Mongodb file download fix

[chf73]

We used the mongodb persistence in our try-out of the bays components and found the following issues when downloading files:

• file names are constructed containing the AAS ID (e.g. "http://smart.festo.com/id/instance/99920200616214522000030025") - this may not result in a valid filename
• when fetching files from mongodb collection they are not stored in a dedicated folder

Fixes:

• replace characters in filenames that may cause troubles by "_"
• use a temporary directory (previously generated) to save files fetched from mongodb

[FrankSchnicke]

Thank you very much for providing this PR! Would it be possible to sign the ECA?

[chf73]

Thank you very much for providing this PR! Would it be possible to sign the ECA?

Done!

[FrankSchnicke]

After some internal discussions, we realized that the issue is more complex than it seems. There are the following points that need to be considered:

• Backwards compatibility: If we change the way how filenames are generated, a file stored in the old way is not findable anymore. Thus, the logic needs to be adapted in a way that it still works with the old names, e.g., checking for the new filename on retrieval and if it does not exist, checking for the old filename. Storing a file always should utilize the new filename.
• Filename collision: By applying the regex, ids "id:" and "id/" would both be changed to "id_". Thus, if same idShorts are used, files may get overwritten. A possible solution for this would be to apply the regex as proposed by you and attaching the identifier-Hash to the resulting filename.

Would it be possible to update the PR the consider both issues?

[FrankSchnicke]

Is this PR still active? If no, I will close it in a few days

[chf73]

Is this PR still active? If no, I will close it in a few days

I am currently working on a solution that takes the named issues from your earlier comment into account, maybe I can provide a proposal this week.

[FrankSchnicke]

Thank you very much for updating the PR! Feel free to ping me when you're done with your implementations, I will then gladly review it again

[chf73]

Thank you very much for updating the PR! Feel free to ping me when you're done with your implementations, I will then gladly review it again

Ping ;-) ... the last commit fixed the failing test, so I am finished now - thnx for reviewing again 👍

[FrankSchnicke]

Looks good to me. Thank you very much for your contribution!