Nice article. We use the first approach in our code.
I tried what you suggested (e.g. my new code is
app.factory('invoicesService', ['$http', '$q', function($http, $q) {
var metaData = null;
var getMetaData = function () {
var deferred = $q.defer();
if (angular.isObject(metaData))
deferred.resolve(metaData);
else {
$http.get('/api/invoices/metadata')
.success(function (data) {
metaData = data;
deferred.resolve(data);
})
.error(function (data, status, header, config) {
deferred.reject(status);
});
}
return deferred.promise;
};
but I still got hit of my API controller's method twice. I'm going to look into Viv's idea now.
>You need to return a promise even if you return the cached data.
>
>So define your deferred at the top of the code then to return the cached data:
>
>
>if (angular.isObject(metaData)) {
> deferred.resolve(metaData);
> return deferred.promise;
>}
>
>
>This way you get the same data back regardless of whether the data was returned from the AJAX call or from the cached data.
>
>You might want to read this:
>
http://weblog.west-wind.com/posts/2014/Oct/24/AngularJs-and-Promises-with-the-http-Service>
>which explains some of the mechanics behind this...
>
>+++ Rick ---
>>
>
>
>Define your $q.defer() before the first call then deferred.resolve(metaData); return deferred.promise() with the cached data and return the promise in the if block.
>
>+++ Rick ---
>
>>Hi everybody,
>>
>>I have two pages in the same form that need to access the same data.
>>
>>Each of the pages is controlled by its own controller and both have this code in the init:
>>
>>
>>invoicesService.getMetaData().then(function (data) {
>> $scope.invoicesMetaData = data;
>>
>> });
>>
>>So, I want to somehow adjust the service code to not invoke the method twice. Here is what I attempted to do but it's not working:
>>
>>
>>app.factory('invoicesService', ['$http', '$q', function($http, $q) {
>>
>> var metaData = null;
>>
>> var getMetaData = function () {
>> if (angular.isObject(metaData))
>> return metaData;
>>
>> var deferred = $q.defer();
>> $http.get('/api/invoices/metadata')
>> .success(function (data) {
>> metaData = data;
>> deferred.resolve(data);
>>
>> })
>> .error(function (data, status, header, config) {
>> deferred.reject(status);
>> });
>> return deferred.promise;
>> };
>>
>>I still get 2 hits in my API controller. Do you see how should I change the above to avoid the second call after the first one was already made?
>>
>>Thanks in advance.
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