Merge pull request #127 from Thorium/master

Allow override for custom ETag creation

Author: filipw

src/WebAPI.OutputCache/CacheOutputAttribute.cs

@@ -178,23 +178,26 @@ public override void OnActionExecuted(HttpActionExecutedContext actionExecutedCo
 
                 if (!string.IsNullOrWhiteSpace(cachekey) && !(WebApiCache.Contains(cachekey)))
                 {
-                    SetEtag(actionExecutedContext.Response, Guid.NewGuid().ToString());
+                    var response = actionExecutedContext.Response;
+                    var actionContext = actionExecutedContext.ActionContext;
+                    SetEtag(response, CreateEtag(actionExecutedContext, cachekey, cacheTime));
 
-                    if (actionExecutedContext.Response.Content != null)
+                    
+                    if (response.Content != null)
                     {
-                        actionExecutedContext.Response.Content.ReadAsByteArrayAsync().ContinueWith(t =>
+                        response.Content.ReadAsByteArrayAsync().ContinueWith(t =>
                             {
-                                var baseKey = config.MakeBaseCachekey(actionExecutedContext.ActionContext.ControllerContext.ControllerDescriptor.ControllerName, actionExecutedContext.ActionContext.ActionDescriptor.ActionName);
+                                var baseKey = config.MakeBaseCachekey(actionContext.ControllerContext.ControllerDescriptor.ControllerName, actionContext.ActionDescriptor.ActionName);
 
                                 WebApiCache.Add(baseKey, string.Empty, cacheTime.AbsoluteExpiration);
                                 WebApiCache.Add(cachekey, t.Result, cacheTime.AbsoluteExpiration, baseKey);
 
                                 WebApiCache.Add(cachekey + Constants.ContentTypeKey,
-                                                actionExecutedContext.Response.Content.Headers.ContentType.MediaType,
+                                                response.Content.Headers.ContentType.MediaType,
                                                 cacheTime.AbsoluteExpiration, baseKey);
 
                                 WebApiCache.Add(cachekey + Constants.EtagKey,
-                                                actionExecutedContext.Response.Headers.ETag.Tag,
+                                                response.Headers.ETag.Tag,
                                                 cacheTime.AbsoluteExpiration, baseKey);
                             });
                     }
@@ -204,6 +207,11 @@ public override void OnActionExecuted(HttpActionExecutedContext actionExecutedCo
             ApplyCacheHeaders(actionExecutedContext.ActionContext.Response, cacheTime);
         }
 
+        protected virtual string CreateEtag(HttpActionExecutedContext actionExecutedContext, string cachekey, CacheTime cacheTime)
+        {
+            return Guid.NewGuid().ToString();
+        }
+
         private void ApplyCacheHeaders(HttpResponseMessage response, CacheTime cacheTime)
         {
             if (cacheTime.ClientTimeSpan > TimeSpan.Zero || MustRevalidate || Private)

src/WebApi.OutputCache.V2/CacheOutputAttribute.cs

@@ -191,17 +191,19 @@ private async Task OnActionExecuted(HttpActionExecutedContext actionExecutedCont
 
                 if (!string.IsNullOrWhiteSpace(cachekey) && !(_webApiCache.Contains(cachekey)))
                 {
-                    SetEtag(actionExecutedContext.Response, Guid.NewGuid().ToString());
+                    SetEtag(actionExecutedContext.Response, CreateEtag(actionExecutedContext, cachekey, cacheTime));
 
-                    if (actionExecutedContext.Response.Content != null)
+                    var responseContent = actionExecutedContext.Response.Content;
+
+                    if (responseContent != null)
                     {
                         var baseKey = config.MakeBaseCachekey(actionExecutedContext.ActionContext.ControllerContext.ControllerDescriptor.ControllerName, actionExecutedContext.ActionContext.ActionDescriptor.ActionName);
-                        var contentType = actionExecutedContext.Response.Content.Headers.ContentType;
+                        var contentType = responseContent.Headers.ContentType;
                         string etag = actionExecutedContext.Response.Headers.ETag.Tag;
                         //ConfigureAwait false to avoid deadlocks
-                        var content = await actionExecutedContext.Response.Content.ReadAsByteArrayAsync().ConfigureAwait(false);
-                        
-                        actionExecutedContext.Response.Content.Headers.Remove("Content-Length");
+                        var content = await responseContent.ReadAsByteArrayAsync().ConfigureAwait(false);
+
+                        responseContent.Headers.Remove("Content-Length");
 
                         _webApiCache.Add(baseKey, string.Empty, cacheTime.AbsoluteExpiration);
                         _webApiCache.Add(cachekey, content, cacheTime.AbsoluteExpiration, baseKey);
@@ -242,6 +244,11 @@ protected virtual void ApplyCacheHeaders(HttpResponseMessage response, CacheTime
             }
         }
 
+        protected virtual string CreateEtag(HttpActionExecutedContext actionExecutedContext, string cachekey, CacheTime cacheTime)
+        {
+            return Guid.NewGuid().ToString();
+        }
+
         private static void SetEtag(HttpResponseMessage message, string etag)
         {
             if (etag != null)