Wow, thanks for this information! Just last week I saw code that modified
attributes in a stream:
flowFile.getAttributes().entrySet().stream().filter(e ->
e.getKey().startsWith("foo"))
.forEach(e -> session.putAttribute(flowFile, "original-" + e.getKey,
e.getValue()));
and I wondered how that could possibly work since the return value of
session.putAttribute is ignored! Now I know.
-- Mike
On Tue, May 7, 2024 at 3:02 PM Russell Bateman <r...@windofkeltia.com>
wrote:
> Yes, what you described is what was happening, Mark. I didn't display
> all of the code to the session methods, and I did re-read the in-coming
> flowfile for different purposes than I had already read and written it.
> So, I wasn't helpful enough. In the end, however, I had forgotten,
> immediately after the call to session.putAllAttributes(), to update the
> resulting flowfile for passing to session.transfer(). That solved it for
> 1.1.2 which wasn't necessary for 1.13.2 or later versions. Being
> helpful, the newer versions made me a spoiled, entitled child and I will
> repent immediately.
>
> Thanks, guys! DevOps are happy they don't have to upgrade the customers
> to NiFi 1.13.2. (In a way, I'm unhappy about that, but...).
>
> Best regards,
>
> Russ
>
> On 5/7/24 11:53, Mark Payne wrote:
> > The call to session.putAttribute would throw an Exception because you
> > provided an outdated version of the flowFile (did not capturing the
> > result of calling session.write)
> >
> > Now, as NiFi matured, we found that:
> > (a) for more complex processors that aren’t just a series of sequential
> > steps it becomes difficult to manage all of that bookkeeping.
> > (b) it was not intuitive to require this
> > (c) the ProcessSession already had more or less what it needed in order
> > to determine what the most up-to-date version of the FlowFile was.
> >
> > So we updated the ProcessSession to automatically grab the latest
> > version of the FlowFile for these methods. But since you’re trying to
> > run an old version, you’ll need to make sure that you capture all of
> > those outputs and always keep track of the most recent version of a
> > FlowFile.
>
