I am making $http request to multiple environment and processing after I get all the responses. I am using the code below:
$q.all(Object.keys($rootScope.envs).map(request)).then(function(res){
var results = {};
for (var env in res) {
results[env] = res[env].data;
}
}, function(err){
console.error(err);
});
function request(env) {
return $http.get(callService.getDomainUrl()+'/'+$rootScope.envs[env]+ '/hosts.json');
}
The above code works fine, but the results object looks like below:
{
0: {data:{}},
1: {data:{}},
2: {data:{}},
3: {data:{}}
}
I want the corresponding response for each key and the results should be like
{
env1: {data:{//data for env1}},
env2: {data:{//data for env2}},
env3: {data:{//data for env3}},
env4: {data:{//data for env4}},
}
How to map the corresponding response to the key? Please let me know how to get this as this is asynchronous request. Should I have something from the API to know which env the API is coming from?
I think the simplest way would be to push the result handling into the request function, that way you still have the 'env' value in scope.
var results = {};
$q.all(Object.keys($rootScope.envs).map(request)).then(function(res){
// Do something with 'results' here.
}, function(err){
console.error(err);
});
function request(env) {
return $http.get(callService.getDomainUrl()+'/'+$rootScope.envs[env]+ '/hosts.json')
.then(function(res) { results[env] = res.data; return env; });
}
Another option would be to replace my return env with return [env, res.data] and then you can go back to creating the results object as in your original code.
The important thing here is to remember you can handle the $http.get promises individually as well as using the promises from the call to then in $q.all.
Related
I'm new to both react and firebase. I'm trying to get a string of file names (just as a continuous string for right now) from a particular folder in the firebase storage bucket. My code is as follows:
getFilesList(){
var toReturn="";
toReturn+="Testing";
var storage = firebase.app().storage(".....");
var storageRef = storage.ref();
var listRef = storageRef.child("/slides/1HdDPbTarLBxzllDlA3H/Lecture1/");
listRef.listAll().then(function(result) {
result.items.forEach(function(imageRef) {
toReturn+=this.getImageString(imageRef);
});
}).catch(function(error) {
toReturn+="error1";
});
return toReturn;
}
getImageString(imageRef) {
var toReturn="T1";
imageRef.getDownloadURL().then(function(url) {
var toReturn=url.toString();
}).catch(function(error) {
toReturn+="error2";
});
return toReturn;
}
I'm not getting any errors, but the return string is blank (aside from the 'Testing' prefix). The folder has about 20 jpg files, but it seems as though it isn't seeing that they are there. I did some research online about it, but I'm still not sure why my code isn't working. Please help me to know why this isn't working?
Thank you,
Jared
This isn't a problem with your framework, it's a problem with asynchronous code.
See, toReturn will eventually update with the results of that function call. The problem is that the caller of this function receives the array immediately, before any of the code in .then has a chance to touch it.
Even if the promise resolves instantly, the code above it will have already executed. Promises get put on a queue where the top item only executes after the current synchronous code has finished.
What getFilesList needs to do is return a Promise that the caller can then attach to in order to specify its own behaviour:
getFilesList(){
var toReturn="";
toReturn+="Testing";
var storage = firebase.app().storage(".....");
var storageRef = storage.ref();
var listRef = storageRef.child("/slides/1HdDPbTarLBxzllDlA3H/Lecture1/");
listRef.listAll().then(function(result) {
result.items.forEach(function(imageRef) {
toReturn+=this.getImageString(imageRef);
});
return toReturn;
}).catch(function(error) {
toReturn+="error1";
return toReturn;
});
And in the caller:
getFilesList.then(filesList => console.log(filesList))
I am using meteor/react for learning facebook graph api.
I want to access users' post on facebook timeline and display them on screen. How can that be done?
With the guidance of the solution provided here [How to perform common FB actions using Meteor?. I have tried the following code: server.js
Meteor.methods({
'seePost' : function(){
var graph=Npm.require('fbgraph');
if(Meteor.user().services.facebook.accessToken){
graph.setAccessToken(Meteor.user().services.facebook.accessToken);
var future = new Future();
var onComplete = future.resolver();
graph.get('/me/feed',function(err,result) {
console.log(result);
return onComplete(err,result);
})
Future.wait(future);
}
else{
return false;
}
}
});
client side code :
Meteor.call("seePost", function(err,result) {
if(err) console.log("error" , err);
else console.log("RES", result);
});
I expect the result displayed in the client side console since I want to show the users the posts on his/er timeline, But I get following output :
RES, undefined
You can do it using await and Meteor.callAsync
Basically the client code waits for the call to complete, and gives you the returned data
const result = await Meteor.callAsync("seePost");
Errors should be handled with a try..catch block
If you use fibers/future, you need to return something with "future".
const future = new Future();
// some code getting result or something
future.return(something);
return future.wait();
this will return something in the callback from client call.
try this code, when you're using fibers you need to "wait" for the response
Meteor.methods({
'seePost': function () {
var graph = Npm.require('fbgraph');
if (Meteor.user().services.facebook.accessToken) {
graph.setAccessToken(Meteor.user().services.facebook.accessToken);
var future = new Future();
var onComplete = future.resolver();
graph.get('/me/feed', function (err, result) {
console.log(result);
if (err) {
return future.return(false);
} else {
return future.return(result);
}
})
return future.wait();
}
return false;
}
});
I have this problem with kinvey backend,
I'm trying to fetch data from my collection but it doesn't work for me. here is my code :
var query = new $kinvey.Query();
query.equalTo('_id', '5909e8084c68b1ef74fa4efc');
var dataStore = $kinvey.DataStore.collection('User1Bases', $kinvey.DataStoreType.Network);
var stream = dataStore.find(query);
stream.subscribe(function onNext(entity) {
// ...
}, function onError(error) {
// ...
}, function onComplete() {
//...
});
Can you help me please
If you let run the code you have posted then consider four things:
Make sure you have Kinvey implemented:
<script src="https://da189i1jfloii.cloudfront.net/js/kinvey-html5-sdk-3.10.2.min.js"></script>
Make sure you have initialized the Kinvey service before:
// Values shown in your Kinvey console
Kinvey.init({
appKey: '<your_appKey>',
appSecret: 'your_appSecret'
});
Make sure you are logged in with a user that has the rights to read your collection (should be fine using the All Users role (default)):
var promise = Kinvey.User.login('<username>', '<password>')
.then(function() {
console.log ("You are logged in");
})
.catch(function(error) {
console.log (error);
});
Output the return result to see whats coming back. To make sure you do the query AFTER successful login, paste you query inside the .then function of login.
I'm not sure if your query is valid unter 3.x since a lot has changed and I'm not working with older Kinvey versions.
So that all together would look like this:
// Initialize Kinvey
Kinvey.init({
appKey: '<your_appKey>',
appSecret: 'your_appSecret'
});
// Login with already registered user
var promise = Kinvey.User.login('<username>', '<password>')
.then(function() {
console.log ("You are logged in");
// Your query
var query = new $kinvey.Query();
query.equalTo('_id', '5909e8084c68b1ef74fa4efc');
var dataStore = $kinvey.DataStore.collection('User1Bases', $kinvey.DataStoreType.Network);
var stream = dataStore.find(query);
stream.subscribe(function onNext(entity) {
// Output of returning result
console.log (entity);
// ...
}, function onError(error) {
// ...
}, function onComplete() {
//...
});
})
.catch(function(error) {
console.log (error);
});
There are now three return sets possible:
Nothing (as you say) -> Something missing/wrong in the code (compare yours with mine)
Empty array: Your query didn't find anything, adapt the search value(s)
One or more entries in the array -> All fine, what you were looking for!
Hope that helps!
When querying by _id there is a built in method: http://devcenter.kinvey.com/angular/guides/datastore#FetchingbyId
Try switching to var stream = dataStore.findById('entity-id');
Also check to make sure you don't have any preFetch or postFetch BL that is interfering with the query.
I'm looking to create an array of functions to call dynamically, which will be later used in the Q.all([]) promise call.
For example;
//data is previously generated
var promiseArray = [];
for (var i = 0; i < data.length; i++){
promiseArray.push(functionCall(data[i]))
}
Q.all(promiseArray).then(function(){
//Do something
})
How would I push to the array without calling the function until the Q.all statement? I don't want to call it in the for loop as it will not catch any errors and I can't process the response further.
EDIT:
So to clarify my problem (as I don't think I was as clear as I should have been), here is a solution for a static data length of say 3;
//data is previously generated
var data = [12432432,4324322392,433324323];
//Each function call can happen in parallel or series as its an external POST to an API
//I'm not bothered about speed for this application (as its low throughput) and can wait a few seconds for each
// response
//FunctionCall returns a promise
functionCall(data[0]).then(function(){
//Log success / failure to mongo
});
functionCall(data[1]).then(function(){
//Log success / failure to mongo
});
functionCall(data[2]).then(function(){
//Log success / failure to mongo
});
//OR
functionCall(data[0]).then(function(){
//Log success/failure to mongo
functionCall(data[1]).then(function(){
//Log success/failure to mongo
functionCall(data[2]).then(function(){
//Log success/failure to mongo
});
});
});
But I wont know the length of data until runtime
If I understand correctly, you want to call functionCall for an array of items, and have Q.all resolve once all the promises returned by functionCall have completed regardless if they resolve or reject - if you don't care about the results (as you don't seem to in your code) simply handle the rejection in the promise you push - i.e.
var promiseArray = [];
for (var i = 0; i < data.length; i++) {
promiseArray.push(functionCall(data[i]).then(function(result) {
// log success
return logToMongoFunction(result);
}, function(error) {
// log failure
return logToMongoFunction(error);
}).catch(function(error) {
// catch and ignore any error thrown in either logToMongoFunction above
return;
}));
}
Q.all(promiseArray).then(function () {
//Do something
});
Note: the above can be simplified to
Q.all(data.map(function (item) {
return functionCall(item).then(function(result) {
// log success
return logToMongoFunction(result);
}, function(error) {
// log failure
return logToMongoFunction(error);
}).catch(function(error) {
// catch and ignore any error thrown in either logToMongoFunction above
return;
});
})).then(function() {
//Do something
});
the edited question suggests you can perform the actions in series also - in series it would be
data.reduce(function(promise, item) {
return promise.then(function() {
return functionCall(item).then(function(result) {
// log success
return logToMongoFunction(result);
}, function(error) {
// log failure
return logToMongoFunction(error);
}).catch(function(error) {
// catch and ignore any error thrown in either logToMongoFunction above
return;
});
});
}, Promise.resolve()).then(function() {
// all done
});
instead of Promise.resolve() you could use whatever Q has as an equivalent that creates a resolved promise
logToMongoFunction would log to mongo and needs to return a promise if you need to wait for that to finish before processing the next data item. If you do not need to wait for the mongo logging to complete then there's no need for that function to return a promise
i will recommend using Promise.mapSeries or async library for this because its very easy to catch errors. One more thing looping using a for loop doesnt seems to be good approach if you have database calls in the callback because that might flush the calls to the database and node.js can have memory issues or node.js wont be able to entertain any other request because it will be busy entertaining the request in the for loop. so its always good to run loop serially or limit the numer of parallel executions at a time.
please see example below
This will run Array serially one at a time when 1st one completes execution next will be called
async.eachOfSeries(data, function(dataInstance, key, next) {
functionCall(dataInstance).then(function(){
next();
}).catch(funtion(err){
next(err);
})
}, function() {
//iteration completed
});
OR
async.eachOfSeries(data, function(dataInstance, key, next) {
functionCall(dataInstance, function(err , result){
if(err)
{
console.log(err);
next(err);
}
else
next();
});
}, function() {
//iteration completed
});
In my angular app I want to make changes to several locations in my firebase with a mix of transactions and set. I have written a promise chain with a little help. Now I need to handle any errors that may occur.
In the event of an error on any of the promises I would want to roll back any changes made in firebase (the successful promises) and alert the user to the failure.
Current code below
$scope.addNewPost = function() {
var refPosts = new Firebase(FBURL).child('/posts').push();
// Get tags into array for incrementing counters
var tags = $scope.post.tags.split(', ');
var allPromises = [];
// Iterate through tags and set promises for transactions to increment tag count
angular.forEach(tags, function(value, index){
var dfd = $q.defer();
var refTag = new Firebase(FBURL).child('/tags/' + value);
refTag.transaction( function (current_value) {
return current_value + 1;
}, function(error, committed, snapshot) {
if (committed) {
dfd.resolve( snapshot );
} else {
dfd.reject( error );
}
});
allPromises.push( dfd.promise );
});
// Add promise for setting the post data
var dfd = $q.defer();
refPosts.set( $scope.post, function (error) {
if (error) {
dfd.reject(error);
} else {
dfd.resolve('post recorded');
}
});
allPromises.push( dfd.promise );
$q.all( allPromises ).then(
function () {
$scope.reset(); // or redirect to post
},
function (error) {
// error handling goes here how would I
// roll back any data written to firebase
alert('Error: something went wrong your post has not been created.');
}
);
};
So what I need to know is how do I roll back any changes that happen to my firebase data in the event that one of these promises fail. There could be any number of updates happening in firebase. (for example: 3 tags being incremented via transaction and the post data being set)
How would I write the failure function to calculate what was successful and undo it? If this is this even possible.
--------------- sub question from original post has been solved ---------------
Also how do you force errors? I've tried setting a variable like below but it doesn't seem to work, is there something wrong with my .then?
refPosts.set( $scope.post, function (error) {
var forceError = true;
if (forceError) {
dfd.reject(forceError);
} else {
dfd.resolve('post recorded');
}
allPromises.push( dfd.promise );
});
There are two instances of this line, and they are both in the wrong place:
allPromises.push( dfd.promise );
In the first block, it should be in the last statement in the forEach callback, not in the transaction callback.
In the second block, it should be after the call to set(), not in the callback.
The way your code is written now, $q.all() is getting an empty array of promises. That could also be what's interfering with the forceError test you're attempting.