How to change type of id in Microsoft.AspNet.Identity.EntityFramework.IdentityUser

Using a Stefan Cebulak's answer and a Ben Foster's great blog article ASP.NET Identity Stripped Bare I have came up with below solution, which I have applied to ASP.NET Identity 2.0 with a generated by Visual Studio 2013 AccountController.

The solution uses an integer as a primary key for users and also allows to get an ID of currently logged in user without making a trip to the database.

Here are the steps, you need to follow:

1. Create custom user-related classes

By default, the AccountController uses classes, which are using string, as a type of a primary key. We need to create below classes, which will use an int instead. I have defined all below classes in one file: AppUser.cs

public class AppUser :
    IdentityUser<int, AppUserLogin, AppUserRole, AppUserClaim>,
    IUser<int>
{

}

public class AppUserLogin : IdentityUserLogin<int> { }

public class AppUserRole : IdentityUserRole<int> { }

public class AppUserClaim : IdentityUserClaim<int> { }

public class AppRole : IdentityRole<int, AppUserRole> { }

It will also be useful, to have a custom ClaimsPrincipal, which will easily expose User's ID

public class AppClaimsPrincipal : ClaimsPrincipal
{
    public AppClaimsPrincipal( ClaimsPrincipal principal ) : base( principal )
    { }

    public int UserId
    {
        get { return int.Parse(this.FindFirst( ClaimTypes.Sid ).Value); }
    }
}

2. Create a custom IdentityDbContext

Our application's database context will extend IdentityDbContext, which implements by default all authentication-related DbSets. Even if DbContext.OnModelCreating is an empty method, I am not sure about the IdentityDbContext.OnModelCreating, so when overriding, remember to call base.OnModelCreating( modelBuilder ) AppDbContext.cs

public class AppDbContext :
    IdentityDbContext<AppUser, AppRole, int, AppUserLogin, AppUserRole, AppUserClaim>
{
    public AppDbContext() : base("DefaultConnection")
    {
        // Here use initializer of your choice
        Database.SetInitializer( new CreateDatabaseIfNotExists<AppDbContext>() );
    }


    // Here you define your own DbSet's



    protected override void OnModelCreating( DbModelBuilder modelBuilder )
    {
        base.OnModelCreating( modelBuilder );

        // Here you can put FluentAPI code or add configuration map's
    }
}

3. Create custom UserStore and UserManager, which will use above

AppUserStore.cs

public interface IAppUserStore : IUserStore<AppUser, int>
{

}

public class AppUserStore :
    UserStore<AppUser, AppRole, int, AppUserLogin, AppUserRole, AppUserClaim>,
    IAppUserStore
{
    public AppUserStore() : base( new AppDbContext() )
    {

    }

    public AppUserStore(AppDbContext context) : base(context)
    {

    }
}

AppUserManager.cs

public class AppUserManager : UserManager<AppUser, int>
{
    public AppUserManager( IAppUserStore store ) : base( store )
    {

    }
}

4. Modify AccountController to use your custom classes

Change all UserManager to AppUserManager, UserStore to AppUserStore etc. Take an example of this constructors:

public AccountController()
    : this( new AppUserManager( new AppUserStore( new AppDbContext() ) ) )
{
}

public AccountController(AppUserManager userManager)
{
    UserManager = userManager;
}

5. Add user's ID as a claim to ClaimIdentity stored in a cookie

In step 1, we have created AppClaimsPrincipal, which exposes UserId taken out of ClaimType.Sid. However, to have this claim available, we need to add it, when logging in the user. In AccountController a SingInAsync method is responsible for logging in. We need to add a line to this method, to add the claim.

private async Task SignInAsync(AppUser user, bool isPersistent)
{
    AuthenticationManager.SignOut(DefaultAuthenticationTypes.ExternalCookie);
    ClaimsIdentity identity = await UserManager.CreateIdentityAsync(user, DefaultAuthenticationTypes.ApplicationCookie);

    // Extend identity claims
    identity.AddClaim( new Claim( ClaimTypes.Sid, user.Id.ToString() ) );

    AuthenticationManager.SignIn(new AuthenticationProperties() { IsPersistent = isPersistent }, identity);
}

6. Create a BaseController with a CurrentUser property

To have an easy access to a currently logged in user's ID in your controllers, create an abstract BaseController, from which your controllers will derive. In the BaseController, create a CurrentUser as follows:

public abstract class BaseController : Controller
{
    public AppClaimsPrincipal CurrentUser
    {
        get { return new AppClaimsPrincipal( ( ClaimsPrincipal )this.User ); }
    }


    public BaseController()
    {

    }
}

7. Inherit your controllers from BaseController and enjoy

From now on, you can use CurrentUser.UserId in your controllers to access an ID of a currently logged in user without trips to the database. You can use it, to query only objects, which belong to the user.

You don't have to take care of auto generation of user primary keys - no surprise, Entity Framework by default uses Identity for integer primary keys, when creating tables.

Warning! Keep in mind, that if you implement it in already released project, for already logged in users ClaimsType.Sid will not exist and FindFirst will return null in AppClaimsPrincipal. You need to either force logout all users or handle this scenario in AppClaimsPrincipal

So if you want int ids, you need to create your own POCO IUser class and implement your IUserStore for your custom IUser class in the 1.0 RTM release.

This is something we didn't have time to support, but I'm looking into making this easy(ier) in 1.1 right now. Hopefully something will be available in the nightly builds soon.

Updated with 1.1-alpha1 example: How to get nightly builts

If you update to the latest nightly bits, you can try out the new 1.1-alpha1 apis which should make this easier now: Here's what plugging in Guids instead of strings should look like for example

    public class GuidRole : IdentityRole<Guid, GuidUserRole> { 
        public GuidRole() {
            Id = Guid.NewGuid();
        }
        public GuidRole(string name) : this() { Name = name; }
    }
    public class GuidUserRole : IdentityUserRole<Guid> { }
    public class GuidUserClaim : IdentityUserClaim<Guid> { }
    public class GuidUserLogin : IdentityUserLogin<Guid> { }

    public class GuidUser : IdentityUser<Guid, GuidUserLogin, GuidUserRole, GuidUserClaim> {
        public GuidUser() {
            Id = Guid.NewGuid();
        }
        public GuidUser(string name) : this() { UserName = name; }
    }

    private class GuidUserContext : IdentityDbContext<GuidUser, GuidRole, Guid, GuidUserLogin, GuidUserRole, GuidUserClaim> { }
    private class GuidUserStore : UserStore<GuidUser, GuidRole, Guid, GuidUserLogin, GuidUserRole, GuidUserClaim> {
        public GuidUserStore(DbContext context)
            : base(context) {
        }
    }
    private class GuidRoleStore : RoleStore<GuidRole, Guid, GuidUserRole> {
        public GuidRoleStore(DbContext context)
            : base(context) {
        }
    }

    [TestMethod]
    public async Task CustomUserGuidKeyTest() {
        var manager = new UserManager<GuidUser, Guid>(new GuidUserStore(new GuidUserContext()));
        GuidUser[] users = {
            new GuidUser() { UserName = "test" },
            new GuidUser() { UserName = "test1" }, 
            new GuidUser() { UserName = "test2" },
            new GuidUser() { UserName = "test3" }
            };
        foreach (var user in users) {
            UnitTestHelper.IsSuccess(await manager.CreateAsync(user));
        }
        foreach (var user in users) {
            var u = await manager.FindByIdAsync(user.Id);
            Assert.IsNotNull(u);
            Assert.AreEqual(u.UserName, user.UserName);
        }
    }

@HaoKung

I've succeeded to make int id's with your nightly builds. User.Identity.GetUserId() problem is still there, but i just did int.parse() for now.

The biggest suprise was that i did not need to create ID by myself, db was made with identity id and it was somehow automatically set for new users Oo...

Model:

    public class ApplicationUser : IdentityUser<int, IntUserLogin, IntUserRole, IntUserClaim>
{
    public ApplicationUser()
    {
    }
    public ApplicationUser(string name) : this() { UserName = name; }
}

public class ApplicationDbContext : IntUserContext
{
    public ApplicationDbContext()
    {

    }
}

private class IntRole : IdentityRole<int, IntUserRole>
{
    public IntRole()
    {
    }
    public IntRole(string name) : this() { Name = name; }
}
private class IntUserRole : IdentityUserRole<int> { }
private class IntUserClaim : IdentityUserClaim<int> { }
private class IntUserLogin : IdentityUserLogin<int> { }
private class IntUserContext : IdentityDbContext<ApplicationUser, IntRole, int, IntUserLogin, IntUserRole, IntUserClaim>
{
    public IntUserContext()
        : base("DefaultConnection")
    {

    }
}
private class IntUserStore : UserStore<ApplicationUser, IntRole, int, IntUserLogin, IntUserRole, IntUserClaim>
{
    public IntUserStore(DbContext context)
        : base(context)
    {

    }
}
private class IntRoleStore : RoleStore<IntRole, int, IntUserRole>
{
    public IntRoleStore(DbContext context)
        : base(context)
    {
    }
}

Controller:

        public AccountController()
        : this(new UserManager<ApplicationUser, int>(new IntUserStore(new ApplicationDbContext())))
    {
    }

    public AccountController(UserManager<ApplicationUser, int> userManager)
    {
        UserManager = userManager;
    }

    public UserManager<ApplicationUser, int> UserManager { get; private set; }

Hope release build will come soon :D...

P.S. Can't write comments so i did an answer, sorry.