Try the new System.Text.Json APIs!

The Discussion

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  Blog link does not appear to work.

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  Broken blog link for anyone unable to find it:
  
  https://devblogs.microsoft.com/dotnet/try-the-new-system-text-json-apis/

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  Sorry, fixed now :)

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  Hi,
  
  I might not be understanding correctly but looking around I can't see how to read large files with Utf8JsonReader without the JSON fitting in memory. If I'm reading from a FileStream, it seems that Utf8JsonReader reads all bytes from the file into a Span structure. Is there a way of true streaming like JsonTextReader.
  
  Thanks
  
  Marshall

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  @tartufella:
  
  You read the data in chunks. Each chunk must be a single span. Sensible chunks are basically page sized (e.g. 4k). To read the next chunk, you construct a new reader, passing in the next block and the current reader state.
  
  https://docs.microsoft.com/en-us/dotnet/api/system.text.json.utf8jsonreader.-ctor?view=netcore-3.0#System_Text_Json_Utf8JsonReader__ctor_System_Buffers_ReadOnlySequence_System_Byte__System_Boolean_System_Text_Json_JsonReaderState_
  
  This allows you to fetch the next chunk in an async manner. Here is an example: https://docs.microsoft.com/en-us/dotnet/api/system.text.json.utf8jsonreader.-ctor?view=netcore-3.0#System_Text_Json_Utf8JsonReader__ctor_System_Buffers_ReadOnlySequence_System_Byte__System_Boolean_System_Text_Json_JsonReaderState_

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  Ahhh gotcha, I understand how it works now, thanks for the quick reply.
  
  /Marsh