MVC 5 Seed Users and Roles

Here is example of usual Seed approach:

protected override void Seed(SecurityModule.DataContexts.IdentityDb context)
{
    if (!context.Roles.Any(r => r.Name == "AppAdmin"))
    {
        var store = new RoleStore<IdentityRole>(context);
        var manager = new RoleManager<IdentityRole>(store);
        var role = new IdentityRole { Name = "AppAdmin" };

        manager.Create(role);
    }

    if (!context.Users.Any(u => u.UserName == "founder"))
    {
        var store = new UserStore<ApplicationUser>(context);
        var manager = new UserManager<ApplicationUser>(store);
        var user = new ApplicationUser {UserName = "founder"};

        manager.Create(user, "ChangeItAsap!");
        manager.AddToRole(user.Id, "AppAdmin");
    }
}

I used package-manager "update-database". DB and all tables were created and seeded with data.

It's a small addition, but to anyone having the "UserId not found." message when trying to seed: (Tom Regan had this question in the comments, and I was stuck on it myself for a while)

This means that the manager.Create(user, "ChangeItAsap!") was not successful. This might have a different reason, but for me it was because my password was not succeeding its validation.

I had a custom passwordvalidator, which was not being called when seeding the database, so the validation rules i was used to (minlength 4 instead of default 6) did not apply. Make sure your password (and all other fields for that matter) is passing validation.