WebClient.DownloadData在Bot Framework中引发异常

Question

我正在上传图片并使用带有DownloadData的WebClient来获取字节数组，但是现在它引发了一个例外：

Exception: State size exceeded configured limit.
[File of type 'text/plain']

在使用完全相同的图像之前，我还没有注意到这种行为。可能出了什么问题？

private async Task SendPhoto_ActivityReceivedAsync(IDialogContext context, IAwaitable<object> result)
    {
        Activity activity = await result as Activity;
        Activity activityReply = activity.CreateReply();

        if (0 < activity.Attachments?.Count)
        {
            if (activity.Attachments.FirstOrDefault().ContentType.Equals("image/jpg") ||
                activity.Attachments.FirstOrDefault().ContentType.Equals("image/jpeg") ||
                activity.Attachments.FirstOrDefault().ContentType.Equals("image/png") ||
                activity.Attachments.FirstOrDefault().ContentType.Equals("image/tiff"))
            {
                picImage = activity.Attachments.FirstOrDefault().Name;

                HttpClient httpClient= new HttpClient();
                picImageFile = await httpClient.GetByteArrayAsync(activity.Attachments.FirstOrDefault().ContentUrl);

                await context.PostAsync("Want to send another?");

                context.Wait(SendAnotherImage_ActivityReceivedAsync);
            }
        }
    }

更新：将WebClient更改为HttpClient.GetByteArrayAsync，问题仍然存在。 在PostAsync执行后立即在Bot仿真器中显示异常

Answer 1

问题是picImageFile是对话框内部的一个变量，因此对话框被序列化后会保存在状态中。两个选项

1. 下载图片并以该方法处理，而不将其保存在内存中
2. 将字节数组保存在外部存储器中。