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C# ASP.NET核心Web API异常处理

c# exception asp.net-core

C# ASP.NET核心Web API异常处理,c#,exception,asp.net-core,C#,Exception,Asp.net Core,在使用常规ASP.NETWebAPI多年后，我正在为我的新RESTAPI项目使用ASP.NETCore。在ASP.NET核心Web API中，我看不到任何处理异常的好方法。我尝试实现异常处理筛选器/属性： public class ErrorHandlingFilter : ExceptionFilterAttribute { public override void OnException(ExceptionContext context) { HandleEx

在使用常规ASP.NETWebAPI多年后，我正在为我的新RESTAPI项目使用ASP.NETCore。在ASP.NET核心Web API中，我看不到任何处理异常的好方法。我尝试实现异常处理筛选器/属性：

public class ErrorHandlingFilter : ExceptionFilterAttribute
{
    public override void OnException(ExceptionContext context)
    {
        HandleExceptionAsync(context);
        context.ExceptionHandled = true;
    }

    private static void HandleExceptionAsync(ExceptionContext context)
    {
        var exception = context.Exception;

        if (exception is MyNotFoundException)
            SetExceptionResult(context, exception, HttpStatusCode.NotFound);
        else if (exception is MyUnauthorizedException)
            SetExceptionResult(context, exception, HttpStatusCode.Unauthorized);
        else if (exception is MyException)
            SetExceptionResult(context, exception, HttpStatusCode.BadRequest);
        else
            SetExceptionResult(context, exception, HttpStatusCode.InternalServerError);
    }

    private static void SetExceptionResult(
        ExceptionContext context, 
        Exception exception, 
        HttpStatusCode code)
    {
        context.Result = new JsonResult(new ApiResponse(exception))
        {
            StatusCode = (int)code
        };
    }
}
这是我的启动过滤器注册：

services.AddMvc(options =>
{
    options.Filters.Add(new AuthorizationFilter());
    options.Filters.Add(new ErrorHandlingFilter());
});
我遇到的问题是，当我的
AuthorizationFilter
中发生异常时，它不是由
ErrorHandlingFilter
处理的。我希望它能像使用旧的ASP.NETWebAPI一样在那里被捕获

那么，如何捕获所有应用程序异常以及操作筛选器中的任何异常呢？

您最好的选择是使用中间件来实现所需的日志记录。您希望将异常日志记录放在一个中间件中，然后在另一个中间件中处理显示给用户的错误页面。这允许逻辑分离，并遵循微软用两个中间件组件设计的设计。以下是指向Microsoft文档的良好链接：

对于您的特定示例，您可能希望使用中的一个扩展，或者自己使用

您可以在此处找到记录异常的示例：

如果您不喜欢特定的实现，那么您也可以使用，下面是一些示例：

如果这不符合您的需要，您可以通过查看ExceptionHandlerMiddleware和ElmMiddleware的实现来滚动自己的中间件组件，以掌握构建自己的中间件的概念

在StatusCodePages中间件下面添加异常处理中间件，但在所有其他中间件组件之上，这一点很重要。这样，您的异常中间件将捕获异常，记录它，然后允许请求进入StatusCodePage中间件，该中间件将向用户显示友好的错误页面。

两种方法都使用内置的异常处理中间件。在调用
UseMvc
、
UseRouting
或
UseEndpoints
之前添加此代码。它将处理所有注册后的中间件的例外情况

快速简便的解决方案。 只需在ASP.NET路由之前将此中间件添加到中间件注册中即可

app.UseExceptionHandler(c => c.Run(async context =>
{
    var exception = context.Features
        .Get<IExceptionHandlerPathFeature>()
        .Error;
    var response = new { error = exception.Message };
    await context.Response.WriteAsJsonAsync(response);
}));
步骤2。创建将处理所有异常并产生错误响应的控制器：

[AllowAnonymous]
[ApiExplorerSettings(IgnoreApi = true)]
public class ErrorsController : ControllerBase
{
    [Route("error")]
    public MyErrorResponse Error()
    {
        var context = HttpContext.Features.Get<IExceptionHandlerFeature>();
        var exception = context.Error; // Your exception
        var code = 500; // Internal Server Error by default

        if      (exception is MyNotFoundException) code = 404; // Not Found
        else if (exception is MyUnauthException)   code = 401; // Unauthorized
        else if (exception is MyException)         code = 400; // Bad Request

        Response.StatusCode = code; // You can use HttpStatusCode enum instead

        return new MyErrorResponse(exception); // Your error model
    }
}
对于更简单的服务，您可能希望实现如下所示的http状态代码异常：

public class HttpStatusException : Exception
{
    public HttpStatusCode Status { get; private set; }

    public HttpStatusException(HttpStatusCode status, string msg) : base(msg)
    {
        Status = status;
    }
}

using System;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Hosting;

namespace Api.Controllers
{
    [ApiController]
    [ApiExplorerSettings(IgnoreApi = true)]
    [AllowAnonymous]
    public class ErrorController : ControllerBase
    {
        [Route("/error")]
        public IActionResult Error(
            [FromServices] IWebHostEnvironment webHostEnvironment)
        {
            var context = HttpContext.Features.Get<IExceptionHandlerFeature>();
            var exceptionType = context.Error.GetType();
            
            if (exceptionType == typeof(ArgumentException)
                || exceptionType == typeof(ArgumentNullException)
                || exceptionType == typeof(ArgumentOutOfRangeException))
            {
                if (webHostEnvironment.IsDevelopment())
                {
                    return ValidationProblem(
                        context.Error.StackTrace,
                        title: context.Error.Message);
                }

                return ValidationProblem(context.Error.Message);
            }

            if (exceptionType == typeof(NotFoundException))
            {
                return NotFound(context.Error.Message);
            }

            if (webHostEnvironment.IsDevelopment())
            {
                return Problem(
                    context.Error.StackTrace,
                    title: context.Error.Message
                    );
            }
            
            return Problem();
        }
    }
}
这可以通过以下方式从任何地方抛出：

throw new HttpStatusCodeException(HttpStatusCode.NotFound, "User not found");
然后，您的处理代码可以简化为：

if (exception is HttpStatusException httpException)
{
    code = (int) httpException.Status;
}

HttpContext.Features.Get（）
WAT

ASP.NET核心开发人员接受了中间件的概念，在中间件中，Auth、MVC、Swagger等功能的不同方面被分离，并在请求处理管道中顺序执行。每个中间件都可以访问请求上下文，并可以在需要时写入响应。如果像处理MVC异常一样处理来自非MVC中间件的错误很重要，那么将异常处理从MVC中去掉是有意义的，我发现这在现实世界的应用程序中非常常见。因此，由于内置的异常处理中间件不是MVC的一部分，MVC本身对它一无所知，反之亦然，异常处理中间件并不真正知道异常来自何处，而且它当然知道异常发生在请求执行过程中的某个地方。但两者可能都需要相互“连接”。所以，当异常在任何地方都没有被捕获时，异常处理中间件会捕获它，并重新运行在其中注册的路由的管道。这就是使用consistent或其他中间件（如果您愿意）将异常处理“传递”回MVC的方式。异常本身是从公共中间件上下文中提取的。看起来很有趣，但完成了任务：）。

首先，配置ASP.NET Core 2
启动
以重新执行到错误页，查找web服务器的任何错误和任何未处理的异常

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment()) {
        // Debug config here...
    } else {
        app.UseStatusCodePagesWithReExecute("/Error");
        app.UseExceptionHandler("/Error");
    }
    // More config...
}
接下来，定义一个异常类型，该类型将允许您使用HTTP状态代码抛出错误

public class HttpException : Exception
{
    public HttpException(HttpStatusCode statusCode) { StatusCode = statusCode; }
    public HttpStatusCode StatusCode { get; private set; }
}
最后，在控制器的错误页面中，根据错误原因以及最终用户是否会直接看到响应来定制响应。此代码假定所有API URL都以
/API/
开头

[AllowAnonymous]
public IActionResult Error()
{
    // Gets the status code from the exception or web server.
    var statusCode = HttpContext.Features.Get<IExceptionHandlerFeature>()?.Error is HttpException httpEx ?
        httpEx.StatusCode : (HttpStatusCode)Response.StatusCode;

    // For API errors, responds with just the status code (no page).
    if (HttpContext.Features.Get<IHttpRequestFeature>().RawTarget.StartsWith("/api/", StringComparison.Ordinal))
        return StatusCode((int)statusCode);

    // Creates a view model for a user-friendly error page.
    string text = null;
    switch (statusCode) {
        case HttpStatusCode.NotFound: text = "Page not found."; break;
        // Add more as desired.
    }
    return View("Error", new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier, ErrorText = text });
}

[AllowAnonymous]
公共IActionResult错误（）
{
//从异常或web服务器获取状态代码。
var statusCode=HttpContext.Features.Get（）？。错误为HttpException httpEx？
httpEx.StatusCode：（HttpStatusCode）Response.StatusCode；
//对于API错误，只响应状态代码（无页面）。
if（HttpContext.Features.Get（）.RawTarget.StartsWith（“/api/”，StringComparison.Ordinal））
返回状态码（（int）状态码）；
//为用户友好的错误页面创建视图模型。
字符串文本=空；
开关（状态代码）{
案例HttpStatusCode.NotFound:text=“未找到页面。”中断；
//根据需要添加更多。
}
返回视图（“错误”，新的ErrorViewModel{RequestId=Activity.Current？.Id？？HttpContext.TraceIdentifier，ErrorText=text}）；
}
ASP.NET Core将记录错误详细信息供您调试，因此状态代码可能是您希望向（可能不受信任的）请求者提供的所有代码。如果您想显示更多信息，可以增强
HttpException
来提供它。对于API错误，您可以通过将
返回状态码…
替换为
返回JSON…
，将JSON编码的错误信息放入消息正文中。要配置每种异常类型的异常处理行为，您可以使用NuGet包中的中间件：

  • 对于
    ASP.NET Core 2.0
  • 对于
    ASP.NET Core 2.1+
代码示例：

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();

    services.AddExceptionHandlingPolicies(options =>
    {
        options.For<InitializationException>().Rethrow();

        options.For<SomeTransientException>().Retry(ro => ro.MaxRetryCount = 2).NextPolicy();

        options.For<SomeBadRequestException>()
        .Response(e => 400)
            .Headers((h, e) => h["X-MyCustomHeader"] = e.Message)
            .WithBody((req,sw, exception) =>
                {
                    byte[] array = Encoding.UTF8.GetBytes(exception.ToString());
                    return sw.WriteAsync(array, 0, array.Length);
                })
        .NextPolicy();

        // Ensure that all exception types are handled by adding handler for generic exception at the end.
        options.For<Exception>()
        .Log(lo =>
            {
                lo.EventIdFactory = (c, e) => new EventId(123, "UnhandlerException");
                lo.Category = (context, exception) => "MyCategory";
            })
        .Response(null, ResponseAlreadyStartedBehaviour.GoToNextHandler)
            .ClearCacheHeaders()
            .WithObjectResult((r, e) => new { msg = e.Message, path = r.Path })
        .Handled();
    });
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseExceptionHandlingPolicies();
    app.UseMvc();
}

public void配置服务（IServiceCollection服务）
{
services.AddMvc（）；
服务.AddExceptionHandlingPolicys（选项=>
{

public class HttpException : Exception
{
    public HttpException(HttpStatusCode statusCode) { StatusCode = statusCode; }
    public HttpStatusCode StatusCode { get; private set; }
}



[AllowAnonymous]
public IActionResult Error()
{
    // Gets the status code from the exception or web server.
    var statusCode = HttpContext.Features.Get<IExceptionHandlerFeature>()?.Error is HttpException httpEx ?
        httpEx.StatusCode : (HttpStatusCode)Response.StatusCode;

    // For API errors, responds with just the status code (no page).
    if (HttpContext.Features.Get<IHttpRequestFeature>().RawTarget.StartsWith("/api/", StringComparison.Ordinal))
        return StatusCode((int)statusCode);

    // Creates a view model for a user-friendly error page.
    string text = null;
    switch (statusCode) {
        case HttpStatusCode.NotFound: text = "Page not found."; break;
        // Add more as desired.
    }
    return View("Error", new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier, ErrorText = text });
}



public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();

    services.AddExceptionHandlingPolicies(options =>
    {
        options.For<InitializationException>().Rethrow();

        options.For<SomeTransientException>().Retry(ro => ro.MaxRetryCount = 2).NextPolicy();

        options.For<SomeBadRequestException>()
        .Response(e => 400)
            .Headers((h, e) => h["X-MyCustomHeader"] = e.Message)
            .WithBody((req,sw, exception) =>
                {
                    byte[] array = Encoding.UTF8.GetBytes(exception.ToString());
                    return sw.WriteAsync(array, 0, array.Length);
                })
        .NextPolicy();

        // Ensure that all exception types are handled by adding handler for generic exception at the end.
        options.For<Exception>()
        .Log(lo =>
            {
                lo.EventIdFactory = (c, e) => new EventId(123, "UnhandlerException");
                lo.Category = (context, exception) => "MyCategory";
            })
        .Response(null, ResponseAlreadyStartedBehaviour.GoToNextHandler)
            .ClearCacheHeaders()
            .WithObjectResult((r, e) => new { msg = e.Message, path = r.Path })
        .Handled();
    });
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseExceptionHandlingPolicies();
    app.UseMvc();
}



public class ExceptionHandlerMiddleware
{
    private readonly RequestDelegate next;
    private readonly IActionResultExecutor<ObjectResult> executor;
    private readonly ILogger logger;
    private static readonly ActionDescriptor EmptyActionDescriptor = new ActionDescriptor();

    public ExceptionHandlerMiddleware(RequestDelegate next, IActionResultExecutor<ObjectResult> executor, ILoggerFactory loggerFactory)
    {
        this.next = next;
        this.executor = executor;
        logger = loggerFactory.CreateLogger<ExceptionHandlerMiddleware>();
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            await next(context);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, $"An unhandled exception has occurred while executing the request. Url: {context.Request.GetDisplayUrl()}. Request Data: " + GetRequestData(context));

            if (context.Response.HasStarted)
            {
                throw;
            }

            var routeData = context.GetRouteData() ?? new RouteData();

            ClearCacheHeaders(context.Response);

            var actionContext = new ActionContext(context, routeData, EmptyActionDescriptor);

            var result = new ObjectResult(new ErrorResponse("Error processing request. Server error."))
            {
                StatusCode = (int) HttpStatusCode.InternalServerError,
            };

            await executor.ExecuteAsync(actionContext, result);
        }
    }

    private static string GetRequestData(HttpContext context)
    {
        var sb = new StringBuilder();

        if (context.Request.HasFormContentType && context.Request.Form.Any())
        {
            sb.Append("Form variables:");
            foreach (var x in context.Request.Form)
            {
                sb.AppendFormat("Key={0}, Value={1}<br/>", x.Key, x.Value);
            }
        }

        sb.AppendLine("Method: " + context.Request.Method);

        return sb.ToString();
    }

    private static void ClearCacheHeaders(HttpResponse response)
    {
        response.Headers[HeaderNames.CacheControl] = "no-cache";
        response.Headers[HeaderNames.Pragma] = "no-cache";
        response.Headers[HeaderNames.Expires] = "-1";
        response.Headers.Remove(HeaderNames.ETag);
    }

    [DataContract(Name= "ErrorResponse")]
    public class ErrorResponse
    {
        [DataMember(Name = "Message")]
        public string Message { get; set; }

        public ErrorResponse(string message)
        {
            Message = message;
        }
    }
}



public class ErrorDetails
{
    public int StatusCode { get; set; }
    public string Message { get; set; }

    public override string ToString()
    {
        return JsonConvert.SerializeObject(this);
    }
}



public class HttpStatusCodeException : Exception
{
    public HttpStatusCode StatusCode { get; set; }
    public string ContentType { get; set; } = @"text/plain";

    public HttpStatusCodeException(HttpStatusCode statusCode)
    {
        this.StatusCode = statusCode;
    }

    public HttpStatusCodeException(HttpStatusCode statusCode, string message) 
        : base(message)
    {
        this.StatusCode = statusCode;
    }

    public HttpStatusCodeException(HttpStatusCode statusCode, Exception inner) 
        : this(statusCode, inner.ToString()) { }

    public HttpStatusCodeException(HttpStatusCode statusCode, JObject errorObject) 
        : this(statusCode, errorObject.ToString())
    {
        this.ContentType = @"application/json";
    }

}



public class CustomExceptionMiddleware
{
    private readonly RequestDelegate next;

    public CustomExceptionMiddleware(RequestDelegate next)
    {
        this.next = next;
    }

    public async Task Invoke(HttpContext context /* other dependencies */)
    {
        try
        {
            await next(context);
        }
        catch (HttpStatusCodeException ex)
        {
            await HandleExceptionAsync(context, ex);
        }
        catch (Exception exceptionObj)
        {
            await HandleExceptionAsync(context, exceptionObj);
        }
    }

    private Task HandleExceptionAsync(HttpContext context, HttpStatusCodeException exception)
    {
        string result = null;
        context.Response.ContentType = "application/json";
        if (exception is HttpStatusCodeException)
        {
            result = new ErrorDetails() 
            {
                Message = exception.Message,
                StatusCode = (int)exception.StatusCode 
            }.ToString();
            context.Response.StatusCode = (int)exception.StatusCode;
        }
        else
        {
            result = new ErrorDetails() 
            { 
                Message = "Runtime Error",
                StatusCode = (int)HttpStatusCode.BadRequest
            }.ToString();
            context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
        }
        return context.Response.WriteAsync(result);
    }

    private Task HandleExceptionAsync(HttpContext context, Exception exception)
    {
        string result = new ErrorDetails() 
        { 
            Message = exception.Message,
            StatusCode = (int)HttpStatusCode.InternalServerError 
        }.ToString();
        context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
        return context.Response.WriteAsync(result);
    }
}



public static void ConfigureCustomExceptionMiddleware(this IApplicationBuilder app)
{
    app.UseMiddleware<CustomExceptionMiddleware>();
}



app.ConfigureCustomExceptionMiddleware();
app.UseMvc();



try
{
    IRepository<UserMaster> obj 
        = new Repository<UserMaster>(_objHeaderCapture, Constants.Tables.UserMaster);
    var result = obj.Get()
        .AsQueryable()
        .Where(sb => sb.EmailId.ToLower() == objData.UserName.ToLower() 
            && sb.Password == objData.Password.ToEncrypt() 
            && sb.Status == (int)StatusType.Active)
        .FirstOrDefault();
    if (result != null)//User Found
        return result;
    else // Not Found
        throw new HttpStatusCodeException(HttpStatusCode.NotFound,
            "Please check username or password");
}
catch (Exception ex)
{
    throw ex;
}



app.UseExceptionHandler(a => a.Run(async context =>
{
    var exceptionHandlerPathFeature = context.Features.Get<IExceptionHandlerPathFeature>();
    var exception = exceptionHandlerPathFeature.Error;
    
    await context.Response.WriteAsJsonAsync(new { error = exception.Message });
}));



app.UseExceptionHandler(a => a.Run(async context =>
{
    var exceptionHandlerPathFeature = context.Features.Get<IExceptionHandlerPathFeature>();
    var exception = exceptionHandlerPathFeature.Error;
    
    var result = JsonConvert.SerializeObject(new { error = exception.Message });
    context.Response.ContentType = "application/json";
    await context.Response.WriteAsync(result);
}));



public class HttpGlobalExceptionFilter : IExceptionFilter
{
  public void OnException(ExceptionContext context)
  {...}
}



services.AddMvc(options =>
{
  options.Filters.Add(typeof(HttpGlobalExceptionFilter));
})



app.UseExceptionHandler("/error");



using System;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Hosting;

namespace Api.Controllers
{
    [ApiController]
    [ApiExplorerSettings(IgnoreApi = true)]
    [AllowAnonymous]
    public class ErrorController : ControllerBase
    {
        [Route("/error")]
        public IActionResult Error(
            [FromServices] IWebHostEnvironment webHostEnvironment)
        {
            var context = HttpContext.Features.Get<IExceptionHandlerFeature>();
            var exceptionType = context.Error.GetType();
            
            if (exceptionType == typeof(ArgumentException)
                || exceptionType == typeof(ArgumentNullException)
                || exceptionType == typeof(ArgumentOutOfRangeException))
            {
                if (webHostEnvironment.IsDevelopment())
                {
                    return ValidationProblem(
                        context.Error.StackTrace,
                        title: context.Error.Message);
                }

                return ValidationProblem(context.Error.Message);
            }

            if (exceptionType == typeof(NotFoundException))
            {
                return NotFound(context.Error.Message);
            }

            if (webHostEnvironment.IsDevelopment())
            {
                return Problem(
                    context.Error.StackTrace,
                    title: context.Error.Message
                    );
            }
            
            return Problem();
        }
    }
}



using Microsoft.AspNetCore.Http;
...

public ActionResult MyAPIMethod()
{
    try
    {
       var myObject = ... something;

       return Json(myObject);
    }
    catch (Exception ex)
    {
        Log.Error($"Error: {ex.Message}");
        return StatusCode(StatusCodes.Status500InternalServerError);
    }         
}



    private static readonly Type[] API_CATCH_EXCEPTIONS = new Type[]
    {
        typeof(InvalidOperationException),
        typeof(ValidationException)           
    };

    public override void OnActionExecuted(ActionExecutedContext context)
    {
        base.OnActionExecuted(context);

        if (context.Exception != null)
        {
            var exType = context.Exception.GetType();
            if (API_CATCH_EXCEPTIONS.Any(type => exType == type || exType.IsSubclassOf(type)))
            {
                context.Result = Problem(detail: context.Exception.Message);
                context.ExceptionHandled = true;
            }
        }  
    }



public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    ...

    app.UseExceptionHandler(a => a.Run(async context =>
    {
        var error = context.Features.Get<IExceptionHandlerFeature>().Error;
        var problem = new ProblemDetails { Title = "Critical Error"};
        if (error != null)
        {
            if (env.IsDevelopment())
            {
                problem.Title = error.Message;
                problem.Detail = error.StackTrace;
            }
            else
                problem.Detail = error.Message;
        }
        await context.Response.WriteAsJsonAsync(problem);
    }));
    ...
}