Added the NoCacheLookupForPosts option.

This allows the developer to never use the previously cached value if the
incomming request is a POST. We are still caching the result for subsequent
requests (that are not POSTs). This is handy when a POST to an action is
generating a lot of computation and further GET requests would generate
the same result.

Author: moonpyk

DevTrends.MvcDonutCaching/DonutOutputCacheAttribute.cs

@@ -126,7 +126,17 @@ public override void OnActionExecuting(ActionExecutingContext filterContext)
             // Are we actually storing data on the server side ?
             if (_cacheSettings.IsServerCachingEnabled)
             {
-                var cachedItem = _outputCacheManager.GetItem(cacheKey);
+                CacheItem cachedItem = null;
+
+                // If the request is a POST, we lookup for NoCacheLookupForPosts option
+                // We are fetching the stored value only if the option has not been set and the request is not a POST
+                if (
+                    (_cacheSettings.Options & OutputCacheOptions.NoCacheLookupForPosts) != OutputCacheOptions.NoCacheLookupForPosts || 
+                    filterContext.HttpContext.Request.HttpMethod != "POST"
+                )
+                {
+                    cachedItem = _outputCacheManager.GetItem(cacheKey);
+                }
 
                 // We have a cached version on the server side
                 if (cachedItem != null)

DevTrends.MvcDonutCaching/OutputCacheOptions.cs

@@ -14,5 +14,10 @@ public enum OutputCacheOptions
         /// No matter what, never use the Post data to generate the cache key name
         /// </summary>
         IgnoreFormData = 0x2,
+        /// <summary>
+        /// If the request is a POST, don't lookup for a cached result, execute the the result normally, 
+        /// caching it for subsequent GET (or any other non POST verb).
+        /// </summary>
+        NoCacheLookupForPosts = 0x4,
     }
 }