Middleware works in program.cs, but not when moved to it's own class-CodePudding

I'm using asp.net core 6, in my program.cs I have the following middleware, which is used to redirect the user when the statuscode is 404.

app.Use(async (ctx, next) =>
{
    await next();

    if (ctx.Response.StatusCode == 404 && !ctx.Response.HasStarted)
    {
        string originalPath = ctx.Request.Path.Value;
        ctx.Items["originalPath"] = originalPath;
        ctx.Request.Path = "/error/NotFound404";
        await next();
    }
});

This all works fine, but I want to clean up my program.cs a bit, so I decided to put this code in it's own class like this:

public class NotFoundMiddleware
{
    private readonly RequestDelegate _next;
    public NotFoundMiddleware(RequestDelegate next)
    {
        _next = next;
    }
    public async Task InvokeAsync(HttpContext httpContext)
    {

        if (httpContext.Response.StatusCode == 404 && !httpContext.Response.HasStarted)
        {
            string originalPath = httpContext.Request.Path.Value;
            httpContext.Items["originalPath"] = originalPath;
            httpContext.Request.Path = "/error/NotFound404";
        }
        
        await _next(httpContext);
    }
}

public static class NotFoundMiddlewareExtensions
{
    public static IApplicationBuilder CheckNotFound(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<NotFoundMiddleware>();
    }
}

And in my program.cs

app.CheckNotFound(); // on the same place the upp.Use... was before.

But then it doesn't work anymore.

I went through my code using breakpoints. and the InvokeAsync gets called on each request, The problem is that the httpContext.Response.StatusCode always returns 200.

CodePudding user response：

Your inline middleware calls next before testing the return value. The class only calls next after.