I'm trying to do a caching factory for http requests, so it doesn't make the server do a lot of work for the same request. But It seems my way of using deferred "swallows" the data, and I don't know why.
Console output for below:
data fetched:
Object {state: "OK", data: Object, errorMessage: null, exception: null}
success
undefined
ImportFactory:
factory("importFactory", function ($http, $q, loggingService) {
return{
fetchedData: [],
cacheTransport: function (transportsId, data) {
this.fetchedData.push({"transportsId": transportsId, "data": data});
},
getImport: function (transportsId) {
var factory = this;
var deferred = $q.defer();
var preFetchedTransport = this.findTransport(transportsId);
if (preFetchedTransport === null) {
console.log('fetching from backend');
return $http.post("/import/create/" + transportsId).then(function (data) {
console.log('data fetched:');
console.log(data);
factory.cacheTransport(transportsId, data);
deferred.resolve(data);
});
}
preFetchedTransport = deferred.promise;
return preFetchedTransport;
},
findTransport: function (transportsId) {
for (var i = 0; i < this.fetchedData.length; i++) {
var transportObj = this.fetchedData[i];
if (transportObj.transportsId === transportsId) {
return transportObj.data;
}
}
return null;
}
};
});
Controller
.controller('ImportController', function ($scope, $routeParams, importFactory){
$scope.transportId = $routeParams.id;
importFactory.getImport($scope.transportId).then(function (successData) {
console.log('success');
console.log(successData);
}, function (errorData) {
console.log('error');
console.log(errorData);
});
You basically need this: Demo here.
var cachedPromises = {};
return {
getStuff: function(id) {
if (!cachedPromises[id]) {
cachedPromises[id] = $http.post("/import/create/" + id).then(function(resp) {
return resp.data;
});
}
return cachedPromises[id];
}
};
Now, when you fetch that data, you can manipulate and it will be changed when you access it in the future.
myService.getStuff(whatever).then(function(data) {
data.foo = 'abc';
});
//elsewhere
myService.getStuff(whatever).then(function(data) {
console.log(data.foo); // 'abc'
});
Here's a demo that does this, as well as a view updating trick (bind the object to the view before the data comes in), and an idea of how you could change the data separately from the cache, in case you want to have the original data and the changing data. http://jsbin.com/notawo/2/edit
Remember to avoid that nasty promise anti-pattern. If you already have a promise, use that instead of creating another with $q. $http already returns a promise and that promise is sufficient for whatever you need if you use it properly.
just change the loop condition look like this and then test i think your function and defer is work fine but the loop does not sent the correct data
for(var i = 0; i < this.fetchedData.length; i++) {
if (this.fetchedData[i].transportsId === transportsId) {
return this.fetchedData[i].data;
}
}
return null;
}
The reason you are getting undefined is you are not returning anything from the $http.post().then() !
Also in your getImport() function you are returning an empty promise when the transport is already cached. You need to resolve it to your already cached transport object.
getImport: function (transportsId) {
var factory = this;
var deferred = $q.defer();
var preFetchedTransport = this.findTransport(transportsId);
if (preFetchedTransport === null) {
console.log('fetching from backend');
return $http.post("/import/create/" + transportsId).then(function (data) {
console.log('data fetched:');
console.log(data);
factory.cacheTransport(transportsId, data);
return data; //this was missing
});
}
// resolve it with transport object if cached
deferred.resolve(preFetchedTransport);
return deferred.promise;
},
Related
UPDATE:
I decided that using the JS Module Pattern was not "keeping it simple", so I scrapped it and used jQuery's deferred object to return the data I was looking for. What I really needed was to simply load a JSON file and populate an object. I was just trying to be too fancy by incorporating the JS Module Pattern.
Many thanks to #kiramishima for the correct answer.
Below is the finished code:
function getData(){
var url = CONTEXT + "/json/myJsonFile.json";
return $.getJSON(url);
}
getData()
.done(function(data){
myGlobalObj = data;
})
.fail(function(data){
console.log("fetching JSON file failed");
});
I think I'm getting a little too fancy for my own good here. I'm loading a JSON file and trying to return the API via JS module pattern. Problem is that I believe I'm not implementing the promise correctly and I don't know how to fix it.
Here's my JSON:
{
"result": {
"one": {
"first_key":"adda",
"second_key":"beeb",
"third_key":"cffc"
},
"two": {
"first_key":"adda",
"second_key":"beeb",
"third_key":"cffc"
}
}
}
And here's my JS Module implementation:
var data = (function() {
var url = "/json/dummy.json";
var getAllData = function() {
return $.getJSON(url, function(result){});
};
var promise = getAllData(); // the promise
return {
getFirstObjSecondKey:function() {
return promise.success(function(data) {
return data.result.one.second_key;
});
},
getSecondObjThirdKey:function() {
return promise.success(function(data) {
return data.result.two.third_key;
});
},
};
})();
The problem is that "getAllData()" is coming back as undefined and I'm not sure why; that method returns a Promise that I should be able to handle in the "done" function. How far off am I?
Thanks for any helpful input. This is the first time I'm messing with the JS Module Pattern.
I dont know what is your problem, but I test with:
var getAllData = function() {
return $.getJSON('/json/dummy.json', function(result){})
}
getAllData().done(function(data){ console.log(data.result.one.second_key) }) // prints beeb
works fine in that case, but if try this:
var data = (function() {
var url = '/json/dummy.json';
var getAllData = function() {
return $.getJSON(url, function(result){});
};
return {
getFirstObjSecondKey:function() {
getAllData().done(function(data) {
return data.login;
});
},
getSecondObjThirdKey:function() {
getAllData().done(function(data) {
return data.name;
});
},
};
})();
data.getFirstObjSecondKey returns undefined, then can u pass anonymous function:
var data = (function() {
var url = '/json/dummy.json';
var getAllData = function() {
return $.getJSON(url, function(result){});
};
return {
getFirstObjSecondKey:function(callback) {
getAllData().done(function(data) {
callback(data.result.one.second_key);
});
},
getSecondObjThirdKey:function(callback) {
getAllData().done(function(data) {
callback(data.result.two.third_key);
});
},
};
})();
var t;
data.getFirstObjSecondKey(function(data){
//data should contain the object fetched by getJSON
console.log(data); // prints beeb
t = data; // assign t
})
console.log(t) // prints beeb
Other solution, return always the deferred object
kiramishima's answer works, but it mixes callbacks with Promises. If you're using promises, you should try not to mix both styles.
You have to return a Promise from your functions. Remember that promises can be chained, that is, if you return a Promise from the done function, that becomes the new Promise
var data = (function() {
var url = "/json/dummy.json";
var getAllData = function() {
return $.getJSON(url, function(result){});
};
return {
getFirstObjSecondKey:function() {
return getAllData().done(function(data) {
return new Promise(function(resolve, reject){
resolve(data.result.one.second_key);
});
});
},
getSecondObjThirdKey:function() {
return getAllData().done(function(data) {
return new Promise(function(resolve, reject){
resolve(data.result.one.third_key);
});
});
},
};
})();
data.getFirstObjSecondKey().done(function(secondKey) {
console.log('Second key', secondKey);
});
I want to populate some values in Json that are being calculated with angular-promises and these value should be updated after certain events.
I tried to call the factory which yields the values for example something like below and tried to call the functions GetWeeklyVal and GetDailyVal which are in charge of calculating the values :
this.salesList =
{"sales":[
{ "id":"A1", "dailyValue": GetDailyVal('A1'), "weeklyValue": GetWeeklyVal('A1')},
{ "id":"A2", "dailyValue": GetDailyVal('A2'), "weeklyValue": GetWeeklyVal('A2')}
]}
and in my controller I have:
$scope.sales= salesServices.salesList.sales;
but it didn't work. the values remain zero which is the default value in the application.
Why the values are not being updated and what would be a better solution?
update
This is the portion of the code I call the calculation functions: (I skip the portion to get the values based on passed id in here)
function GetDailyVal(id){
var dValue = 0;
salesService.getSales();
dValue = salesService.totalAmount;
return dValue;
}
this is the factory
.factory('salesService', ['$http', '$q'],
function salesInvoiceService($http, $q) {
var service = {
sales: [],
getSales: getSales,
totalAmount: 0
};
return service;
function getSales() {
var def = $q.defer();
var url = "http://fooAPI/salesinvoice/SalesInvoices"; //+ OrderDate filter
$http.get(url)
.success(function(data) {
service.sales = data.d.results;
setTotalAmount(service.sales);
def.resolve(service.sales);
})
.error(function(error){
def.reject("Failed to get sales");
})
.finally(function() {
return def.promise;
});
}
function setTotalAmount(sales){
var sum = 0;
sales.forEach(function (invoice){
sum += invoice.AmountDC;
});
service.totalAmount = sum;
}
})
I think there are some errors in your code.
I give some sample code here. I think this will help you.
This is a sample code in one of my application. Check it.
service.factory('Settings', ['$http','$q', function($http,$q) {
return {
AcademicYearDetails : function(Details) {
return $http.post('/api/academic-year-setting', Details)
.then(function(response) {
if (typeof response.data === 'object') {
return response.data;
} else {
return $q.reject(response.data);
}
}, function(response) {
return $q.reject(response.data);
});
},
newUser : function(details) {
return $http.post('/api/new-user', details);
}
}
}]);
The reason why its not working is:
dailyValue: GetDailyVal('A1')
Here, GetDailyVal makes an async ajax call to an api. For handling async requests, you have to return a promise as follows in your GetDailyVal function as follows:
function GetDailyVal() {
salesService.getSales().then(function(data) { //promise
dValue = salesService.totalAmount;
return dValue;
})
}
Same thing need to be done for weeklyValue.
I want to call a function in another one.
The function to be called returns true or false:
$scope.verifsubdir = function(dir, tocheck) {
$http({method: 'GET', url: '/checkIsSubdir/'+dir+'/'+tocheck})
.success(function(result) {
return result.data;
})
.error(function(result) {
console.log("checksubdir oops");
});
};
The function call in another function:
$scope.CopyFiles = function(destination) {
for(var i=0; i<$scope.list.length; i++) {
console.log($scope.verifsubdir($scope.list[i],destination));
};
}
But I always get undefined.
However, when I merge the two functions I get true or false:
$scope.CopyFiles=function(destination){
for(var i=0; i<$scope.list.length; i++){
$http({method: 'GET', url:
'/checkIsSubdir/'+$scope.list[i]+'/'+destination})
.success(function(result) {
console.log("checkdir "+result.data);
})
.error(function(data, status, headers, config) {
console.log("checksubdir oops");
});
}
};
I want them to be separated. How to fix this?
In the $http call returns a promise, your should do something like this:
$scope.verifsubdir($scope.list[i],destination).then(function(resp) {
console.log(resp);
// assuming the response returns a boolean
$scope.list[i].verified = resp
});
Using $http from Angular gives you a Promise back (you can read more about them in the documentation for $q), and won't make your function return any value on its own (this is why you get undefined).
Your first function will need to return the promise and then you would need to add additional .success(...) or .error(...) callbacks inside your CopyFiles function:
$scope.verifsubdir = function (dir, tocheck) {
// Simply add return in front of $http here.
return $http(...
};
$scope.CopyFiles = function (destination) {
for (var i = 0; i < $scope.list.length; i++) {
$scope.verifsubdir($scope.list[i], destination).success(function (result) {
console.log("checkdir " + result.data);
});
}
};
In this scenario the requirement is to get the data with an Http request if the data is not in a buffer. If it's in the buffer, use it from there without the Http request.
I tried the code below but it doesn't make much sense; if the data is in the buffer I don't know if I should return from the function doing nothing or return the deferred promise. Any thoughts?
var dataBuffer = null;
var getData = function() {
var deferred = $q.defer();
if (dataBuffer != null) { // this is the part I'm not convinced
deferred.resolve();
return;
}
$http.get('/some/url/')
.success(function(data) {
dataBuffer = data;
deferred.resolve();
})
.error(function(data) {
deferred.reject();
});
return deferred.promise;
};
Invoked in the following way:
var promise = getData();
promise.then (
function(response) {
dataBuffer = .... // dataBuffer contains data
}
);
There is a clean simple way to use promises when you're not sure which is the code you're executing is asynchronous or not and it's using $q.when
So the code can be:
var getData = function() {
return $q.when(dataBuffer ? dataBuffer: $http.get('/some/url'))
};
Then when calling getData you can use the same code you posted or just simply:
getData()
.then(function(response){//...
})
.catch(function(err){//..
});
Beware of the deferred antipattern. You can accomplish what you are trying to do very cleanly, like this:
var dataBuffer;
var getData = function() {
if (dataBuffer) {
// return a resolved promise for dataBuffer if it is already populated
return $q.when(dataBuffer);
}
$http.get('/some/url/')
.then(function (data) {
dataBuffer = data.data;
return dataBuffer;
});
};
getData().then(function (data) {
// data contains the data you want
})
.catch(function (error) {
// error occurred.
});
dataBuffer should not be accessed outside of your getData function. To make this perfectly clear, you can wrap them together in an IIFE, although this is optional:
var getData = (function () {
var dataBuffer;
return function() {
if (dataBuffer) {
// return a resolved promise for dataBuffer if it is already populated
return $q.when(dataBuffer);
}
$http.get('/some/url/')
.then(function (data) {
dataBuffer = data.data;
return dataBuffer;
});
};
})();
getData().then(..etc etc etc...);
As a final note, remember that you can use $http's built-in caching features, and not have to reinvent the wheel with your own buffers:
// much simpler, isn't it?
var getData = function() {
$http.get('/some/url/', { cache: true }) // enable caching
.then(function (data) { return data.data });
};
getData().then(...etc etc etc...);
Why dont you enable cache instead of handling the buffer manually.
$http.get('/some/url/',{ cache: true})
.success(function(data) {
deferred.resolve(data);
})
.error(function(data) {
deferred.reject();
});
Below is part of code from angularjs service. It may not a specific question to angular though.
The $http.get('/api/test/1').then ( ... returns promise and I like to process the data returned by the call back. I am getting error when accessing filter method.
Test.filter(data.Root);
TypeError: Object #<Object> has no method 'filter'
But, I could access the data variable in the same scope (previous line) though.
var testApp = angular.module('testApp.services', []);
testApp.factory('Test', function ($http, $rootScope) {
var Test = {};
var data = [];
Test.filter = function (d) {
ret = data.filter(function (el) {
return el.Pid == d.Id;
});
return ret;
};
Test.data = function () {
return data[1];
};
Test.start = function () {
Test.asyncData = $http.get('/api/test/1')
.then(function (response) {
data = response;
return Test.filter(data.Root);
}, function (response) {
Test.error = 'Can\'t get data';
data = 'Error: ' + response.data;
return data;
});
};
return Test;
});
I think your error is coming from:
ret = data.filter(...
The data variable, which you set to the response, doesn't have a filter method.
It is probably either not of the type you think it is, or you meant to call the filter method on something else.