Is there a session start equivalent in .Net Core MVC 2.1? - asp.net-mvc

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

Answer 2

I use it in a live project. It works correctly. if you want to keep it when the application stops. You should use DistributedCache. For example, I'm using DistributedRedisCache.
Add to startup this code;
public void ConfigureServices(IServiceCollection services)
{
services.AddSession(options =>
{
options.IdleTimeout = TimeSpan.FromMinutes(60);
options.Cookie.HttpOnly = true;
});
// for redis distributed cache
//services.AddDistributedRedisCache(options =>
// {
// options.InstanceName = $"{Configuration["DistributedRedisCacheInstance"]}";
// options.Configuration = $"{Configuration["DistributedRedisCacheHost"]}";
// });
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor acc)
{
app.UseSession();
}
And add new session extension;
using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
using System.Text;
namespace SampleApp
{
public static class SessionExtensions
{
public static void SetObjectAsJson<T>(this ISession session, string key, T value)
{
session.Set(key, Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(value)));
}
public static T GetObjectFromJson<T>(this ISession session, string key)
{
session.TryGetValue(key, out byte[] dataByte);
string data = dataByte != null ? Encoding.UTF8.GetString(dataByte) : null;
return data == null ? default(T) : JsonConvert.DeserializeObject<T>(data);
}
}
}
And use get or set same this;
var sessionItem = httpContext.Session.GetObjectFromJson<string>("sessionItem");
//or
ContextProviderExtension.HttpContextAccessor.HttpContext.Session.SetObjectAsJson("sessionItem", sessionItem);
you need this extension;
using Microsoft.AspNetCore.Http;
using System;
namespace SampleApp
{
public static class ContextProviderExtension
{
static IHttpContextAccessor httpContextAccessor = null;
public static IHttpContextAccessor HttpContextAccessor
{
get { return httpContextAccessor; }
set
{
if (httpContextAccessor != null)
{
throw new Exception("");
}
httpContextAccessor = value;
}
}
}
}
I suppose it will work.
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using System.Threading.Tasks;
namespace SampleApp
{
public class SessionMiddleware
{
private readonly RequestDelegate _next;
public SessionMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task Invoke(HttpContext httpContext)
{
var sessionItem = httpContext.Session.GetObjectFromJson<string>("test");
if (sessionItem == null)
httpContext.Session.SetObjectAsJson<string>("test", httpContext.Session.Id);//httpContext.Session.Id or set a value
await _next.Invoke(httpContext);
}
}
public static class SessionMiddlewareExtensions
{
public static IApplicationBuilder UseSessionMiddleware(this IApplicationBuilder app)
{
return app.UseMiddleware<SessionMiddleware>();
}
}
}
and add startup.cs Configure method after app.UseSession();
app.UseSessionMiddleware();