Static property in asp.net core middleware is shared between requests?

Question

I have a static class User with a static property Username. I set this property in a middleware on each url request. Then i show the Username to user in the header of site.

On every request, this static property is set and then shown in the view. I am assuming that each request will have it's own (correct) value in the property and the value does not get shared between different requests?

So, if request one has value adam and request 2 has value john, adam will see adam and john will see john in the header? This is working okay in my app but just want to make sure that conceptually it is right?

Answer 1

This as you have already been informed is a good candidate for HttpContext.Items with a unique object key to avoid key collisions. As each context is unique for each request they will allow the values to not get shared between the different requests. You are not setting the value as a static value on the middle ware but on the current request context.

public class SampleMiddleware {
    public static readonly object SampleKey = new Object();

    public async Task Invoke(HttpContext httpContext) {
        httpContext.Items[SampleKey] = "some value";
        // additional code omitted
    }
}

Other code can access the value stored in HttpContext.Items using the key exposed by the middleware class:

public class HomeController : Controller {
    public IActionResult Index() {
        string value = HttpContext.Items[SampleMiddleware.SampleKey];
    }
}

Reference Introduction to session and application state in ASP.NET Core

So only the key is static but the value set in the items will be unique for each request. That means in your case that if request one has value adam and request 2 has value john, adam will see adam and john will see john in the header