.NET Core RazorPages/MVCでユーザ登録ページをカスタマイズする方法

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Text.Encodings.Web;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI.Services;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.WebUtilities;
using HelloRazorProject.Models;
namespace HelloRazorProject.Areas.Identity.Pages.Account
{
　public class RegisterModel : PageModel
  {
    //IdentityUserをApplicationUserに書き換え
    private readonly SignInManager<ApplicationUser> _signInManager;
    private readonly UserManager<ApplicationUser> _userManager;
    private readonly IUserStore<ApplicationUser> _userStore;
    private readonly IUserEmailStore<ApplicationUser> _emailStore;
    private readonly ILogger<RegisterModel> _logger;
    private readonly IEmailSender _emailSender;

    //IdentityUserをApplicationUserに書き換え
　　public RegisterModel(
　　　　UserManager<ApplicationUser> userManager,
　　　　IUserStore<ApplicationUser> userStore,
　　　　SignInManager<ApplicationUser> signInManager,
　　　　ILogger<RegisterModel> logger,
　　　　IEmailSender emailSender)
　　{
　　　　_userManager = userManager;
　　　　_userStore = userStore;
　　　　_emailStore = GetEmailStore();
　　　　_signInManager = signInManager;
　　　　_logger = logger;
　　　　_emailSender = emailSender;
　　}
　　[BindProperty]
　　public InputModel Input { get; set; }
　　public string ReturnUrl { get; set; }

　　public IList<AuthenticationScheme> ExternalLogins { get; set; }

　　public class InputModel
　　{
　　　　[Required]
　　　　[EmailAddress]
　　　　[Display(Name = "Email")]
　　　　public string Email { get; set; }

　　　　[Required]
　　　　[StringLength(100, ErrorMessage = "The {0} must be at least {2} and at max {1} characters long.", MinimumLength = 6)]
　　　　[DataType(DataType.Password)]
　　　　[Display(Name = "Password")]
　　　　public string Password { get; set; }

　　　　[DataType(DataType.Password)]
　　　　[Display(Name = "Confirm password")]
　　　　[Compare("Password", ErrorMessage = "The password and confirmation password do not match.")]
　　　　public string ConfirmPassword { get; set; }
　　　　//以下の処理を追記
　　　　[Required]
　　　　public string Name { get; set; }
　　　　public int Age { get; set; }　　
　　} 
  }
}

@page
@model RegisterModel
@{
    ViewData["Title"] = "Register";
}
<h1>@ViewData["Title"]</h1>
<div class="row">
　 <div class="col-md-4">
    <form id="registerForm" asp-route-returnUrl="@Model.ReturnUrl" method="post">
      <h2>Create a new account.</h2>
      <hr />
      <div asp-validation-summary="ModelOnly" class="text-danger"></div>

      //---以下の処理を追記---
      <div class="form-floating">
          <input asp-for="Input.Name" class="form-control" autocomplete="username" aria-required="true" />
          <label asp-for="Input.Name"></label>
          <span asp-validation-for="Input.Name" class="text-danger"></span>
      </div>
      <div class="form-floating">
          <input asp-for="Input.Age" class="form-control" autocomplete="username" aria-required="true" />
          <label asp-for="Input.Age"></label>
          <span asp-validation-for="Input.Age" class="text-danger"></span>
      </div>
      //---ここまで---

      <div class="form-floating">
         <input asp-for="Input.Email" class="form-control" autocomplete="username" aria-required="true" />
         <label asp-for="Input.Email"></label>
         <span asp-validation-for="Input.Email" class="text-danger"></span>
      </div>
      <div class="form-floating">
          <input asp-for="Input.Password" class="form-control" autocomplete="new-password" aria-required="true" />
          <label asp-for="Input.Password"></label>
          <span asp-validation-for="Input.Password" class="text-danger"></span>
      </div>
      <div class="form-floating">
          <input asp-for="Input.ConfirmPassword" class="form-control" autocomplete="new-password" aria-required="true" />
          <label asp-for="Input.ConfirmPassword"></label>
          <span asp-validation-for="Input.ConfirmPassword" class="text-danger"></span>
      </div>
      <button id="registerSubmit" type="submit" class="w-100 btn btn-lg btn-primary">Register</button>
    </form>
  </div>
  <div class="col-md-6 col-md-offset-2">
    <section>
      <h3>Use another service to register.</h3>
      <hr />
      @{
        if ((Model.ExternalLogins?.Count ?? 0) == 0)
        {
          <div>
            <p>
              There are no external authentication services configured. See this <a href="https://go.microsoft.com/fwlink/?LinkID=532715">article
              about setting up this ASP.NET application to support logging in via external services</a>.
            </p>
          </div>
        }
        else
        {
          <form id="external-account" asp-page="./ExternalLogin" asp-route-returnUrl="@Model.ReturnUrl" method="post" class="form-horizontal">
            <div>
                <p>
                  @foreach (var provider in Model.ExternalLogins)
                  {
                    <button type="submit" class="btn btn-primary" name="provider" value="@provider.Name" title="Log in using your @provider.DisplayName account">@provider.DisplayName</button>
                  }
                </p>
            </div>
          </form>
        }
      }
    </section>
  </div>
</div>

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

using HelloRazorProject.Models;//using文を追加

//IdentityUserをApplicationUserに
builder.Services.AddDefaultIdentity<ApplicationUser>(options => options.SignIn.RequireConfirmedAccount = true)
　　.AddEntityFrameworkStores<ApplicationDbContext>();
//