【C#、Blazor】Webアプリ開発入門編（Ex4）Azure AD B2C ～アプリへ簡単・多機能なユーザ認証を追加！～【ASP.NET Core】

dotnet new blazor -n BlazorAzureADB2CApp1 -o BlazorAzureADB2CApp1 -f net8.0 --interactivity Server

dotnet add package Microsoft.Identity.Web
dotnet add package Microsoft.Identity.Web.UI

using BlazorAzureADB2CApp1.Components;
using Microsoft.AspNetCore.Authentication.OpenIdConnect;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc.Authorization;
using Microsoft.Identity.Web;
using Microsoft.Identity.Web.UI;

var builder = WebApplication.CreateBuilder(args);

//★(a) Configure Azure AD B2C Authentication using OpenID Connect
builder.Services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
    .AddMicrosoftIdentityWebApp(builder.Configuration.GetSection("AzureAdB2C"))
    .EnableTokenAcquisitionToCallDownstreamApi()
    .AddInMemoryTokenCaches();

//★(b) Add authorization policy requiring authentication for all controllers
builder.Services.AddControllersWithViews(options =>
{
    var policy = new AuthorizationPolicyBuilder()
        .RequireAuthenticatedUser()
        .Build();
    options.Filters.Add(new AuthorizeFilter(policy));
});

//★(c) Add Razor Pages and Microsoft Identity UI for authentication-related pages
builder.Services.AddRazorPages()
    .AddMicrosoftIdentityUI();

// Add services to the container.
builder.Services.AddRazorComponents()
    .AddInteractiveServerComponents();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error", createScopeForErrors: true);
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();

app.UseStaticFiles();
app.UseAntiforgery();

app.MapRazorComponents<App>()
    .AddInteractiveServerRenderMode();

//★(d) Enable routing for authentication-related UI pages
app.MapControllers();
app.MapRazorPages();

app.Run();

<div class="top-row ps-3 navbar navbar-dark">
    <div class="container-fluid">
        <a class="navbar-brand" href="">BlazorAzureADB2CApp1</a>
    </div>
</div>

<input type="checkbox" title="Navigation menu" class="navbar-toggler" />

<div class="nav-scrollable" onclick="document.querySelector('.navbar-toggler').click()">
    <nav class="flex-column">
        <div class="nav-item px-3">
            <NavLink class="nav-link" href="" Match="NavLinkMatch.All">
                <span class="bi bi-house-door-fill-nav-menu" aria-hidden="true"></span> Home
            </NavLink>
        </div>

        <div class="nav-item px-3">
            <NavLink class="nav-link" href="counter">
                <span class="bi bi-plus-square-fill-nav-menu" aria-hidden="true"></span> Counter
            </NavLink>
        </div>

        <div class="nav-item px-3">
            <NavLink class="nav-link" href="weather">
                <span class="bi bi-list-nested-nav-menu" aria-hidden="true"></span> Weather
            </NavLink>
        </div>

        @*★(a)*@
        <div class="nav-item px-3">
            <a href="MicrosoftIdentity/Account/SignIn" class="nav-link">Login</a>
        </div>

        @*★(b)*@
        <div class="nav-item px-3">
            <a href="MicrosoftIdentity/Account/SignOut" class="nav-link">Logout</a>
        </div> 
    </nav>
</div>

@page "/"
@using Microsoft.AspNetCore.Components.Authorization
@using System.Security.Claims
@inject AuthenticationStateProvider AuthenticationStateProvider

<PageTitle>Home</PageTitle>

<h1>Hello, @UserName!</h1>
<p>Welcome to your new app.</p>

@code {
    private string UserName { get; set; } = "Guest";

    protected override async Task OnInitializedAsync()
    {
        var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
        var user = authState.User;

        if (user.Identity?.IsAuthenticated == true)
        {
            //★(a)
            var givenName = user.FindFirst(ClaimTypes.GivenName)?.Value ?? string.Empty;
            var surname = user.FindFirst(ClaimTypes.Surname)?.Value ?? string.Empty;
            UserName = $"{givenName} {surname}".Trim();
        }
    }
}

{
  //★(a)
  "AzureAdB2C": {
    "Instance": "https://【★(b)ドメイン名】.b2clogin.com",
    "Domain": "【★(b)ドメイン名】.onmicrosoft.com",
    "ClientId": "★(c)クライアントID",
    "SignUpSignInPolicyId": "★(d)ユーザフロー名",
    "ClientSecret": "★(e)クライアントシークレット",
    "ResponseType": "code"  // 認可コードフローを使う
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*"
}

  …
      "https": {
        "commandName": "Project",
        "dotnetRunMessages": true,
        "launchBrowser": true,
        "applicationUrl": "https://localhost:5001;http://localhost:5107", //★(a)
        "environmentVariables": {
          "ASPNETCORE_ENVIRONMENT": "Development"
        }
 …