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salvois / LargeXlsx

A .net library to write large Excel files in XLSX format with low memory consumption using streamed write.
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Broken Excel fail generated when writing to not seekable stream #9

Closed aboryczko closed 2 years ago

aboryczko commented 2 years ago

Hi,

I've tried to use this library to stream Excel files on the fly via ASP.NET Core. My use case prohibits me with caching it in memory and I end up using the raw HTTP response stream. The file generated seems ok at first, but when I load it with Excel it tries to repair it and without any data loss the file is opened. The only difference between a correct file and the broken one is that the underlying ZIP file has the general purpose bit flag set to (bit 3). I know that this is more of an Excel issue but did anyone have any luck working around that?

aboryczko commented 2 years ago

I guess it's not totaly Excel related because I've exchanged the SharpCompress library for the .NET internal compression implementation and my generated files work correctly.

aboryczko commented 2 years ago

so there is an error in the compression library that adds some strange bytes in the middle of the content every N bytes. I will go continue this thread there.

aboryczko commented 2 years ago

@salvois if it would be ok with you I could create a PR that would replace SharpCompress with the built-in .NET Core implementation and bumped it to v2.0. It worked fine for me.

salvois commented 2 years ago

Hi @aboryczko , last time I checked, the built-in compressor in .NET failed to produce a ZIP64 with content larger that 4 GiB considered valid by Excel. It refused to open it altogether. If this is still the case, unfortunately I cannot switch the underlying compression library. Have you tried this too? Thanks, Salvl

Erior commented 2 years ago

Would be nice if you can try out the 0.32.1 release of sharpcompress, that was linked to this issue

salvois commented 2 years ago

Hi @Erior , many thanks for pointing that out and for your help, I will try it next week! Salvo

salvois commented 2 years ago

Hi @aboryczko , @Erior , the issue seems to be solved using SharpCompress 0.32.1. I have just released LargeXlsx 1.5.1 with the updated dependency. Please have a try and let me know. Thanks for your contribution! Salvo

aboryczko commented 2 years ago

Thanks everyone, I can also confirm that the issue has been resolved :)