How to get Identity User outside Razor Pages in Blazor Server-side? - asp.net

Question

I am working on a Blazor Server-Side application, using Microsoft Identity, Entity Framework and a multitenant approach with shared Db.
I have extended the IdentityUser class so that I could have the TenantId in the AspNetUser Table
public class ApplicationUser : IdentityUser
{
public int TenantId { get; set; }
}
}
Then I have applied a general query filter to my dbModel based on the TenantId
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Employee>().HasQueryFilter(a => a.TenantId == TenantId);
}
In my blazor page I can call this function
public async Task SetTenant()
{
var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
var user = authState.User;
ApplicationUser = await UserManager.FindByNameAsync(user.Identity.Name);
var TenatId = ApplicationUser.TenantId;
}
Finally in my service I can get a list of Employees with the right TenantId
public Task<Employee[]> GetEmployees(int TenatntID)
{
using (var ctx = new ProgramDbContext(TenantId))
{
return Task.FromResult(ctx.Employee.Select(d => new Employee
{
Id = d.Id,
TenantId = d.TenantId,
Name= d.Name,
}).ToArray());
}
}
With this approach, everytime I want to call a function to get DB's Data, I need to identity the user and get the TenantId, then call the specific function and pass the tenantID to it.
I would like to know if my approach is completely wrong to implement this type of solution, for example:
Is it possible to add a Singleton service of an ApplicationUser, so that once is is identified after login, i can inject the service in every class where i need the ApplicationUser.TenantId?
Is it possible to identify and authenticate the Application User outside a blazor class? for example a plain C# class? I was able to pass the AuthenticationStateProvider and UserManager in the constructor of my Service class, but I cant await a function inside the constructor to actually get the ApplicationUser object.
public CaronteWebService(AuthenticationStateProvider authenticationStateProvider, UserManager userManager)
{
_AuthenticationStateProvider = authenticationStateProvider;
_userManager = userManager;
}
UserManager<ApplicationUser> _userManager;
public ApplicationUser ApplicationUser { get; set; }
AuthenticationStateProvider _AuthenticationStateProvider { get; set; }