How to get HttpContext.Current.Session in ASP.NET Core?

Use like this:

HttpContext.Session.SetString("priceModel", JsonConvert.SerializeObject(customobject));
var priceDetails = HttpContext.Session.GetString("priceModel");

Make sure below points in startup class:

1. AddSession in ConfigureServices method

   services.AddSession();
   

2. Usesession in configure method:

   app.UseSession();
   

you don't have System.Web.HttpContext.Current.Session in ASP.NET Core. To access session in non-controller class step1: First, register the following service in Startup.ConfigureServices;

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

step2: register a class (example - TestOrder) where you want to access the Session in

Startup.ConfigureServices;
services.AddScoped<TestOrder>();

Now, in TestOrderclass, add the following code.

private readonly IHttpContextAccessor _httpContextAccessor;    
private readonly ISession _session;    
public TestOrder(IHttpContextAccessor httpContextAccessor)    
   {    
        _httpContextAccessor = httpContextAccessor;    
        _session = _httpContextAccessor.HttpContext.Session;    
    }

The above code is receiving IHttpContextAccessor object through dependency injection and then, it is storing Sessions in a local variable.

Did you test Microsoft doc, a sample is like below

public const string SessionKeyName = "_Name";
public const string SessionKeyAge = "_Age";
const string SessionKeyTime = "_Time";

 // Requires: using Microsoft.AspNetCore.Http;
    if (string.IsNullOrEmpty(HttpContext.Session.GetString(SessionKeyName)))
    {
        HttpContext.Session.SetString(SessionKeyName, "The Doctor");
        HttpContext.Session.SetInt32(SessionKeyAge, 773);
    }

    var name = HttpContext.Session.GetString(SessionKeyName);
    var age = HttpContext.Session.GetInt32(SessionKeyAge);

The recommended approach is to register a dependency using the built-in dependency injection container. Inject IHttpContextAccessor into the corresponding service.

public class UserRepository : IUserRepository
    {
        private readonly IHttpContextAccessor _httpContextAccessor;

        public UserRepository(IHttpContextAccessor httpContextAccessor)
        {
            _httpContextAccessor = httpContextAccessor;
        }

        public void LogCurrentUser()
        {
            var username = _httpContextAccessor.HttpContext.Session.GetString("UserName");
            service.LogAccessRequest(username);
        }
    }

For more details, refer to this link