In the following code, the controller runs a function in a service that logs "object was destroyed". That function returns a promise.
On the .then() of that promise, in the controller, it logs "deleted"
"object was destroyed" should be logged first, and then (in the.then()) it should log "deleted". Unfortunately, it seems as if "deleted" is logged first.
It seems as if the .then() of the promise is ran before the function completes.
app.js
this.deleteData = function (db, objectId) {
var database = Parse.Object.extend(db);
var query = new Parse.Query(database);
return query.get(objectId, {
success: function (result) {
result.destroy({
success: function (result) {
console.log("object was destroyed");
},
error: function (result, err) {
console.log("object was not destroyed");
console.log(err);
}
});
},
error: function (result, err) {
console.log(err);
}
});
}
Controller
function ResourcesCtrl ($scope, globalFunctions, CRUD) {
$scope.deleteResource = function (objectId) {
CRUD.deleteData('resources', objectId).then(function (result2) {
console.log("deleted");
refreshResources();
});
}
The call to result.destroy() inside the success call back is asynchronous so therefore your success function will continue on and return and then promise that you return from your deleteData function will be resolved. All this before callback for result.destroy().
Ultimately you want deleteData to return the promise from result.destroy().
Here is a rough example
this.deleteData = function (db, objectId) {
var database = Parse.Object.extend(db);
var query = new Parse.Query(database);
return query.get(objectId).then(function (result) {
return result.destroy().then(function (result) {
console.log("object was destroyed");
}, function (err) {
console.log("object was not destroyed");
console.log(err);
});
}, function (err) {
console.log(err);
});
};
and then if you don't need the logging in can be even more succinct
this.deleteData = function (db, objectId) {
var database = Parse.Object.extend(db);
var query = new Parse.Query(database);
return query.get(objectId).then(function (result) {
return result.destroy();
});
};
Related
getting undefined all the time "main.js":
var dbAccess = require('../dao/dbAccess');
dbaInstance = new dbAccess();
var wordPool = dbaInstance.getWordPool();
console.log (wordPool);
and "dbAccess.js" contains:
var DatabaseAccess = function() {}
DatabaseAccess.prototype.getWordPool = function () {
RoundWord.find({},'words decoys', function(err, wordPoolFromDB) {
if (err) throw err;
//console.log(wordPoolFromDB); -working ok
return (wordPoolFromDB);
});
}
module.exports = DatabaseAccess;
why is it not working?
DatabaseAccess.prototype.getWordPool is not returning any result.
Since you are using an asynchronous function, you need do one of these things:
a) Take a callback as parameter and invoke the callback with a result
DatabaseAccess.prototype.getWordPool = function (cb) {
RoundWord.find({}, 'words decoys', function(err, results) {
if (err) {
return cb(err, null);
}
cb(null, results);
});
}
The callback convention is: cb(error, results...)
b) Use promises
DatabaseAccess.prototype.getWordPool = function () {
return RoundWord.find({}, 'words decoys', function (err, results) {
if (err) {
throw err; // however you might want to sanitize it
}
return results;
});
}
To consume this result you will need to do it as a promise
databaseAccess.getWordPool()
.catch(function (err) {
// process the error here
})
.then(function (results) {
// something with results
});
It will work if you change to this:
var dbAccess = require('../dao/dbAccess');
dbaInstance = new dbAccess();
dbaInstance.getWordPool(function(wordPool){console.log (wordPool);});
And:
var DatabaseAccess = function() {}
DatabaseAccess.prototype.getWordPool = function (cb) {
RoundWord.find({},'words decoys', function(err, wordPoolFromDB) {
if (err) throw err;
//console.log(wordPoolFromDB); -working ok
cb(wordPoolFromDB);
});
}
module.exports = DatabaseAccess;
If the function is Asynchronous you need to pass a callback to find to get the result:
DatabaseAccess.prototype.getWordPool = function (callback) {
RoundWord.find({},'words decoys', function(err, wordPoolFromDB) {
if (err) throw err;
callback(err, wordPoolFromDB);
});
}
and call it as follows in main:
dbaInstance.getWordPool(function (err, wordPool) {
console.log (wordPool);
// wordPool is only available inside this scope,
//unless assigned to another external variable
});
// cannot access wordPool here
function get (id, ignore) {
var deferred = $q.defer();
$http.get('v1/info/' + id, {
ignoreAuthModule: ignore
})
.success(function (data) {
deferred.resolve(data.data);
})
.error(function (reason) {
deferred.reject(reason.message););
});
return deferred.promise;
}
init();
function init(){
users.get($routeParams.id)
.then(function (data) {
if(data.has_something === 1){
$scope.hasSomething = true;
}else{
$scope.hasSomething = false;
}
});
}
I have a Service that get the information about user using promise and Fetching information from the service with init function
//if i call init function this should call two times one from function initialization and other i'm calling it from service
how can i stop two times calling api I mean it should call one time if already called
You're using the explicit promise creation antipattern here, and your code could be much simpler. Here is how you can use memoization to avoid requesting the same user twice:
.factory('users', ['$http', function ($http) {
var userPromises = {};
function get (id, ignore) {
if (!userPromises[id]) {
userPromises[id] = $http.get('v1/info/' + id, {
ignoreAuthModule: ignore
})
.then(function (data) {
return data.data;
})
.catch(function (reason) {
throw new Error(reason.message);
});
}
return userPromises[id];
}
return {
get: get
};
});
You can assign your deferred.promise to some variable and then return that variable, and before your http call just check whether that variable is already defined or not
function get (id, ignore) {
if (angular.isUndefined(user)) {
var deferred = $q.defer();
$http.get('v1/info/' + id, {
ignoreAuthModule: ignore
}).then(function(response) {
if (response.status == 200) {
deferred.resolve(response.data);
} else {
deferred.reject(response.data);
};
user = deferred.promise;
return user;
} else {
return user;
}
}
This way your api will get called only once.
I would like to make http call synchronously using Q Promises, I have 100 students that I need for each of them to take some data from another platform and to do that I was trying via Q Promises but it does not seem like it is doing synchronously.
How do I make sure that another call is not being made once one is finished with parsing it's response and insertion into mongodb:
my code so far looks like this:
var startDate = new Date("February 20, 2016 00:00:00"); //Start from February
var from = new Date(startDate).getTime() / 1000;
startDate.setDate(startDate.getDate() + 30);
var to = new Date(startDate).getTime() / 1000;
iterateThruAllStudents(from, to);
function iterateThruAllStudents(from, to) {
Student.find({status: 'student'})
.populate('user')
.exec(function (err, students) {
if (err) {
throw err;
}
async.eachSeries(students, function iteratee(student, callback) {
if (student.worksnap.user != null) {
var worksnapOptions = {
hostname: 'worksnaps.com',
path: '/api/projects/' + project_id + '/time_entries.xml?user_ids=' + student.worksnap.user.user_id + '&from_timestamp=' + from + '&to_timestamp=' + to,
headers: {
'Authorization': 'Basic xxxx='
},
method: 'GET'
};
promisedRequest(worksnapOptions)
.then(function (response) { //callback invoked on deferred.resolve
parser.parseString(response, function (err, results) {
var json_string = JSON.stringify(results.time_entries);
var timeEntries = JSON.parse(json_string);
_.forEach(timeEntries, function (timeEntry) {
_.forEach(timeEntry, function (item) {
saveTimeEntry(item);
});
});
});
callback();
}, function (newsError) { //callback invoked on deferred.reject
console.log(newsError);
});
}
});
function saveTimeEntry(item) {
Student.findOne({
'worksnap.user.user_id': item.user_id[0]
})
.populate('user')
.exec(function (err, student) {
if (err) {
throw err;
}
student.timeEntries.push(item);
student.save(function (err) {
if (err) {
console.log(err);
} else {
console.log('item inserted...');
}
});
});
}
function promisedRequest(requestOptions) {
//create a deferred object from Q
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
var deferred = Q.defer();
var req = http.request(requestOptions, function (response) {
//set the response encoding to parse json string
response.setEncoding('utf8');
var responseData = '';
//append data to responseData variable on the 'data' event emission
response.on('data', function (data) {
responseData += data;
});
//listen to the 'end' event
response.on('end', function () {
//resolve the deferred object with the response
console.log('http call finished');
deferred.resolve(responseData);
});
});
//listen to the 'error' event
req.on('error', function (err) {
//if an error occurs reject the deferred
deferred.reject(err);
});
req.end();
//we are returning a promise object
//if we returned the deferred object
//deferred object reject and resolve could potentially be modified
//violating the expected behavior of this function
return deferred.promise;
}
Anyone could tell me what do I need to do to achieve such things?
Is it also possible so that I know when all of the http calls are finished and the insertion is done for all...
I would abandon your current approach and use the npm module request-promise.
https://www.npmjs.com/package/request-promise
It's very popular and mature.
rp('http://your/url1').then(function (response1) {
// response1 access here
return rp('http://your/url2')
}).then(function (response2) {
// response2 access here
return rp('http://your/url3')
}).then(function (response3) {
// response3 access here
}).catch(function (err) {
});
Now you just need to convert this to some kind of iteration for the 100 requests you want and the job will be done.
I'm doing this login exercise where users can login and post notes, and view the notes that they've posted. My problem is when I logout and login with a different user I see the notes from the previous user.
Here's an illustration:
I log in with a different user then this shows up:
I restart the page and the appropriate note shows up:
The controller for this:
exports.homeController = function ($scope, $location, $q, $users, $window, $notes, $http) {
var auth = function () {
var userInfo = $users.getUserInfo()
if (userInfo) {
return $q.when(userInfo)
} else {
return $q.reject({ authenticated: false })
}
}
$scope.userInfo = auth()
myNotes($scope.userInfo.$$state.value.accessToken) // I invoke my function to get the notes for each specific user but it doesn't seem to work.
$scope.logout = function () {
$users.logout()
.then(function (results) {
$scope.userInfo = null
$scope.myNotes = null
$location.path('/')
}, function (err) {
console.log(err)
})
}
$scope.notes = {
notes: ''
}
$scope.postNote = function () {
$notes.postNotes($scope.userInfo.$$state.value.accessToken, $scope.notes)
.then(function (result) {
$scope.myNotes.push($scope.notes)
$scope.notes = ''
}, function (err) {
console.log(err)
})
}
function myNotes (user_id) {
$notes.getMyNotes(user_id)
.then(function (result) {
console.log(result)
$scope.myNotes = result.data
}, function (err) {
console.log(err)
})
}
}
This is the app https://login-sys.herokuapp.com/
I've found your non-minified code for the services.
Based on that I think the problem is that you declare var deferred = $q.defer() one time in the $notes service.
I think it should be "renewed" every time the service methods are called:
function getMyNotes (user_id) {
var deferred = $q.defer();
$http.get('/api/myNotes/' + user_id + '?access_token=' + user_id)
.then(function (result) {
deferred.resolve(result)
}, function (err) {
deferred.reject(err)
});
return deferred.promise
}
Similarly in postNotes.
The second time you return the same promise with the same value, so your homeController's getMyNotes function will get the same result despite the $notes service making a new request.
In the $users service's logout and signup functions you are already using it correctly.
In "view" method within my controller was previously using node-async but I wanted to try out using q.
I'm currently trying to convert this
exports.view = function (req, res) {
var category = req.params.category,
id = req.params.id,
ip = req.connection.remoteAddress,
slug = req.params.slug,
submission,
userId = typeof req.session.user !== 'undefined' && req.session.user.id ? req.session.user.id : null,
views;
var getSubmission = function (submissionId, callback) {
Submission.getSubmission({
id: submissionId
}, function (err, submission) {
if (err) {
callback(err);
} else if (submission) {
callback(null, submission);
} else {
callback(err);
}
});
};
async.waterfall([
function (callback) {
getSubmission(id, callback);
},
function (submission, callback) {
res.render('submission', {
title: submission.title + ' -',
submission: submission
});
}]);
To using q... I started doing something like:
var getSubmission = function(id) {
return Submission.getSubmission({
id : submissionId
}).then(function(submission) {
return submission;
});
};
q.fcall(getSubmission).then(function(submission) {
console.log(submission);
});
But it's not quite working as I intended. Am I doing something wrong here? How can I do this?
Is Submission.getSubmission a call to a database? Then you can't "chain" promises to that. You'll have to use the deferred method:
var getSubmission = function(id) {
var deferred = Q.defer();
Submission.getSubmission({
id: id
}, function(err, data){
if (err) {
deferred.reject(err);
} else {
deferred.resolve(data);
}
});
return deferred.promise;
}
getSubmission(some_id).then(successCallback, failureCallback);
You can also use Q#denodeify to convert a function using nodejs-style callbacks (function(err, data)) into a promise based function. Thus, the above can also be achieved by the following:
getSubmissionPromise = Q.denodeify(Submission.getSubmission);
getSubmissionPromise({id: some_id}).then(successCallback, failureCallback);