feat($http): change $http to allow removing/replacing individual requests in $http cache

Adds $http.removeCache method.
Adds/implements replaceCache property in $http request configuration.

Closes angular#5968

Author: njs50

src/ng/http.js

@@ -338,6 +338,17 @@ function $HttpProvider() {
      * If you set the default cache to `false` then only requests that specify their own custom
      * cache object will be cached.
      *
+     * If you need to bypass and overwrite the cache you can set the `replaceCache` property to
+     * `true` in the request configuration.
+     *
+     * If you wish to purge stale data from the cache without making a request you can use the
+     * {@link ng.$http#methods_removeCache $http.removeCache} method and pass it the configuration
+     * object that was used to create the request you wish to purge.
+     * ```js
+     *    $http.removeCache({method: 'GET', url: '/someUrl'})
+     * ```
+     *
+     *
      * # Interceptors
      *
      * Before you start creating interceptors, be sure to understand the
@@ -551,6 +562,8 @@ function $HttpProvider() {
      *      GET request, otherwise if a cache instance built with
      *      {@link ng.$cacheFactory $cacheFactory}, this cache will be used for
      *      caching.
+     *    - **replaceCache** - `{boolean}` - If true this request will bypas the cache and  replace
+     *      any previously cached value.
      *    - **timeout** – `{number|Promise}` – timeout in milliseconds, or {@link ng.$q promise}
      *      that should abort the request when resolved.
      *    - **withCredentials** - `{boolean}` - whether to to set the `withCredentials` flag on the
@@ -871,6 +884,29 @@ function $HttpProvider() {
      */
     createShortMethodsWithData('post', 'put');
 
+    /**
+     * @ngdoc method
+     * @name $http#removeCache
+     *
+     * @description
+     * Removes a request from the cache without generating a new request.
+     *
+     * @param {Object} config configuration object (as per the request that created the cache entry)
+     */
+     $http.removeCache = function(config) {
+
+        var url = buildUrl(config.url, config.params);
+
+        var cache = isObject(config.cache) ? config.cache
+              : isObject(defaults.cache) ? defaults.cache
+              : defaultCache;
+
+        if (cache) {
+          cache.remove(url);
+        }
+
+     };
+
         /**
          * @ngdoc property
          * @name $http#defaults
@@ -937,7 +973,11 @@ function $HttpProvider() {
       }
 
       if (cache) {
-        cachedResp = cache.get(url);
+        if (config.replaceCache) {
+          cache.remove(url);
+        } else {
+          cachedResp = cache.get(url);
+        }
         if (isDefined(cachedResp)) {
           if (cachedResp.then) {
             // cached request has already been sent, but there is no response yet

test/ng/httpSpec.js

@@ -1138,6 +1138,24 @@ describe('$http', function() {
       });
 
 
+      it('should be able to clear the cache for a request', function() {
+        doFirstCacheRequest();
+
+        $http.removeCache({method: 'GET', url: '/url', cache: cache});
+
+        $httpBackend.expect('GET', '/url').respond();
+        $http({method: 'GET', url: '/url', cache: cache});
+      });
+
+
+      it('should be able to bypass and overwrite the cache for a request', function() {
+        doFirstCacheRequest();
+
+        $httpBackend.expect('GET', '/url').respond();
+        $http({method: 'GET', url: '/url', cache: cache, replaceCache: true});
+      });
+
+
       it('should always call callback asynchronously', function() {
         doFirstCacheRequest();
         $http({method: 'get', url: '/url', cache: cache}).then(callback);