How to access the Session in ASP.NET Core via static variable?

Question

In earlier version of Asp.Net session can be accessed in any page like a static variable using

System.Web.HttpContext.Current.Session[\"key\"]

Answer 1

In Startup.ConfigureServices you have to add the service

services.AddSession();

and in the method Configure you have to use it (important: call before app.UseMvc())

app.UseSession();

Now you can use it in your controllers (if derived from Controller). You can store

var data = new byte[] { 1, 2, 3, 4 };
HttpContext.Session.Set("key", data); // store byte array

byte[] readData;
HttpContext.Session.TryGetValue("key", out readData); // read from session

When you import the namespace Microsoft.AspNetCore.Http then you can use SetString and SetInt32 as well.

using Microsoft.AspNetCore.Http;

HttpContext.Session.SetString("test", "data as string"); // store string
HttpContext.Session.SetInt32("number", 4711); // store int

int ? number = HttpContext.Session.GetInt32("number");

Outside the controller you do not have access to the HttpContext, but you can inject an IHttpContextAccessor instance like described in this answer