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Capturing async call response in dojo/aspect before

Trying to capture response of a async request in dojo/aspect before() event before handing it off to the original method as below:
aspect.before(ecm.model.SearchTemplate.prototype, "_searchCompleted", function(response, callback, teamspace){
var args = [];
if(response.num_results==0 && isValidQuery){
var args = [];
var requestParams = {};
requestParams.repositoryId = this.repository.id;
requestParams.query = query;
Request.invokePluginService("samplePlugin", "sampleService",
{
requestParams: requestParams,
requestCompleteCallback: lang.hitch(this, function(resp) { // success
//call stack doesnt enter this code block before returning params to the original
//function
resp.repository = this.repository;
args.push(resp);
args.push(callback);
args.push(teamspace);
})
}
);
return args; //args is empty as the response is not captured here yet.
}
});

aspect.around is what you're looking for. It will give you a handle to the original function you can call at will (thus, async at any time you're ready - or never at all).
aspect.around(ecm.model.SearchTemplate.prototype, "_searchCompleted", function advisingFunction(original_searchCompleted){
return function(response, callback, teamspace){
var args = [];
if(response.num_results==0 && isValidQuery){
var args = [];
var requestParams = {};
requestParams.repositoryId = this.repository.id;
requestParams.query = query;
Request.invokePluginService("samplePlugin", "sampleService",
{
requestParams: requestParams,
requestCompleteCallback: lang.hitch(this, function(resp) { // success
//call stack doesnt enter this code block before returning params to the original
//function
resp.repository = this.repository;
args.push(resp);
args.push(callback);
args.push(teamspace);
original_searchCompleted.apply(this,args);
})
}
);
}
}
});

Can I get a value returned from a $.Deferred() that can be used in the display?

I am using the $.Deferred method to try and get a function to load some Json, work on the results, then pass the value back to another function that will use the result (in this case I expect an integer). For some reason I can get this integer displayed using either alert or console.log functions, but when it comes to using it as the return value of the actual function the code falls over and returns undefined.
For reference here's my code:
function NewValue(){
var dataPromise = GetDataFromJson();
dataPromise.done(function(data){
//note both console.log(data) and alert(data) deliver the correct result here
return data;
});
}
function GetDataFromJson() {
var jsonData;
var deferred = $.Deferred();
d3.json("http://localhost:8000/pipeline.json", function(dataFromServer){
jsonData = dataFromServer;
headers = ["Won"];
myTotal = 0;
chunks = (headers.map(function(priceRange) {
return jsonData.map(function(d) {
return {y: +d[priceRange]};
});
}));
var myTarget = 10000000;
chunks.forEach( function (arrayItem)
{
var l = 12;
for(var i = 0; i < l; i++) {
myTotal += arrayItem[i].y;
};
});
myTotal = myTotal/myTarget*100;
deferred.resolve(myTotal);
});
return deferred.promise();
}
Is it ever possible to return the value from GetDataFromJson() and use it, or will I only ever be able to log it to the console?
EDIT after reading through the answer the only way to do this is to call the gauge update function within my GetDataFromJson call - all these promises were seemingly pointless distractions from just passing the right info across:
function GetDataFromJson(f) {
var jsonData;
var deferred = $.Deferred();
d3.json("http://localhost:8000/pipeline.json", function(dataFromServer){
jsonData = dataFromServer;
if( f == "Current"){
console.log('c');
headers = ["Won"]
} else if( f == "Projected"){
console.log('p');
headers = ["Won", "Prospecting", "Qualifying", "Demonstrating", "Negotiating"]
}
else {
alert('An error has occured')
};
myTotal = 0;
chunks = (headers.map(function(priceRange) {
return jsonData.map(function(d) {
return {y: +d[priceRange]};
});
}));
var myTarget = 10000000;
chunks.forEach( function (arrayItem)
{
var l = 12;
for(var i = 0; i < l; i++) {
myTotal += arrayItem[i].y;
};
});
myTotal = myTotal/myTarget*100;
gauge5.update(myTotal);
deferred.resolve(myTotal);
});
return true;
}
Now I call GetDataFromJson() directly from a click on a radio button, and pass either "Current" or "Projected" inside that call so the right data is shown. Feels stupid that I've wasted a week studying this, but hopefully this answer will help others. You can't extract data from these promises but you can call another function (in my case gauge5.update) and send it the value you want to use.

You are returning 'data' inside callback, not in function NewValue. NewValue should return promise and caller of NewValue should assign a callback on completion of this promise.
function NewValue(){
var defer = $.Deferred();
var dataPromise = GetDataFromJson();
dataPromise.done(function(data){
//note both console.log(data) and alert(data) deliver the correct result here
deferred.resolve(data);
});
return deferred.promise();
}
NewValue()
.done(function(data){
// do whatever
})
I am assuming you want to process the data further in NewValue function, else why can't you directly call GetDataFromJson?

Return result from a javascript callback (node.js)

I know this question have been asked many times, but I can't make it work.
Here is my situation. I had a string called data, and I want to unshorten all the link inside that string.
Code:
var Bypasser = require('node-bypasser');
var URI = require('urijs');
var data = 'multiple urls : http://example.com/foo http://example.com/bar';
var result = URI.withinString(data, function(url) {
var unshortenedUrl = null;
var w = new Bypasser(url);
w.decrypt(function(err, res) {
// How can I return res ?
unshortenedUrl = res;
});
// I know the w.descrypt function is a asynchronous function
// so unshortenedUrl = null
return unshortenedUrl;
});
Let's me walk you through the code.
URI.withinString will match all the URLs in data, manipulate it and return the result.
You can view an example from URI.js docs
What I want to with these URLs is to unshorten all of them using node-passer.
This is from node-bypasser document:
var Bypasser = require('node-bypasser');
var w = new Bypasser('http://example.com/shortlink');
w.decrypt(function(err, result) {
console.log('Decrypted: ' + result);
});
This is the result that I want multiple urls : http://example.com/foo_processed http://example.com/bar_processed
I created a notebook at tonicdev.com
Solution
var getUrlRegEx = new RegExp(
"(^|[ \t\r\n])((ftp|http|https|gopher|mailto|news|nntp|telnet|wais|file|prospero|aim|webcal):(([A-Za-z0-9$_.+!*(),;/?:#&~=-])|%[A-Fa-f0-9]{2}){2,}(#([a-zA-Z0-9][a-zA-Z0-9$_.+!*(),;/?:#&~=%-]*))?([A-Za-z0-9$_+!*();/?:~-]))"
, "g"
);
var urls = data.match(getUrlRegEx);
async.forEachLimit(urls, 5, function (url, callback) {
let w = new Bypasser(url);
w.decrypt(function (err, res) {
if (err == null && res != undefined) {
data = data.replace(url, res);
callback();
}
});
}, function(err) {
res.send(data);
});

You don't really understand what callback is. The callback serves to allow asynchronous code to run without Javascript waiting for it. If you were less lazy and added some debug in your code:
console.log("Started parsing");
var result = URI.withinString(data, function(url) {
console.log("URL parsed (or whatever)");
var unshortenedUrl = null;
var w = new Bypasser(url);
w.decrypt(function(err, res) {
// How can I return res ?
unshortenedUrl = res;
});
// I know the w.descrypt function is a asynchronous function
// so unshortenedUrl = null
return unshortenedUrl;
});
console.log("Call to library over");
You would (most likely) see messages in this order:
Started parsing
Call to library over
URL parsed (or whatever)
The answer: Callback is not guaranteed to run before any code you execute after assigning it. You can't put data in your result variable because the data might not be fetched yet.

status.success being called before my function is done

In my Parse background job, I want both the processUser(user); and matchCenterComparison(eBayResults); functions to be called before calling status.success.
I currently have matchCenterComparison(eBayResults); being returned at the end of processUser(user);, as you can see below.
I figured that since it's returned in processUser(user);, and status.success isn't called until after that function is done, it would therefore wait until matchCenterComparison(eBayResults); is finished before calling it. This doesn't seem to be the case.
In the Parse forums, I was told that I need to have the matchCenterComparison function return a Promise, and make sure that the function call is also part of my main promise chain so that the background job waits till it completes before status.success is called. I'm having trouble figuring out the correct syntax to accomplish this, since I can't return two functions in a row in userQuery.each.
Main Promise Chain:
Parse.Cloud.job("MatchCenterBackground", function(request, status) {
var usersQuery = new Parse.Query(Parse.User);
usersQuery.each(function (user) {
return processUser(user);
}).then(function() {
status.success("background job worked brah!");
}, function(error) {
status.error(error);
});
});
processUser function:
function processUser(user) {
// ... code to setup per-user query ...
var matchCenterItem = Parse.Object.extend("matchCenterItem");
var query = new Parse.Query(matchCenterItem);
// easy way to share multiple arrays
var shared = {
promises: [],
searchTerms: [],
};
return query.find().then(function(results) {
// process results, populate shared data (promises and searchTerms)
console.log('matchCenterItem query results:' + results);
if (results.length > 0) {
console.log('we have entered the matchcenteritem query');
for (i = 0; i < results.length; i++) {
console.log('we have also entered the loop inside the matchCenterItem query');
// later in your loop where you populate promises:
var searchTerm = results[i].get('searchTerm');
// add it to the array just like you add the promises:
shared.searchTerms.push(searchTerm);
url = 'http://svcs.ebay.com/services/search/FindingService/v1';
//push function containing criteria for every matchCenterItem into promises array
shared.promises.push((function() {
if (results[i].get('itemLocation') == 'US')
{
console.log('americuh!');
var httpRequestPromise = Parse.Cloud.httpRequest({
url: url,
params: {// httprequest params in here}
});
}
else if (results[i].get('itemLocation') == 'WorldWide')
{
console.log('Mr worlwide!');
var httpRequestPromise = Parse.Cloud.httpRequest({
url: url,
params: {// httprequest params in here}
});
}
return httpRequestPromise;
})());
}
}
//buildEbayRequestPromises(results, shared);
}).then(function() {
// process promises, return query promise
return Parse.Promise.when(shared.promises).then(function() {
// process the results of the promises, returning a query promise
// ... code here ...
console.log('were in the when.then of promise');
var eBayResults = [];
for (var i = 0; i < arguments.length; i++) {
var httpResponse = arguments[i];
// since they're in the same order, this is OK:
var searchTerm = shared.searchTerms[i];
// pass it as a param:
var top3 = buildEbayRequestPromises(httpResponse.text, searchTerm);
eBayResults.push(top3);
}
return matchCenterComparison(eBayResults);
});
});
}
matchCenterComparison function:
function matchCenterComparison(eBayResults) {
if (eBayResults.length > 0) {
console.log('yes the ebay results be longer than 0');
//Query users MComparisonArray with these criteria
var mComparisonArray = Parse.Object.extend("MComparisonArray");
var mComparisonQuery = new Parse.Query(mComparisonArray);
mComparisonQuery.contains('Name', 'MatchCenter');
//mComparisonQuery.contains("MCItems", eBayResults);
console.log('setup query criteria, about to run it');
mComparisonQuery.find({
success: function(results) {
console.log('MatchCenter comparison results :' + results);
// No new items
if (results.length > 0) {
console.log("No new items, you're good to go!");
}
// New items found
else if (results.length === 0) {
console.log('no matching mComparisonArray, lets push some new shit');
//replace MCItems array with contents of eBayResults
Parse.Object.destroyAll(mComparisonArray);
var newMComparisonArray = new mComparisonArray();
newMComparisonArray.set('Name', 'MatchCenter');
newMComparisonArray.set('MCItems', eBayResults);
//newMComparisonArray.set("parent", Parse.User());
console.log('yala han save il hagat');
// Save updated MComparisonArray
newMComparisonArray.save().then({
success: function() {
console.log('MComparisonArray successfully created!');
//status.success('MComparisonArray successfully created!');
},
error: function() {
console.log('nah no MComparisonArray saving for you bro:' + error);
//status.error('Request failed');
}
});
//send push notification
}
console.log('MatchCenter Comparison Success!');
},
error: function(error) {
console.log('nah no results for you bro:' + error);
}
});
}
}

Trying to get an async DB request to work in Angular, "Cannot call method then of undefined"

I'm building a PhoneGap app using AngularJS + an SQLite database. I am having a classic "How does asynchronous work" Angular problem with a database query, getting error "Cannot call method then of undefined". I am hoping someone can help me to see the error of my ways.
Here's my query function. Every alert() in here returns meaningful data indicating that the transaction itself is successful:
.factory('SQLService', ['$q', '$rootScope', 'phonegapReady',
function ($q, $rootScope, phonegapReady) {
function search(query) {
alert("Search running with " + query);
var promise = db.transaction(function(transaction) {
var str = "SELECT category, id, chapter, header, snippet(guidelines, '<b>', '</b>', '...', '-1', '-24' ) AS snip FROM guidelines WHERE content MATCH '" + query + "*';";
transaction.executeSql(str,[], function(transaction, result) {
var resultObj = {},
responses = [];
if (result != null && result.rows != null) {
for (var i = 0; i < result.rows.length; i++) {
resultObj = result.rows.item(i);
alert(resultObj.category); //gives a meaningful value from the DB
responses.push(resultObj);
}
} else {
//default content
}
},defaultNullHandler,defaultErrorHandler);
alert("End of transaction");
});
// Attempting to return the promise to the controller
alert("Return promise"); //this alert happens
return promise;
}
return {
openDB : openDB,
search: search
};
}]);
And in my controller, which gives the "Cannot call method then of undefined" error:
$scope.search = function(query) {
SQLService.search(query).then(function(d) {
console.log("Search THEN"); //never runs
$scope.responses = d; //is never defined
});
}
Thanks to the accepted answer, here is the full working code.
Service
function search(query) {
var deferred = $q.defer();
db.transaction(function(transaction) {
var str = "SELECT category, id, chapter, header, snippet(guidelines, '<b>', '</b>', '...', '-1', '-24' ) AS snip FROM guidelines WHERE content MATCH '" + query + "*';";
transaction.executeSql(str,[], function(transaction, result) {
var resultObj = {},
responses = [];
if (result != null && result.rows != null) {
for (var i = 0; i < result.rows.length; i++) {
resultObj = result.rows.item(i);
responses.push(resultObj);
}
} else {
resultObj.snip = "No results for " + query;
responses.push(resultObj)
}
deferred.resolve(responses); //at the end of processing the responses
},defaultNullHandler,defaultErrorHandler);
});
// Return the promise to the controller
return deferred.promise;
}
Controller
$scope.search = function(query) {
SQLService.search(query).then(function(d) {
$scope.responses = d;
});
}
I can then access the responses in the template using $scope.responses.

The question here is: what does db.transaction return.
From the way you're using it, I'm guessing it's some 3rd-party code that doesn't return a promise.
Assuming that you're using it correctly (your alert shows the right results), you need to actualy use $q to get the promise working.
Something like this:
function search(query) {
// Set up the $q deferred object.
var deferred = $q.defer();
db.transaction(function(transaction) {
transaction.executeSql(str, [], function(transaction, result) {
// do whatever you need to do to the result
var results = parseDataFrom(result);
// resolve the promise with the results
deferred.resolve(results);
}, nullHandler, errorHandler);
});
// Return the deferred's promise.
return deferred.promise;
}
Now, in your controller, the SQLService.search method will return a promise that should get resolved with the results of your DB call.

You can resolve multiple promises. Pass the array of queries as args
function methodThatChainsPromises(args,tx){
var deferred = $q.defer();
var chain = args.map(function(arg){
var innerDeferred = $q.defer();
tx.executeSql(arg,[],
function(){
console.log("Success Query");
innerDeferred.resolve(true);
},function(){
console.log("Error Query");
innerDeferred.reject();
}
);
return innerDeferred.promise;
});
$q.all(chain)
.then(
function(results) {
deferred.resolve(true)
console.log("deffered resollve"+JSON.stringify(results));
},
function(errors) {
deferred.reject(errors);
console.log("deffered rejected");
});
return deferred.promise;
}