just modify the object itself which is available as 1st argument of forEach evaluator function.
angular.forEach($scope.selectedSounds, function loadMedia(selectedSound, idx){
var fileName = selectedSound.file;
var volume = selectedSound.defaultVolume;
var filePath = "sounds/" +fileName+".mp3";
MediaSrv.loadMedia(filePath).then(function(media){
selectedSound.state = 1;
selectedSound.mediaInstance = media;
media.play();
media.setVolume(volume);
});
});
Also you forgot to initialize i in your case, which will cause your loop to not run at all.
Does it work if you create a local variable var that=i; just before your call to the promise, and then try to get "that" inside the promise return?
Otherwise try this :
for (var i in superarray){
(function(j) {
MyService.get(superarray[j].externalID).then(function(r) {
console.debug(j);
});
})(i);
}
So, I'm having issues testing an angular filter that takes an array that has previously been sorted by a group property. It uses a flag property to indicate that the item is the first observation of that group, and then false for subsequent observations.
I'm doing this to have a category header in the UI with an ng-repeat directive.
When I test the filter, the output does not return the array with the flags unless I create new objects for the return array. This is a problem, because it causes an infinite loop when running in a webpage. The code works in the webpage when it just adds a flag property to the input object.
Is there some additional step I should be taking to simulate how angular handles filters so that it outputs the proper array?
This is what my test looks like right now.
describe('IsDifferentGroup', function() {
var list, itemOne, itemTwo, itemThree;
beforeEach(module("App.Filters"));
beforeEach(function () {
list = [];
itemOne = new ListItem();
itemTwo = new ListItem();
itemThree = new ListItem();
itemOne.group = "A";
itemTwo.group = "B";
itemThree.group = "C";
list.push(itemOne);
list.push(itemOne);
list.push(itemOne);
list.push(itemOne);
list.push(itemTwo);
list.push(itemThree);
list.push(itemThree);
list.push(itemThree);
list.push(itemThree);
list.push(itemThree);
});
it('should flag the items true that appear first on the list.', (inject(function (isDifferentGroupFilter) {
expect(list.length).toBe(10);
var result = isDifferentGroupFilter(list);
expect(result[0].isDifferentGroup).toBeTruthy();
expect(result[1].isDifferentGroup).toBeFalsy();
expect(result[4].isDifferentGroup).toBeTruthy();
expect(result[5].isDifferentGroup).toBeTruthy();
expect(result[6].isDifferentGroup).toBeFalsy();
expect(result[9].isDifferentGroup).toBeFalsy();
})));
});
And here is something like the code with the filter:
var IsDifferentGroup = (function () {
function IsDifferentGroup() {
return (function (list) {
var arrayToReturn = [];
var lastGroup = null;
for (var i = 0; i < list.length; i++) {
if (list[i].group != lastGroup) {
list[i].isDifferentGroup = true;
lastAisle = list[i].group;
} else {
list[i].isDifferentGroup = false;
}
arrayToReturn.push(list[i]);
}
return arrayToReturn;
});
}
return IsDifferentGroup;
})();
Thanks!
I figured out my issue.
When I was passing the items into the list, I just pushed a pointer to an item multiple times. I was not passing in unique objects so the flag was being overridden by the following flag in the array(I think). So, I just newed up 10 unique objects using a loop, pushed them into the array and ran it through the filter. And it worked.
I'm not entirely sure my analysis is correct about the override, because itemTwo was not being flagged as unique when it was the only itemTwo in the array. But the test is working as I would expect now so I'm going to stop investigating the issue.