ASP.NET MVC – Set custom IIdentity or IPrincipal

ASP.NET MVC – Set custom IIdentity or IPrincipal

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I decided to use IPrincipal instead of IIdentity because it means I don’t have to implement both IIdentity and IPrincipal.

  1. Create the interface
    interface ICustomPrincipal : IPrincipal
    {
        int Id { get; set; }
        string FirstName { get; set; }
        string LastName { get; set; }
    }
  2. CustomPrincipal
    public class CustomPrincipal : ICustomPrincipal
    {
        public IIdentity Identity { get; private set; }
        public bool IsInRole(string role) { return false; }
    
        public CustomPrincipal(string email)
        {
            this.Identity = new GenericIdentity(email);
        }
    
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }
  3. CustomPrincipalSerializeModel – for serializing custom information into userdata field in FormsAuthenticationTicket object.
    public class CustomPrincipalSerializeModel
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }
  4. LogIn method – setting up a cookie with custom information
    if (Membership.ValidateUser(viewModel.Email, viewModel.Password))
    {
        var user = userRepository.Users.Where(u => u.Email == viewModel.Email).First();
    
        CustomPrincipalSerializeModel serializeModel = new CustomPrincipalSerializeModel();
        serializeModel.Id = user.Id;
        serializeModel.FirstName = user.FirstName;
        serializeModel.LastName = user.LastName;
    
        JavaScriptSerializer serializer = new JavaScriptSerializer();
    
        string userData = serializer.Serialize(serializeModel);
    
        FormsAuthenticationTicket authTicket = new FormsAuthenticationTicket(
                 1,
                 viewModel.Email,
                 DateTime.Now,
                 DateTime.Now.AddMinutes(15),
                 false,
                 userData);
    
        string encTicket = FormsAuthentication.Encrypt(authTicket);
        HttpCookie faCookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
        Response.Cookies.Add(faCookie);
    
        return RedirectToAction("Index", "Home");
    }
  5. Global.asax.cs – Reading cookie and replacing HttpContext.User object, this is done by overriding PostAuthenticateRequest
    protected void Application_PostAuthenticateRequest(Object sender, EventArgs e)
    {
        HttpCookie authCookie = Request.Cookies[FormsAuthentication.FormsCookieName];
    
        if (authCookie != null)
        {
            FormsAuthenticationTicket authTicket = FormsAuthentication.Decrypt(authCookie.Value);
    
            JavaScriptSerializer serializer = new JavaScriptSerializer();
    
            CustomPrincipalSerializeModel serializeModel = serializer.Deserialize<CustomPrincipalSerializeModel>(authTicket.UserData);
    
            CustomPrincipal newUser = new CustomPrincipal(authTicket.Name);
            newUser.Id = serializeModel.Id;
            newUser.FirstName = serializeModel.FirstName;
            newUser.LastName = serializeModel.LastName;
    
            HttpContext.Current.User = newUser;
        }
    }
  6. Access in Razor views
    @((User as CustomPrincipal).Id)
    @((User as CustomPrincipal).FirstName)
    @((User as CustomPrincipal).LastName)

and in code:

    (User as CustomPrincipal).Id
    (User as CustomPrincipal).FirstName
    (User as CustomPrincipal).LastName

I think the code is self-explanatory. If it isn’t, let me know.

Additionally to make the access even easier you can create a base controller and override the returned User object (HttpContext.User):

public class BaseController : Controller
{
    protected virtual new CustomPrincipal User
    {
        get { return HttpContext.User as CustomPrincipal; }
    }
}

and then, for each controller:

public class AccountController : BaseController
{
    // ...
}

which will allow you to access custom fields in code like this:

User.Id
User.FirstName
User.LastName

But this will not work inside views. For that you would need to create a custom WebViewPage implementation:

public abstract class BaseViewPage : WebViewPage
{
    public virtual new CustomPrincipal User
    {
        get { return base.User as CustomPrincipal; }
    }
}

public abstract class BaseViewPage<TModel> : WebViewPage<TModel>
{
    public virtual new CustomPrincipal User
    {
        get { return base.User as CustomPrincipal; }
    }
}

Make it a default page type in Views/web.config:

<pages pageBaseType="Your.Namespace.BaseViewPage">
  <namespaces>
    <add namespace="System.Web.Mvc" />
    <add namespace="System.Web.Mvc.Ajax" />
    <add namespace="System.Web.Mvc.Html" />
    <add namespace="System.Web.Routing" />
  </namespaces>
</pages>

and in views, you can access it like this:

@User.FirstName
@User.LastName

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