ASP.NET Core：如何将C#类异常状态码传递至TypeScript客户端

步骤1：创建自定义异常类 #

替换系统自带的FormatException，定义专属异常类以便精准识别错误类型：

public class InvalidRepositoryUriException : Exception
{
    public InvalidRepositoryUriException(string message) : base(message)
    {
    }
}

步骤2：修改控制器抛出自定义异常 #

在控制器的检查逻辑中，抛出刚才定义的专属异常：

if (!repoUrlFormatMatch.Success)            
    throw new InvalidRepositoryUriException($"The repositoryUri '{repositoryUri}' did not conform to the expected format for an Azure Devops Git repository.");

步骤3：全局捕获异常并返回指定状态码 #

可以通过全局异常过滤器或异常处理中间件实现，以下提供两种可选方案：

方案A：使用全局异常过滤器

1. 实现异常过滤器类：

public class CustomExceptionFilter : IExceptionFilter
{
    public void OnException(ExceptionContext context)
    {
        if (context.Exception is InvalidRepositoryUriException invalidRepoUriEx)
        {
            // 返回400 Bad Request（也可根据业务需求选用422 Unprocessable Entity）
            context.Result = new ObjectResult(new { Message = invalidRepoUriEx.Message })
            {
                StatusCode = StatusCodes.Status400BadRequest
            };
            context.ExceptionHandled = true;
        }
        // 其他未捕获异常默认返回500状态码
    }
}

2. 在Program.cs（.NET 6+）中注册过滤器：

builder.Services.AddControllers(options =>
{
    options.Filters.Add<CustomExceptionFilter>();
});

方案B：使用异常处理中间件

在Program.cs中配置全局异常处理中间件：

app.UseExceptionHandler(errorApp =>
{
    errorApp.Run(async context =>
    {
        var exceptionFeature = context.Features.Get<IExceptionHandlerPathFeature>();
        var exception = exceptionFeature?.Error;

        if (exception is InvalidRepositoryUriException invalidRepoUriEx)
        {
            context.Response.StatusCode = StatusCodes.Status400BadRequest;
            context.Response.ContentType = "application/json";
            await context.Response.WriteAsJsonAsync(new { Message = invalidRepoUriEx.Message });
        }
        else
        {
            // 通用服务器错误返回500状态码
            context.Response.StatusCode = StatusCodes.Status500InternalServerError;
            context.Response.ContentType = "application/json";
            await context.Response.WriteAsJsonAsync(new { Message = "An unexpected error occurred." });
        }
    });
});

步骤4：客户端根据状态码处理提示 #

修改TypeScript代码，针对不同状态码展示对应提示信息：

const response = await fetch(`api/projectdecommissionrequest`, {
    body: JSON.stringify(postBody),
    headers: new Headers({
        "Accept": "application/json",
        "Authorization": `Bearer ${token}`,
        "Content-Type": "application/json",
    }),
    method: "POST",
});

if (response.ok) {
    console.log("Decommission request submitted successfully");
} else if (response.status === 400) {
    const error = await response.json();
    alert(`Error: ${error.Message}`);
} else if (response.status === 500) {
    alert("A server error occurred. Please try again later.");
} else {
    alert(`Request failed with status code: ${response.status}`);
}

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