如何在 .NET Core 中检索当前登录用户的 email？

Question

I've gone through many SO threads about this and I've found a way that works (@UserManager.FindByNameAsync(UserManager.GetUserName(User)).Result.Email) however, I need the email to be assigned to a variable within the code for the page so that I can use it for something else and the class for this isn't a controller class so i'm looking to do this outside the controller.

I'm getting an error that Object reference not set to an instance of an object. on the Email address: @user.Email line within the View when I run it and when changing the return type of the Index() function in HomeController to PrescriptionModel I get the error There is no argument given that corresponds to the required formal parameter 'logger' of PrescriptionModel.PrescriptionModel(ILogger<PrescriptionModel>

Answer 1

Use the model to retrieve any data looks very bad in case of MVC pattern. A better way, if you don't want to touch controller - use code blocks in your view. for example:

@using Microsoft.AspNetCore.Identity

@inject SignInManager<IdentityUser> SignInManager
@inject UserManager<IdentityUser> UserManager
@{
    var usr = await UserManager.GetUserAsync(User);
    var email = usr?.Email;
}

After you can render variable in your view

<li class="email">
                <label asp-for="userEmail">@email</label>
                <input asp-for="userEmail" class="form-control" disabled />
</li>

The best way to get data to view is to assign it in controller and pass to the view in model.

If this way is not suitable for you - please explain and we can found right solution.

The best way, and how MVC implementation must work: All data came from controller with use of strongly typed Views:

 public class HomeController : Controller
    {
        private readonly UserManager<IdentityUser> _userManager;
        public HomeController (UserManager<IdentityUser> manager)
        {
            _userManager = manager;
        }
        public async Task<IActionResult> Index()
        {
            var usr =  await _userManager.GetUserAsync(HttpContext.User);
            return View(new UserModel { Email = usr?.Email });
        }

Where model is:

public class UserModel
    {
        public string Email { get; set; }
    }

So you just query all information that you need in the controller action/index and pass it to view with your model. This allow you to have different purpose files. Controller for data manipulatuion/businesss logic Model just DTO to pass values. View to render it. Check this to have more detailed information: https://docs.microsoft.com/en-us/aspnet/core/mvc/overview?view=aspnetcore-3.1