Currently, we have a feature in one of our products that allows you to upload an attachment to one of our objects to use as a thumbnail on the page it's displayed on. With attachments, I am able to build a URL that allows the site to grab that image for use, and everything works fine.
Because lightning will be doing away with attachments, switching instead to ContentDocuments, I thought I'd look into how to get them to work in a similar way. Unfortunately, I haven't been able to find a way to actually get a ContentDocument after getting it's Id. With Attachments, I could just use this url:
sitePrefix + '/servlet/servlet.FileDownload?file=' + attachment.Id
Is there a way to do something similar with ContentDocuments? It would suck pretty bad to tell our clients this just won't work anymore once SF decides to finally close access to attachments.