Question

将缓存添加到我的应用程序一切正常，从缓存数据，使其过期并重新缓存。当我实现了将相同的过期数据再次放入缓存中的功能时，如果没有连接，我收到此错误：Cannot read property 'then' of undefined

以下是我的控制器的代码：

.controller('ItemsCtrl', function($scope, $http, DSCacheFactory) {

    //handle the catche to hold the items lits.
    self.itemsCache = DSCacheFactory.get("itemsCache");
    /*
    *Fcuntion to re-refresh the cach after expire
    *re-use the old cache if no internet connection available
    */
    self.itemsCache.setOptions({
        onExpire: function(key, value){
            getItems()
                .then(function(){
                console.log("Items Cache was automatically refreshed", new Date());
            }, function(){
                console.log("Errorgetting data put expired item back in the cache", new Date());
            });
        }
    });

    function getItems(){
        var cacheKey = "items",
            itemsData = self.itemsCache.get(cacheKey);
        if(itemsData){
            // if data in the cache dont make  HTTP calls.
            console.log("Found Data in cache", itemsData);
            //recive Data from the cache
            $scope.items = itemsData;
        }
        else{//if no data in the catch make HTTP calls.
            //HTTP request to get the items data.
            $http.get('services/data.json')
             .success(function(data){
                console.log("Recived data via HTTP");
                //caching the data recived from the http calls.
                self.itemsCache.put(cacheKey, data);
                $scope.items = data;
            });
        }//end of the else statment
    }
    getItems();
})

Answer 1

函数getItems没有返回任何东西 - 看起来你想要返回一个promise，所以它应该是下面的东西。

当您在缓存中找到该项时，您可以使用$ q.when创建一个在参数不是承诺时已经解决的承诺。

当您找不到它时，您可以从$ http.get返回链式承诺。

.controller('ItemsCtrl', function($scope, $http, DSCacheFactory, $q) {

    //handle the catche to hold the items lits.
    self.itemsCache = DSCacheFactory.get("itemsCache");
    /*
    *Fcuntion to re-refresh the cach after expire
    *re-use the old cache if no internet connection available
    */
    self.itemsCache.setOptions({
        onExpire: function(key, value){
            getItems()
                .then(function(itemsData){
                console.log("Items Cache was automatically refreshed", new Date());
            }, function(){
                console.log("Errorgetting data put expired item back in the cache", new Date());
            });
        }
    });

    function getItems(){
        var cacheKey = "items",
            itemsData = self.itemsCache.get(cacheKey);
        if(itemsData){
            // if data in the cache dont make  HTTP calls.
            console.log("Found Data in cache", itemsData);
            //recive Data from the cache
            $scope.items = itemsData;
            return $q.when(itemsData);
        }
        else{//if no data in the catch make HTTP calls.
            //HTTP request to get the items data.
            return $http.get('services/data.json')
             .success(function(data){
                console.log("Recived data via HTTP");
                //caching the data recived from the http calls.
                self.itemsCache.put(cacheKey, data);
                $scope.items = data;
                return data;
            });
        }//end of the else statment
    }
    getItems();
})

Answer 2

这不起作用我只是不想破坏这个问题。

.controller('ItemsCtrl', function($scope, $http, $q, DSCacheFactory) {

        //handle the catche to hold the items lits.
        self.itemsCache = DSCacheFactory.get("itemsCache");
        /*
        *Fcuntion to re-refresh the cach after expire
        *re-use the old cache if no internet connection available
        */
        self.itemsCache.setOptions({
            onExpire: function(key, value){
                getItems()
                    .then(function(){
                    console.log("Items Cache was automatically refreshed", new Date());
                }, function(){
                    console.log("Errorgetting data put expired item back in the cache", new Date());
                });
            }
        });

        function getItems(){
            var deferred = $q.defer(),
                cacheKey = "items",
                itemsData = self.itemsCache.get(cacheKey);

            if(itemsData){
                // if data in the cache dont make  HTTP calls.
                console.log("Found Data in cache", itemsData);
                //recive Data from the cache
                $scope.items = itemsData;
                deferred.resolve(itemsData);
            }
            else{//if no data in the catch make HTTP calls.
                //HTTP request to get the items data.
                $http.get('services/data.json')
                 .success(function(data){
                    console.log("Recived data via HTTP");
                    //caching the data recived from the http calls.
                    self.itemsCache.put(cacheKey, data);
                    $scope.items = data;
                    deferred.resolve(data);
                });
            }//end of the else statment
        }
        getItems();
    })

angularJS / ionic无法读取属性＆＃39;然后＆＃39;未定义的

2 个答案: