.NET Core身份UserManager始终为用户返回null

Question

我目前正在尝试将Identity的UserManager类连接到一个简单的应用程序。尝试这样做时，.FindByEmailAsync以及尝试查找用户的任何其他方法总是向我返回空用户。 UserManager本身不为null，但似乎无法正确找到我的任何用户。我的应用程序中的所有内容都使用相同的数据库，并且我已验证用户是否存在于数据库中。

[Route("api/[controller]")]
[ApiController]
public class UsersController : ControllerBase
{
    private SignInManager<ApplicationUser> _signInManager;
    private UserManager<ApplicationUser> _userManager;

    public UsersController(UserManager<ApplicationUser> userManager, SignInManager<ApplicationUser> signInManager)
    {
        _userManager = userManager;
        _signInManager = signInManager;
    }

    public async Task<ActionResult<ApplicationUser>> Get()
    {
        //this returns null
        var user = await _userManager.FindByEmailAsync("admin@admin.com");

        //this works
        using (var db = new ApplicationDbContext(GetDbOptions()))
        {
            return db.Users.Single(x => x.Email == "admin@admin.com")
        }
    }

}

我的Startup.cs类如下：

services.AddDbContext<ApplicationDbContext>(options =>

options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

services.AddIdentityCore<ApplicationUser>()
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddDefaultTokenProviders();
    //.AddSignInManager<SignInManager<ApplicationUser>>() tried adding these with no success- same behavior
    //.AddUserManager<UserManager<ApplicationUser>>();

正在将用户植入数据库，如下所示：

    private static void SeedIdentityUsers(IServiceScope serviceScope)
    {
        var context = serviceScope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
        var PasswordHash = new PasswordHasher<ApplicationUser>();

        if (!context.Users.Any(u => u.UserName == "admin@admin.com"))
        {
            var user = new ApplicationUser
            {
                UserName = "admin@admin.com",
                Email = "admin@admin.com",
            };

            user.PasswordHash = PasswordHash.HashPassword(user, "somepassword");
            context.Users.Add(user);
            context.SaveChanges();
        }
    }