Is there any WebDAV endpoint or property that can be used during a PROPFIND or similar request to obtain the actual binary data for a preview/thumbnail? I’ve seen discussions and posts about it elsewhere, but haven’t been able to figure out if this is available.
I know I can get a “hasPreview” indicator back, but what I’d like is to be able to fetch all entries for a given folder and their possible previews/thumbnails in one request.
I’m not an expert with webdav but I think these are separate endpoints.
That’s what I’m afraid of. It’d be nice if I could specify this in the request. One request with a little bit more information being returned (and possibly more work being carried out on the server side), is typically faster than two separate requests and post-processing on the client side. At least in my experience. Thanks for responding.
It really depends. If the thumbnails have to be generated the request will slow down and you get a O(n) complexity without any means of concurrency.
The single request approach isn’t always faster. Especially with HTTP2 and pipelining you get a lot more out of the multi request approach than you would with 1.1 a few years ago. Of course every request has an overhead but with large directories and the expensive preview generation it might be marginal.
I guess we’re both half-right and half-wrong then 
It’d be nice if this was application agnostic and had nothing to do with Photos/Gallery/Explorer but instead was handled as a core functionality where previews/thumbs are always generated and kept on the server, ready to be served. And also if there were core settings like:
[ ] Generate thumbnails for graphics file types/images
[ ] Generate previews for other supported documents
And then a size selector for both of these settings, but when you ask for a “preview” or “thumbnail”, you get it through one unified interface.
Which is expensive and the additional server load has to be well balanced. Preview Generator - Apps - App Store - Nextcloud tries to fix this a bit.
Indeed. But NC already has OCC already has file scanning functionality for other purposes. So one could leave it up to root/admin/sysop when these things are run. And it looks like this is more or less the approach “Preview Generator” has taken.
So, the question still stands about the endpoint(s)
Is the endpoint question (i.e. it being unknown) still open? I also would like to access the preview/thumbnail using Webdav (or alternative for that matter).
AFAIK, it’s still “open”, or possibly WAD (“working as designed”).
There is the possibility to request the existing preview.
GET: https://cloud.yourserver.org/core/preview?fileId=11750924&x=250&y=250
Send username and password in the header for authentication.
If there is no preview image, a status 404 is returned.