How to create new UserManager object inside controller after DBContext changed

Question

I want to have a refreshed UserManager object after my DbContext changed with new connectionString inside the Controller, I have injected the UserManager in the Controller but it's obvious that it will always have the last DbContext reference from DI, not to the newly created dbcontext.

I have tried like below.

this.DbContext = new ApplicationDbContext(Configuration, optionsBuilder.Options);
this._userManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(DbContext), null, new PasswordHasher<ApplicationUser>(), null, null, null, null, null, null);

It works fine but it lacking most of the UserManager functionality like _userManager.CheckPasswordAsync(user, loginModel.Password) as I'm passing most of the parameter as null. What should I do to get a fully working UserManger with new DbContext in simplest way?

Just curious why you’d want to do such a thing ? – Ceemah Four Dec 28 '20 at 10:08 — Ceemah Four, Dec 28 '20 at 10:08

Zhi Lv · Answer 1 · 2020-12-29T10:14:49.563

You can try to create a service and use the UserManger in the service, then, configure the service using the Transient operations in the Startup.ConfigureServices method. The Transient operations are always different, a new instance is created with every retrieval of the service. Then, you could use this service in the controller. Please check the following steps:

create a UserManagerRepository service (in this service you can create methods and use the UserManager methods):

public interface IUserManagerRepository
{
    void Write(string message);
}
public class UserManagerRepository : IUserManagerRepository, IDisposable
{
    private bool _disposed;
    private readonly UserManager<IdentityUser> _userManager;

    public UserManagerRepository(UserManager<IdentityUser> userManager)
    {
        _userManager = userManager;
    }

    public void Write(string message)
    {
        // _userManager.ChangePasswordAsync()
        Console.WriteLine($"UserManagerRepository: {message}");
    }

    public void Dispose()
    {
        if (_disposed)
            return;

        Console.WriteLine("UserManagerRepository.Dispose");
        _disposed = true;
    }
}

Confiture the service using the following code in the Startup.ConfigureServices method:

 services.AddTransient<IUserManagerRepository, UserManagerRepository>();

After that, call the services manually in the controller action method.

    public IActionResult Index()
    {
        var services = this.HttpContext.RequestServices;
        var log = (IUserManagerRepository)services.GetService(typeof(IUserManagerRepository));

        log.Write("Index method executing");
         
        var log2 = (IUserManagerRepository)services.GetService(typeof(IUserManagerRepository));

        log2.Write("Index method executing");
        var log3 = (IUserManagerRepository)services.GetService(typeof(IUserManagerRepository));

        log3.Write("Index method executing"); 
        return View();
    }

screenshot as below:

Reference:

Tutorial: Use dependency injection in .NET

Dependency injection guidelines

Dependency injection in ASP.NET Core

so after calling the service again the userManager will be initialized with the newly created AppDbContext? — Sabir Hossain, Dec 29 '20 at 12:26
the _userManager still holds reference to the old dbContext, the new dbContext has a different connectionString — Sabir Hossain, Dec 29 '20 at 12:46
@SabirHossain of course, because the code injects `UserManager` which is provided by the identity model, that still depends on the configured `DbContext` (in your app startup). This answer is definitely not what you want. — Hopeless, Dec 29 '20 at 17:38
I knew that, @Hopeless what can I do to refresh the UserManger with the newly created DbContext, you can see how I'm doing that but I need a fully functional UserManager — Sabir Hossain, Dec 30 '20 at 11:38

score -1 · Answer 2 · answered Dec 28 '20 at 08:53

Use Dependency Injection, that's how all of the mentioned tools are meant to be consumed.

private DbContext DbContext { get;}

private UserManager<IdentityUser> UserManager { get; } 

public MyController(DbContext dbContext, UserManager<IdentityUser> userManager)
{
    DbContext = dbContext;
    UserManager = userManager;
}

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-5.0

And here's a page on how to setup Dependency Injection for EF Core:

https://learn.microsoft.com/en-us/ef/core/dbcontext-configuration/#dbcontext-in-dependency-injection-for-aspnet-core

Assuming you already have services.AddDefaultIdentity(...) and services.AddDbContext(...), injecting of UserManager and YourProjectDbContext should inherently just work in your Controllers.

How to create new UserManager object inside controller after DBContext changed

2 Answers2