try to download a file from deta drive through a endpoint

[ooralas]

I have a nodejs-micro. i have already uploaded a couple of PDF files
, which worked without any problems. When I try to
make the files available for download through an endpoint,
it did not work.
I get a BLOB object from the drive. If I do this locally (see the code), I can use this code

const reports = deta.Drive('reports')
const file = await reports.get(fileName).then(a => a.arrayBuffer())
  fs.writeFileSync('./' + fileName, Buffer.from(file))
  res.download(fileName)

where i convert the BLOB object to a PDF file, and then make it available for Download. But when i deployed my micro, this didn't work because I'm probably not allowed to access the filesystem on deta.
So my question is, as described above, can I make a file, that is in Drive, available for download through an endpoint ?

[jnsougata]

Deta drive doesn't support that. But yes you can store the file in micro at /tmp dir as that's only runtime writable

[ooralas]

@jnsougata thanks.
which fs Methods can i use in /tmp? i am getting "Bad Gateway" when i try to fs.unlinkSync(), in addition when i tried to res.download() a pdf file, which i stored on /tmp locally and deployed on my micro, i got an empty pdf file with same page numbers like the original file.
what should be the problem ?

[abdelhai]

@ooralas micros do not persist data. you can't download things there and expect them to exist the next time.
/tmp are meant to be temporary place to hold files while you process them during a specific request.

to make it a bit more clear, if you download a file during with one request and tried to read it in the other, it's almost always not there.

to be able to help you, please provide more details on what you're trying to achieve on a high level.

[ooralas]

thanks for you answer.

I have 23 pdf files that I want to make available for download through a specific URL. I have saved the files on Drive.
By the parameter, I know which file to download, which I then retrieve from Drive.
From Drive I get a buffer, which I handle as follows, and then send the file for download. Locally it works, I get the file and I can open it. But when I deploy my micro, I get the file with the correct file size and the correct page count, but the pages are blank.

route.get('/p/:name', async (req, res) => {
  const blob = await berichte.get('wb1.pdf')
  const buffer = await blob.arrayBuffer()
  console.log(buffer)
  res.setHeader('Content-Type', 'application/pdf')
  res.setHeader('Content-Disposition', 'attachment; filename=wb1.pdf')
  res.send(Buffer.from(buffer))
}

p.s.: the files remain in /tmp.
i saved 3 files there yesterday and they are there since then.

[ooralas]

@abdelhai

[aavshr]

hi @ooralas the code looks good to me, can you please try to put the env var BINARY_CONTENT_TYPES=application/pdf for the Micro and try again? The issue might be because of this, more here: https://docs.deta.sh/docs/common_issues#nodejs-micros-cannot-serve-binary-files

Also, please bear in mind that Micros have a payload size limit of 5.5 Mb so larger files can't be served from the Micro.

[ooralas]

it worked thank you.

Can you please tell me how can i clean /tmp directory on my micro ? i tried fs.unlinkSync('./tmp/wb2.pdf') i didn't work. i got a bad gateway error, which fs functions can i use on micro ?

[aavshr]

/tmp is automatically cleaned @ooralas .

I'm sorry I'm not fully aware what kind of APIs fs has but all functions that allow you to read from a file should work, and functions that need to write to a file only work for files in /tmp. Also you can try to look at the logs when there is a Bad Gateway error to try to see what exactly is the issue.

[ooralas]

@aavshr thanks for your answer, after i update the .env file it worked.

hi @ooralas the code looks good to me, can you please try to put the env var BINARY_CONTENT_TYPES=application/pdf for the Micro and try again? The issue might be because of this, more here: https://docs.deta.sh/docs/common_issues#nodejs-micros-cannot-serve-binary-files

Also, please bear in mind that Micros have a payload size limit of 5.5 Mb so larger files can't be served from the Micro.

@aavshr i couldn't mark you answer in the thread as an answer, so i will do it hier :).