ASP.NET Core 2.0 Session State

Problem

How to store data in session state using ASP.NET Core.

Solution

Using an empty project from a previous post, amend Startup class ConfigureServicee() method, add services for session and its backing store,

public void ConfigureServices(
IServiceCollection services)
{
services.AddDistributedMemoryCache();
services.AddSession();
}

Add the session middleware in Configure() method,

public void Configure(
IApplicationBuilder app,
IHostingEnvironment env)
{
app.UseSession();
app.Use(async (context, next) =>
{
context.Session.SetString("GreetingMessage", "Hello Session State");
await next();
});
app.Run(async (context) =>
{
var message = context.Session.GetString("GreetingMessage");
await context.Response.WriteAsync($"{message}");
});
}

Discussion

We can use session in order to share information between different HTTP requests coming from a single browser. The data is stored in a cache (IDistributedCache implementation to be specific) and accessed via HttpContext.Session property.

A cookie is stored in browser to correlated the HTTP requests. The default name of this cookie is .AspNet.Session.

During the configuration of session services we can set various properties,

HttpOnly - sets whether cookie is accessible through JavaScript. Default is true, which means it can’t be accessed via scripts on the client-side.
Name - used to override the default cookie name.
SecurePolicy - determines if session cookie is only transmitted via HTTPS requests.
IdleTimeout - sets the time for session expiry, each request resets the timeout. Default is 20 mintues.

public void ConfigureServices(
IServiceCollection services)
{
services.AddDistributedMemoryCache();
services.AddSession(options =>
{
options.Cookie.HttpOnly = true;
options.Cookie.Name = ".Fiver.Session";
options.Cookie.SecurePolicy = CookieSecurePolicy.Always;
options.IdleTimeout = TimeSpan.FromMinutes(10);
});
}

Storing Objects

HttpContext.Session (or ISession that it implements) does not provide a built-in way to store complex objects, however, we can serialise objects into JSON strings to achieve this,

public static class SessionExtensions
{
public static void SetObject<T>(this ISession session, string key, T value)
{
session.SetString(key, JsonConvert.SerializeObject(value));
}
public static T GetObject<T>(this ISession session, string key)
{
var value = session.GetString(key);
return value == null ? default(T) :
JsonConvert.DeserializeObject<T>(value);
}
}

Now we can use these extension methods like below,

public void Configure(
IApplicationBuilder app,
IHostingEnvironment env,
ILoggerFactory loggerFactory)
{
app.UseSession();
app.Use(async (context, next) =>
{
context.Session.SetObject("CurrentUser",
new UserInfo { Username = "James", Email = "[email protected]" });
await next();
});
app.Run(async (context) =>
{
var user = context.Session.GetObject<UserInfo>("CurrentUser");
await context.Response.WriteAsync($"{user.Username}, {user.Email}");
});
}

Accessing via Dependency Injection

To access session using dependency injection you could use IHttpContextAccessor (via constructor), which gives you access to HttpContext.

Source Code

GitHub

4 Comments

Join the conversation! Your thoughts help the community grow.

Shamsher Singh7y ago
How to handle if session timeout in Ajax call
David Alejandro García García8y ago
Can you please help with a sessions issue with asp net core 2? https://www.c-sharpcorner.com/forums/aspnet-core-2-no-service-for-httpcontext-sessions-issue
Vignesh Mani9y ago
Nice one. Thank you for sharing
- Guest User9y ago
  Thanks Vignesh, hope you like the other articles too.