Posted 07/25/2025

Response Caching

Setting the Cache-Control header – ASP.NET has built-in support for response caching, but it is mainly designed for MVC. For web services (without MVC), it can be implemented by adding an output filter that sets the Cache-Control header after the request is processed.

    endpointRouteBuilder.MapGet($"users/",
        async (int id, [FromServices] IGetBatchClaimsFilterOptionsQueryHandler handler, CancellationToken cancellationToken) =>
            await handler.SendAsync(id, cancellationToken))
        .ProducesHttpDataResponse<UserDto>()
        .AddResponseCacheHourHeader()

    public static class HttpResponseCachingConfiguration
    {
        private const int TenMinutes = 60 * 10;
        private const int Hour = 60 * 60;
        public static RouteHandlerBuilder AddResponseCacheTenMinutesHeader(this RouteHandlerBuilder routeHandlerBuilder)
            => routeHandlerBuilder.AddResponseCacheHeader(TenMinutes);

        public static RouteHandlerBuilder AddResponseCacheHourHeader(this RouteHandlerBuilder routeHandlerBuilder)
            => routeHandlerBuilder.AddResponseCacheHeader(Hour);

        public static RouteHandlerBuilder AddResponseCacheHeader(this RouteHandlerBuilder routeHandlerBuilder, int maxAgeInSeconds)
            => routeHandlerBuilder.AddEndpointFilter(async (context, next) =>
            {
                context.HttpContext.Response.Headers.CacheControl = $"public,max-age={maxAgeInSeconds}";
                return await next(context);
            });
    }

With the Cache-Control header, responses can be cached on the client or along the way (e.g., on a proxy). For client-side caching, the browser must not have caching disabled. The browser then handles the cached responses.