.NET 8 Blazor Server认证后：手动登录切换、登出及数据存储问题

在Blazor组件中注入NavigationManager和IAuthenticationService，通过触发认证挑战跳转至Microsoft登录页：

@inject NavigationManager NavManager
@inject IAuthenticationService AuthService
@using Microsoft.AspNetCore.Authentication.OpenIdConnect

<button @onclick="SwitchUser">切换用户</button>

@code {
    private async Task SwitchUser()
    {
        await AuthService.ChallengeAsync(OpenIdConnectDefaults.AuthenticationScheme, 
            new AuthenticationProperties
            {
                RedirectUri = NavManager.Uri // 登录后返回当前页面
            });
    }
}

实现登出功能 #

在组件中注入服务，同时注销本地会话和Azure AD会话：

@inject NavigationManager NavManager
@inject IAuthenticationService AuthService
@using Microsoft.AspNetCore.Authentication.Cookies

<button @onclick="Logout">登出</button>

@code {
    private async Task Logout()
    {
        var authProperties = new AuthenticationProperties
        {
            RedirectUri = NavManager.BaseUri // 登出后返回首页
        };
        // 同时清除本地Cookie和Azure AD端会话
        await AuthService.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme, authProperties);
        await AuthService.SignOutAsync(OpenIdConnectDefaults.AuthenticationScheme, authProperties);
    }
}

解决调试后残留登录状态的问题 #

1. 在Program.cs中配置登出回调：

builder.Services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
    .AddMicrosoftIdentityWebApp(builder.Configuration.GetSection("AzureAd"), options =>
    {
        options.Events.OnRedirectToIdentityProviderForSignOut = context =>
        {
            context.PostLogoutRedirectUri = builder.Configuration["AzureAd:PostLogoutRedirectUri"] ?? context.PostLogoutRedirectUri;
            return Task.CompletedTask;
        };
    });

在appsettings.json中补充配置：

"AzureAd": {
    // 原有配置...
    "PostLogoutRedirectUri": "https://localhost:xxxx/"
}

2. 登录Azure AD应用注册后台，在认证页面设置注销URL为上述地址，确保Azure AD端彻底清除会话。
3. 调试时若仍有残留，可清除浏览器Cookie或使用隐私窗口测试。

通过Scoped服务存储用户数据，在用户首次登录时加载，避免重复查询：

1. 创建用户数据存储服务 #

public class UserDataService
{
    public UserProfile? CurrentUser { get; set; }
    public bool IsDataLoaded => CurrentUser != null;
}

// 在Program.cs中注册为Scoped服务
builder.Services.AddScoped<UserDataService>();

2. 在MainLayout中监听认证状态并加载数据 #

@inject AuthenticationStateProvider AuthStateProvider
@inject UserDataService UserDataService
@inject YourDbContext DbContext

@code {
    protected override async Task OnInitializedAsync()
    {
        var authState = await AuthStateProvider.GetAuthenticationStateAsync();
        var user = authState.User;
        
        if (user.Identity?.IsAuthenticated == true && !UserDataService.IsDataLoaded)
        {
            // 从数据库查询用户数据（示例：通过用户名匹配）
            var userName = user.Identity.Name;
            var userProfile = await DbContext.UserProfiles.FirstOrDefaultAsync(u => u.UserName == userName);
            
            UserDataService.CurrentUser = userProfile;
        }

        // 监听认证状态变化，处理切换用户或登出场景
        AuthStateProvider.AuthenticationStateChanged += async state =>
        {
            var newUser = (await state).User;
            if (newUser.Identity?.IsAuthenticated == true && !UserDataService.IsDataLoaded)
            {
                var userName = newUser.Identity.Name;
                var userProfile = await DbContext.UserProfiles.FirstOrDefaultAsync(u => u.UserName == userName);
                UserDataService.CurrentUser = userProfile;
            }
            else if (!newUser.Identity?.IsAuthenticated ?? false)
            {
                UserDataService.CurrentUser = null;
            }
        };
    }
}

后续在任意组件中注入UserDataService，即可直接获取已缓存的用户数据，无需每次刷新重新查询。

内容的提问来源于stack exchange，提问作者Panthesilea