With out current intranet application we have drag and drop for files in firefox. Works nicely for one file, but if I drag 20 or more in, there are two main problems: ConflictError and POSKeyError. The former is quite understandable - 20 concurrent write requests on the same object could cause that. The POSKeyError however signals "POSKeyError("No blob file", oid, serial)" . But I have uploaded the blob. And no matter what I try, I can't force it to be written.
Or can I? I needed to pass a StringIO instance to the BlobField.set (so that I can pass on the filename), and it turns out that this StringIO is adapted to IBlobbable using plone.app.blob.adapters.stringio.BlobbableStringIO. And there, in feed, they write to blob.open('w'), but never close it.
Changing it to
def feed(self, blob):
""" see interface ... """
pos = self.context.tell()
bfile = blob.open('w')
seems to help a lot - at least now I can't reproduce the POSKeyError anymore.
Maybe I need to post a bug report?