C# WebAPI筛选器的ActionExecuteContext中的异常属性为null

我已经使用同一个异常过滤器好几个月了，到目前为止，它的性能非常好。这是：

public class HttpResponseExceptionFilter : IActionFilter, IOrderedFilter
{
    public int Order { get; set; } = int.MaxValue - 10;

    public void OnActionExecuting(ActionExecutingContext context)
    {
    }

    public void OnActionExecuted(ActionExecutedContext context)
    {
        if (context.Exception is HttpResponseException exception)
        {
            context.Result = new ObjectResult(new {Mensagem = context.Exception.Message})
            {
                StatusCode = exception.Status,
            };
            context.ExceptionHandled = true;
        }
        else if (context.Exception is Exception)
        {
            var message = context.Exception.InnerException != null ? context.Exception.InnerException.Message : context.Exception.Message;

            context.Result = new ObjectResult(new RetornoExceptionApi(message))
            {
                StatusCode = StatusCodes.Status500InternalServerError
            };

            context.ExceptionHandled = true;
        }
    }
}

简单明了。我一直在使用它来捕获自定义HTTP异常，其中HttpResponseException是基类。这就是它看起来的样子：

public class HttpResponseException : Exception
{
    public int Status { get; set; } = StatusCodes.Status500InternalServerError;

    public HttpResponseException(int statusCode)
    {
        Status = statusCode;
    }
}

没什么。这是404状态代码的自定义例外：

public class NotFoundException404<TKey> : HttpResponseException
{
    private string _message;

    public NotFoundException404(TKey id) : base(StatusCodes.Status404NotFound)
    {
        _message = $"Nenhum objeto encontrado! ID solicitado: { id }";
    }
    public NotFoundException404(long id) : base(StatusCodes.Status404NotFound)
    {
        _message = $"Nenhum objeto encontrado! ID solicitado: { id }";
    }
    public NotFoundException404(string message) : base(StatusCodes.Status404NotFound)
    {
        _message = message;
    }

    public override string Message => _message;
}

此异常是从与HTTP其他异常相同的基本服务引发的，例如：

    protected async Task DeleteAsync(TKey id)
    {
        var entidade = await GetEntidadeExclusaoAsync(id);
        try
        {
            await _repository.DeleteAsync(entidade);
        }
        catch (SqlException e) when (e.Number == 547)
        {
            throw new ForeignKeyViolationException();
        }
        catch (Exception ex)
        {
            if (ex.InnerException != null
                && ex is SqlException
                && ((SqlException)ex).Number == 547)
                throw new ForeignKeyViolationException();
        }
    }

---

那个不起作用的异常在我的过滤器中为空，我不知道为什么。有什么建议吗？

这里的主要问题似乎是我很愚蠢。我停下来以更彻底的方式检查代码，问题不在于过滤器，而是我如何尝试提出ForeignKeyViolationException。这：

应该是这样的：

    catch (Exception ex)
    {
        if (ex.InnerException != null
            && ex.InnerException is SqlException
            && ((SqlException)ex.InnerException).Number == 547)
            throw new ForeignKeyViolationException();
        else
            throw ex;
    }

德普

更新

johnny 5的答案更简洁，效果也更完美，这无疑是首选的解决方法：

catch (Exception ex) when ((ex.InnerException as SqlException)?.Number == 547)
{
    throw new ForeignKeyViolationException();
}

---

看起来你已经找到问题的答案了。不过，我会努力建立在你的答案之上。可以使用when子句使函数更具可读性

catch (Exception ex) when ((ex.InnerException as SqlException)?.Number == 547) {
    throw new ForeignKeyViolationException();
}

---

我认为您犯了一个错误，SqlExceptionex.InnerExceptionex应该这样读：SqlExceptionex.InnerException。请参阅我的答案以了解优化和改进readability@johnny5是的，我在传递代码时搞砸了，只是更新了我的答案。我会尝试一下你的外观，测试后再更新一次。我不知道这样的时候你还能用。事实上，直到上周我才知道你什么时候起床。顺便说一句，您遗漏了几个括号，编译器仅在ex.InnerException作为SqlException？时才允许。Number==547

    catch (Exception ex)
    {
        if (ex.InnerException != null
            && ex.InnerException is SqlException
            && ((SqlException)ex.InnerException).Number == 547)
            throw new ForeignKeyViolationException();
        else
            throw ex;
    }

catch (Exception ex) when ((ex.InnerException as SqlException)?.Number == 547)
{
    throw new ForeignKeyViolationException();
}

catch (Exception ex) when ((ex.InnerException as SqlException)?.Number == 547) {
    throw new ForeignKeyViolationException();
}