How to get data by service and $cacheFactory by one method - angularjs

Question

I have a factory which get data from server. In the factory method I have used $cacheFactory to cache getting data. My code is as follows..
var buyersService = function ($http, $q,$cacheFactory) {
var serviceBase = '/api/OMData/';
var BuyersFactory = {};
buyersService.cache = $cacheFactory('cacheId');
BuyersFactory.GetBuyers = function () {
var dataList = buyersService.cache.get('BuyerData');
if (dataList != null && dataList.length > 0) {
return dataList;
}
else {
return $http.get(serviceBase + 'GetBuyers').then(
function (results) {
buyersService.cache.put("BuyerData", results.data);
return results.data;
});
}
}
app.factory('OMDataService', ['$http', '$q', '$cacheFactory', buyersService]);
});
Now I have called GetBuyers method from controller. My method is like below..
var BuyerController = function ($scope, BuyersService) {
$scope.Buyers = [];
init();
function init() {
getBuyers();
}
function getBuyers() {
BuyersService.GetBuyers()
.then(function (data) {
$scope.Buyers = data;
}, function (error) {
alert(error.message);
});
}
};
app.register.controller('BuyersController', ['$scope', 'OMDataService', BuyerController]);
When I have executed my controller method second time I have got an error message in promise part.
Object doesn't support property or method 'then'

Answer 1

The issue here is that your function returns two different things: either a promise or plain data. To remedy this, use another promise to control the flow and return that one as the result of the function.
Update your code to
var buyersService = function ($http, $q,$cacheFactory) {
var serviceBase = '/api/OMData/';
var BuyersFactory = {};
buyersService.cache = $cacheFactory('cacheId');
BuyersFactory.GetBuyers = function () {
var buyersDataIsAvailable = $q.defer();
var dataList = buyersService.cache.get('BuyerData');
if (dataList != null && dataList.length > 0) {
buyersDataIsAvailable.resolve(dataList);
}
else {
$http.get(serviceBase + 'GetBuyers').then(
function (results) {
buyersService.cache.put("BuyerData", results.data);
buyersDataIsAvailable.resolve(results.data);
});
}
return buyersDataIsAvailable.promise;
}
app.factory('OMDataService', ['$http', '$q', '$cacheFactory', buyersService]);
});