问题
I access the HttpContext in a Blazor server-side view to manually log out. I added this line to Startup.cs: services.AddHttpContextAccessor(); and inject it in the view with @inject IHttpContextAccessor HttpContextAccessor.
I've got a log out button which tries to execute this code:
await HttpContextAccessor.HttpContext.SignOutAsync("Cookies");
but I get the following error message:
System.InvalidOperationException: 'Headers are read-only, response has already started.'
How can I prevent this error?
回答1:
This tripped me up too, but you need the logout functionality to be on a Razor Page (not a Blazor component). Create a Logout page and put your logout code in the OnGetAsync() method.
Your logout button can then link to the logout page.
http://lightswitchhelpwebsite.com/Blog/tabid/61/EntryId/4316/A-Demonstration-of-Simple-Server-side-Blazor-Cookie-Authentication.aspx - this is a helpful example
回答2:
Don't use IHttpContextAccessor.
I guess that you're using ASP.NET Core Blazor authentication and authorization new system. If not, then start with it right now. Live is too short to be wasted over other things. This is the best product created so far for Blazor's authentication and authorization, and it is based on the Identity UI (This is not Blazor, of course). Additionally, there are a couple of Components which enable controlling the flow of authentication and authorization in your application, such as displaying a "Log in" button and a "Log out" button in your layout, interchangeably altering depending on your authentication state, etc.
Please, go to this page and start learning this excellent system, and then come here for specific issues you face: https://docs.microsoft.com/en-us/aspnet/core/security/blazor/?view=aspnetcore-3.0&tabs=visual-studio
Hope this helps...
来源：https://stackoverflow.com/questions/57249792/how-to-sign-out-over-httpcontext-in-server-side-blazor