Question

我创建了一个UserService，如下所示：

angular.module('nrApp').factory('userService', ['Restangular', 'UserModel', 'DSCacheFactory', function (Restangular, UserModel, DSCacheFactory) {
    // Create a new cache called "profileCache"
    var userCache = DSCacheFactory('userCache', {
        maxAge: 3600000,
        deleteOnExpire: 'aggressive',
        storageMode: 'localStorage', // This cache will sync itself with `localStorage`.
        onExpire: function (key, value) {
            Restangular.oneUrl('users', key).get().then(function(data) {
                userCache.put(key, data);
            });
        }
    });

    Restangular.extendModel('users', function(obj) {
        return UserModel.mixInto(obj);
    });

    Restangular.addRequestInterceptor(function(element, operation, what, url) {
        if(operation === 'get') {
            debugger;
            //Check the cache to see if the resource is already cached
            var data = userCache.get(url);
            //If cache object does exist, return it
            if(data !== undefined) {
                angular.extend(element, data);
            }

            return element;
        }
    });

    Restangular.addResponseInterceptor(function(data, operation, what, url, response) {
        //Cache the response from a get method
        if(operation === 'get') {
            debugger;
            userCache.put(url, data);
        }

        //Unvalidate the cache when a 'put', 'post' and 'delete' is performed to update the cached version.
        if (operation === 'put' || operation === 'post' || operation === 'delete') {
            userCache.destroy();
        }

        return response;
    });

    return Restangular.service('users');
}]);

从评论可以看出，我想要实现的是每当使用Restangular通过此服务执行Get请求时，都会检查本地缓存，如果缓存返回一个对象，则它会扩展到restangular元素。想要实现的流程是在为该请求找到缓存对象时取消对服务器的请求。

然而，没有任何运气，即使在缓存中找到了对象，addResponseInterceptor方法仍会执行。

是否有任何可能的解决方案在“获取”期间取消对服务器的请求？请求？

谢谢！：）

Answer 1

一种方法是通过httpConfig取消它。 Restangular为您提供httpConfig对象作为addFullRequestInterceptor方法中的参数。您可以使用以下内容：

RestangularProvider.addFullRequestInterceptor(function(element, operation, what, url, headers, params, httpConfig ) {
    ...
    if found in cache {
        var defer = $q.defer();
        httpConfig.timeOut = defer.promise;
        defer.resolve();
    }
    ...
}

希望这有帮助。

Answer 2

通过简单地更改RequestInterceptor中的httpConfig设置，我解决了通过角度缓存CacheFactory实例返回缓存数据的特定问题。示例如下所示：

angular.module('App')
.factory('Countries', function (Restangular, CacheFactory, $q) {

    var countryCache;
    var countryService;

    // Check to make sure the cache doesn't already exist
    if (!CacheFactory.get('countryCache')) {
        countryCache = CacheFactory('countryCache', { maxAge: 60 * 60 * 1000 });
    }

    if (!countryService) {
        countryService = Restangular.service('countries');

    Restangular.addFullRequestInterceptor(function(element, operation, what, url, headers, params, httpConfig) {

            if (what === 'countries') {
                switch (operation) {
                    case 'getList':
                        httpConfig.cache = countryCache;
                        break;

                    default:
                        break;
                }               
            }

            return { 
                element: element,
                headers: headers,
                params: params,
                httpConfig: httpConfig
            };

        });

    }

    return countryService;
});

Answer 3

您可以修饰$ http以防止多个请求到同一个网址。 Restangular使用$ http，不需要添加fullRequestIntercepter来取消请求，因为这会在发送之前阻止请求。

    $provide.decorator('$http', function ($delegate, $cacheFactory, $rootScope) {
    var $http = $delegate;
    var customCache = $cacheFactory('customCache');
    var wrapper = function () {
        var key = arguments[0].url;
        var requestPromise = customCache.get(key);
        if (!requestPromise){
            $rootScope.requestCount++;
            requestPromise = $http.apply($http, arguments);
            requestPromise.then(function(){
                customCache.remove(key);
            });
            customCache.put(key, requestPromise)
        }
        return requestPromise;
    };

    Object.keys($http).filter(function (key) {
        return (typeof $http[key] === 'function');
    }).forEach(function (key) {
        wrapper[key] = function () {
            return $http[key].apply($http, arguments);
        };
    });

    return wrapper;
});

Example here

使用Restangular取消对服务器的GET请求

3 个答案: