ASP.NET Core 2.1 - Controller Caching Anonymous Method Function

FoxCouncil.Gist.AspNetCore.cs

// Copyright (c) Fox Council - License: MIT

/*
 * Usage Example:
 * [HttpGet]
 * public async Task<IActionResult> All()
 * {
 *      return await this.Cached(TimeSpan.FromMinutes(15), async () => {
 *          await _stuff.SomeLongTask();            
 *          return await _stuff.GetStuff();
 *      });
 * }
 */
namespace FoxCouncil.Gist.AspNetCore
{
    public static class Extensions
    {
        public static async Task<T> Cached<T>(this Controller controller, TimeSpan cacheLength, Func<Task<T>> fetchMethod)
        {
            var cacheSystem = controller.HttpContext.RequestServices.GetService<IMemoryCache>();
            var cacheKey = controller.Request.Path.ToString();

            if (cacheSystem.TryGetValue(cacheKey, out T result))
            {
                return result;
            }

            return cacheSystem.Set(cacheKey, await fetchMethod(), new MemoryCacheEntryOptions().SetSlidingExpiration(cacheLength));
        }
    }
}