Newtonsoft.Json System.InvalidOperationException：不允许同步操作

Question

我收到以下异常，但不知道如何解决。我不想设置AllowSynchronousIO = true。 MS 从 3.0 开始决定不再默认允许同步，这是有充分理由的。那么我该如何解决这个问题呢？

System.InvalidOperationException: Synchronous operations are disallowed. Call ReadAsync or set AllowSynchronousIO to true instead.
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpRequestStream.Read(Byte[] buffer, Int32 offset, Int32 count)
   at System.IO.StreamReader.ReadBuffer(Span`1 userBuffer, Boolean& readToUserBuffer)
   at System.IO.StreamReader.ReadSpan(Span`1 buffer)
   at System.IO.StreamReader.Read(Char[] buffer, Int32 index, Int32 count)
   at Newtonsoft.Json.JsonTextReader.ReadData(Boolean append, Int32 charsRequired)
   at Newtonsoft.Json.JsonTextReader.ParseValue()
   at Newtonsoft.Json.JsonReader.ReadAndMoveToContent()
   at Newtonsoft.Json.JsonReader.ReadForType(JsonContract contract, Boolean hasConverter)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
   at Newtonsoft.Json.JsonSerializer.Deserialize(JsonReader reader, Type objectType)
   at Newtonsoft.Json.JsonSerializer.Deserialize[T](JsonReader reader)

Answer 1

使用Microsoft.AspNetCore.WebUtilities.FileBufferingReadStream 类作为流的包装器解决了这个问题。这允许您异步访问流，然后将流公开给像 Newtonsoft.Json 这样的同步工具，而无需为整个解决方案启用 SynchronousIO。 MVC 也通过使用 FileBufferingReadStream 类来解决此错误，因此它经过了很好的测试。

https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.webutilities.filebufferingreadstream?view=aspnetcore-3.1