Angular response objects and storing the data - angularjs

Question

I'm trying to take the response of an $http request and save it to a custom cache. I want to then use that cache to display data into the view. I thought the cache would be checked automatically on each request before fetching new data, but that doesn't seem to be working for me.
The problem I'm having is I can't seem to save the data. The following function needs to make 2 requests: articles and images.
getImages: function() {
var cache = $cacheFactory('articlesCache');
$http.get(posts)
.then(function (data) {
var articles = data;
angular.forEach(articles, function (article) {
var imageId = {id: article.image_id};
$http.post(images, imageId)
.then(function (response) {
article.image = response;
cache.put(article.url, article);
});
});
});
return cache;
}
This creates the custom cache, but there's no data in the returned object. I know now that I can't save the data this way, but I don't know why or how I would go about doing it.
Can anyone explain how storing response data works? Where, if at all, does using promises come in here?

Answer 1

Your return statement executes before the code in your then function does. If you want to return the cache you'll want to run everything through the $q service and then return the resolved promise.
This is probably not the best way to use $cacheFactory. Typically you'd expose your cache as a service at a higher level and then access the cache via the service where needed.
So on your main module you'd have something like this to create the cache.
.factory('cache', function ($cacheFactory) {
var results = $cacheFactory('articleCache');
return results;
})
Then where ever you need the cache you inject it into the controller and use cache.get to retrieve the data from it.
If you want to use $q to implement this, your code would look something like the code below. (Disclaimer: I've never used $q with $cacheFactory like this, so without all of your components, I can't really test it, but this should be close.)
var imageService = function ($http, $q,$cacheFactory) {
var imageFactory = {};
imageService.cache = $cacheFactory('articlesCache');
imageFactory.getImages = function () {
var images = $q.defer();
$http.get(posts)
.then(function (data) {
var articles = data;
angular.forEach(articles, function (article) {
var imageId = {id: article.image_id};
$http.post(images, imageId)
.then(function (response) {
article.image = response;
cache.put(article.url, article);
});
images.resolve(cache.get('articlesCache'))
});
});
return images.promise
app.factory('ImageService', ['$http', '$q', '$cacheFactory', imageService]);
});
I adapted the code from this answer: How to get data by service and $cacheFactory by one method
That answer is just doing a straight $http.get though. If I understand what you're doing, you already have the data, you are posting it to your server and you want to avoid making get call to retrieve the list, since you have it locally.