Is there a session start equivalent in .Net Core MVC 2.1?

Question

In MVC 5 you could assign a value to session in global.asx when the session started. Is there a way you can do this in .Net Core MVC? I have session configured but in the middleware it seems to get called on every request.

Answer 1

nercan's solution will work, but I think I found a solution that requires less code and may have other advantages.

First, wrap DistributedSessionStore like this:

using System;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Session;
using Microsoft.Extensions.Caching.Distributed;
using Microsoft.Extensions.Logging;

public interface IStartSession
{
    void StartSession(ISession session);
}

public class DistributedSessionStoreWithStart : ISessionStore
{
    DistributedSessionStore innerStore;
    IStartSession startSession;
    public DistributedSessionStoreWithStart(IDistributedCache cache, 
        ILoggerFactory loggerFactory, IStartSession startSession)
    {
        innerStore = new DistributedSessionStore(cache, loggerFactory);
        this.startSession = startSession;
    }

    public ISession Create(string sessionKey, TimeSpan idleTimeout, 
        TimeSpan ioTimeout, Func<bool> tryEstablishSession, 
        bool isNewSessionKey)
    {
        ISession session = innerStore.Create(sessionKey, idleTimeout, ioTimeout,
             tryEstablishSession, isNewSessionKey);
        if (isNewSessionKey)
        {
            startSession.StartSession(session);
        }
        return session;
    }
}

Then register this new class in Startup.cs:

class InitSession : IStartSession
{
    public void StartSession(ISession session)
    {
        session.SetString("Hello", "World");
    }
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        ...
        services.AddSingleton<IStartSession, InitSession>();
        services.AddSingleton<ISessionStore, DistributedSessionStoreWithStart>();
        services.AddSession();
        ...
    }

Full code is here: https://github.com/SurferJeffAtGoogle/scratch/tree/master/StartSession/MVC