cache-attribute.cs

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public class CachedAttribute : Attribute, IAsyncActionFilter
{
    private readonly int _timeToLiveSeconds;

    public CachedAttribute(int timeToLiveSeconds)
    {
        _timeToLiveSeconds = timeToLiveSeconds;
    }

    public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
    {
        //Get service settings for redis
        var cacheSettings = context.HttpContext.RequestServices.GetRequiredService<RedisOptions>();
        if (!cacheSettings.Enabled)
        {
            await next();
            return;
        }

        //Get the service, generate unique key from request
        var cacheService = context.HttpContext.RequestServices.GetRequiredService<IResponseCacheService>();
        var cacheKey = GenerateCacheKeyFromRequest(context.HttpContext.Request);

        //get data from cache
        var cachedResponse = await cacheService.GetCachedResponseAsync(cacheKey);

        //return response if data found in cache
        if (!string.IsNullOrEmpty(cachedResponse))
        {
            var contentResult = new ContentResult
            {
                Content = cachedResponse,
                ContentType = "application/json",
                StatusCode = 200
            };
            context.Result = contentResult;
            return;
        }

        //else, continue along request pipeline
        var executedContext = await next();

        //if the result of the request is sucessful, save the response in the cache for subsequent requests
        if (executedContext.Result is OkObjectResult okObjectResult)
        {
            await cacheService.CacheResponseAsync(cacheKey, okObjectResult.Value, TimeSpan.FromSeconds(_timeToLiveSeconds));
        }
    }

    private static string GenerateCacheKeyFromRequest(HttpRequest request)
    {
        var keyBuilder = new StringBuilder();

        keyBuilder.Append($"{request.Path}");

        foreach (var (key, value) in request.Query.OrderBy(x => x.Key))
        {
            keyBuilder.Append($"|{key}-{value}");
        }

        return keyBuilder.ToString();
    }
}