Getting ObjectResult value from HttpContext

Question

Introducing JustController:

// many using directives

namespace MyWebApiProject.Controllers
{
    [Route("api/[controller].[action]")]
    [ApiController]
    public class JustController : ControllerBase
    {
        [HttpPost]
        public async Task<ActionResult> GetById(/*Model Class*/ body)
        {
            return StatusCode(/* http status code */, "THIS IS NEEDED VALUE"); // <- Look at this!
        }
    }
}

We also have this middleware:

// many using directives

public class StatusCodeMiddleware
{
    private readonly RequestDelegate _next;

    public StatusCodeMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext httpContext)
    {
        await _next(httpContext);
        /*
            How to get "THIS IS NEEDED VALUE" from HttpContext here
        */
    }
}

public static class StatusCodeMiddlewareExtensions // For convenient use in Startup.cs
{
    public static void ConfigureCustomStatusCodeMiddleware(this IApplicationBuilder app)
    {
        app.UseMiddleware<StatusCodeMiddleware>();
    }
}

Startup.cs:

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.ConfigureCustomStatusCodeMiddleware();

    app.UseRouting();

    app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
}

How do I get "THIS IS NEEDED VALUE" from HttpContext inside the InvokeAsync() method, inside of StatusCodeMiddleware?

Thanks in advance! I really hope the Stack Overflow audience helps me! I googled the solution to this problem for 2 days so I did not find anything. Sorry for my bad English!

Answer 1

In order to do this you need to fiddle a little with streams. It's not pretty but if you really need to do this in a middleware you could do it like suggested in the answer here:

public async Task InvokeAsync(HttpContext httpContext)
{
    Stream originalBody = context.Response.Body;

    try
    {
        using (var memStream = new MemoryStream())
        {
            context.Response.Body = memStream;

            await next(context);

            memStream.Position = 0;
            string responseBody = new StreamReader(memStream).ReadToEnd();

            // Here responseBody == "THIS IS NEEDED VALUE"

            memStream.Position = 0;
            await memStream.CopyToAsync(originalBody);
        }
    }
    finally
    {
        context.Response.Body = originalBody;
    }
}