ASP.Net Core 7.0 MVC全局错误处理：ErrorViewModel的OnGet/OnPost未触发

问题根源 #

你混淆了MVC控制器视图和Razor Page的实现逻辑：

• 配置app.UseExceptionHandler("/Home/Error")是指向MVC控制器的Action，而非Razor Page
• 让ErrorViewModel继承PageModel并添加OnGet/OnPost方法是Razor Page的写法，和MVC的视图模型逻辑不匹配
• 添加@page会把视图转为Razor Page，脱离MVC控制器的上下文，导致ViewData失效

修复步骤 #

1. 还原ErrorViewModel为普通MVC视图模型 #

删除PageModel继承、OnGet/OnPost方法以及Razor Page相关特性：

public class ErrorViewModel
{
    public string? RequestId { get; set; }
    public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
    // 新增异常信息属性
    public Exception? Exception { get; set; }
    public string? ExceptionMessage { get; set; }
}

2. 修改HomeController的Error Action获取异常信息 #

在HomeController中添加Error方法，通过IExceptionHandlerPathFeature捕获未处理的异常：

using Microsoft.AspNetCore.Diagnostics;

public class HomeController : Controller
{
    // ... 其他方法

    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
    [IgnoreAntiforgeryToken]
    public IActionResult Error()
    {
        // 获取异常处理特性
        var exceptionFeature = HttpContext.Features.Get<IExceptionHandlerPathFeature>();
        
        var viewModel = new ErrorViewModel
        {
            RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier,
            Exception = exceptionFeature?.Error,
            ExceptionMessage = exceptionFeature?.Error?.Message
        };

        return View(viewModel);
    }
}

3. 确保Program.cs的中间件顺序正确 #

中间件顺序会影响错误处理逻辑，确保UseExceptionHandler在UseRouting和UseAuthorization之前：

var builder = WebApplication.CreateBuilder(args);

// 添加服务
builder.Services.AddControllersWithViews();

var app = builder.Build();

// 全局错误处理中间件（必须在路由之前）
app.UseExceptionHandler("/Home/Error");
app.UseHsts();

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

app.Run();

4. 调整Shared/Error.cshtml视图 #

移除@page指令，确保视图绑定到ErrorViewModel并展示异常信息：

@model ErrorViewModel

@{
    ViewData["Title"] = "Error";
}

<h1 class="text-danger">Error.</h1>
<h2 class="text-danger">An error occurred while processing your request.</h2>

@if (Model.Exception != null)
{
    <div class="alert alert-danger">
        <h3>Exception Details:</h3>
        <p>@Model.ExceptionMessage</p>
        @if (!string.IsNullOrEmpty(Model.RequestId))
        {
            <p>Request ID: <code>@Model.RequestId</code></p>
        }
    </div>
}

<p>If you are unable to resolve this error, please contact the support team.</p>

测试验证 #

在HomeController的Index方法中抛出异常测试：

[HttpGet]
public IActionResult Index()
{
    throw new ApplicationException("测试全局错误处理");
}

运行项目后访问首页，会自动跳转到错误页并展示异常信息。

内容的提问来源于stack exchange，提问作者Rob K.