Service retrieves data from datastore but does not update ui - html

Question

I have a service which retrieves data from the datastore (Web SQL). Afterwards, it stores the data in a AngularJS array. The problem is that this does not initiate changes to the UI.
Contrary, if after the retrieval of data from datastore, I call a web services using a $get method and append the results to the previous array, all data updates the UI.
Any suggestions? Is it possible that I fill the array before the Angular binds the variable?
Can I somehow delay the execution of the service?
Most of the code has been taken from the following example: http://vojtajina.github.io/WebApp-CodeLab/FinalProject/

Answer 1

In order for the UI to magically update, some changes must happen on properties of the $scope. For example, if retrieving some users from a rest resource, I might do something like this:
app.controller("UserCtrl", function($http) {
$http.get("users").success(function(data) {
$scope.users = data; // update $scope.users IN the callback
}
)
Though there is a better way to retrieve data before a template is loaded (via routes/ng-view):
app.config(function($routeProvider, userFactory) {
$routeProvider
.when("/users", {
templateUrl: "pages/user.html",
controller: "UserCtrl",
resolve: {
// users will be available on UserCtrl (inject it)
users: userFactory.getUsers() // returns a promise which must be resolved before $routeChangeSuccess
}
}
});
app.factory("userFactory", function($http, $q) {
var factory = {};
factory.getUsers = function() {
var delay = $q.defer(); // promise
$http.get("/users").success(function(data){
delay.resolve(data); // return an array of users as resolved object (parsed from JSON)
}).error(function() {
delay.reject("Unable to fetch users");
});
return delay.promise; // route will not succeed unless resolved
return factory;
});
app.controller("UserCtrl", function($http, users) { // resolved users injected
// nothing else needed, just use users it in your template - your good to go!
)
I have implemented both methods and the latter is far desirable for two reasons:
It doesn't load the page until the resource is resolved. This allows you to place a loading icon, etc, by attaching handlers on the $routeChangeStart and $routeChangeSuccess.
Furthermore, it plays better with 'enter' animations in that, all your items don't annoyingly play the enter animation every time the page is loaded (since $scope.users is pre populated as opposed to being updated in a callback once the page has loaded).

Answer 2

Assuming you're assigning the data to the array in the controller, set an $scope.$apply() after to have the UI update.
Ex:
$scope.portfolio = {};
$scope.getPortfolio = function() {
$.ajax({
url: 'http://website.com:1337/portfolio',
type:'GET',
success: function(data, textStatus, jqXHR) {
$scope.portfolio = data;
$scope.$apply();
},
error: function(jqXHR, textStatus, errorThrown) {
console.log(errorThrown);
}
});
};