ASP.NET Core Identity フレームワークでユーザー名を更新する

Identity フレームワークでは、デフォルトの状態ではユーザー名に対する更新(変更)機能は実装されていません。次のように変更を行うことで、ユーザー名を更新することができます。

なお、ファイルは Areas\Identity\Pages\Account\Manage フォルダ配下にあります。

※ 変更点はハイライトしています。

Index.cshtml

@page
@model IndexModel
@{
    ViewData["Title"] = "Profile";
    ViewData["ActivePage"] = ManageNavPages.Index;
}

<h4>@ViewData["Title"]</h4>
<partial name="_StatusMessage" model="Model.StatusMessage" />
<div class="row">
    <div class="col-md-6">
        <form id="profile-form" method="post">
            <div asp-validation-summary="All" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="Input.UserName"></label>						<!--変更-->
                <input asp-for="Input.UserName" class="form-control" />		<!--変更-->
            </div>
            <div class="form-group">
                <label asp-for="Input.PhoneNumber"></label>
                <input asp-for="Input.PhoneNumber" class="form-control" />
                <span asp-validation-for="Input.PhoneNumber" class="text-danger"></span>
            </div>
            <button id="update-profile-button" type="submit" class="btn btn-primary">Save</button>
        </form>
    </div>
</div>

@section Scripts {
    <partial name="_ValidationScriptsPartial" />
}

Index.cshtml.cs

namespace App.Areas.Identity.Pages.Account.Manage
{
    public partial class IndexModel : PageModel
    {
        private readonly UserManager<IdentityUser> _userManager;
        private readonly SignInManager<IdentityUser> _signInManager;

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

        public string Username { get; set; }

        [TempData]
        public string StatusMessage { get; set; }

        [BindProperty]
        public InputModel Input { get; set; }

        public class InputModel
        {
            [Display(Name = "User name")]				// 追加
            public string UserName { get; set; }	// 追加
            [Phone]
            [Display(Name = "Phone number")]
            public string PhoneNumber { get; set; }
        }

        private async Task LoadAsync(IdentityUser user)
        {
            var userName = await _userManager.GetUserNameAsync(user);
            var phoneNumber = await _userManager.GetPhoneNumberAsync(user);

            //Username = userName;		// 削除

            Input = new InputModel
            {
                UserName = userName,	// 追加
                PhoneNumber = phoneNumber
            };
        }

        public async Task<IActionResult> OnGetAsync()
        {
            var user = await _userManager.GetUserAsync(User);
            if (user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }

            await LoadAsync(user);
            return Page();
        }

        public async Task<IActionResult> OnPostAsync()
        {
            var user = await _userManager.GetUserAsync(User);
            if (user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }

            if (!ModelState.IsValid)
            {
                await LoadAsync(user);
                return Page();
            }
					// 追加ここから
            var userName = await _userManager.GetUserNameAsync(user);
            if (Input.UserName != userName)
            {
                var setUserNameResult = await _userManager.SetUserNameAsync(user, Input.UserName);
                if (!setUserNameResult.Succeeded)
                {
                    var userId = await _userManager.GetUserIdAsync(user);
                    throw new InvalidOperationException($"Unexpected error occurred setting user name for user with ID '{userId}'.");
                }
            }
					// 追加ここまで
            var phoneNumber = await _userManager.GetPhoneNumberAsync(user);
            if (Input.PhoneNumber != phoneNumber)
            {
                var setPhoneResult = await _userManager.SetPhoneNumberAsync(user, Input.PhoneNumber);
                if (!setPhoneResult.Succeeded)
                {
                    var userId = await _userManager.GetUserIdAsync(user);
                    throw new InvalidOperationException($"Unexpected error occurred setting phone number for user with ID '{userId}'.");
                }
            }

            await _signInManager.RefreshSignInAsync(user);
            StatusMessage = "Your profile has been updated";
            return RedirectToPage();
        }
    }
}