.NET 6 - app.UseHttpLogging() does not log response modified by middleware-CodePudding

I have a .NET 6 Web API project. In a middleware I'm copying "x-correlation-id" header from request to response. When I run, it works ok and I see the x-correlation-id in response headers on client app.

The fragment of Program.cs is below:

var builder = WebApplication.CreateBuilder(args);
 
builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("x-correlation-id");
    logging.ResponseHeaders.Add("x-correlation-id"); 

});

var app = builder.Build(); 

app.Use(async (context, nextMiddleware) =>
{
    context.Response.OnStarting(() =>
    {
        if (context.Response.Headers.ContainsKey("x-correlation-id"))
            context.Response.Headers["x-correlation-id"] = "test "   context.Request.Headers["x-correlation-id"];
        else
            context.Response.Headers.Add("x-correlation-id", "test "   context.Request.Headers["x-correlation-id"]);
        return Task.FromResult(0);
    });
    await nextMiddleware();
});

app.UseHttpLogging();

I also want this modified response to be logged. I don't see this added header in logs generated by app.UseHttpLogging() line. When I add this header in controller such as Response.Headers["x-correlation-id"] = "test"; I can see that field logging.

How can I log this modified http response?

CodePudding user response：

HttpLoggingMiddleware processes response headers before it starts executing the response body, so you can work around by setting the header in the middleware, not in the OnStarting call:

app.Use(async (context, nextMiddleware) =>
{
    if (context.Response.Headers.ContainsKey("x-correlation-id"))
        context.Response.Headers["x-correlation-id"] = "test "   context.Request.Headers["x-correlation-id"];
    else
        context.Response.Headers.Add("x-correlation-id", "test "   context.Request.Headers["x-correlation-id"]);
    await nextMiddleware();
    
});
app.UseHttpLogging();

Another option - write your own middleware which will log the response headers after the response has started.