Transformers don't seem to be able to drop messages

[codepope]

In 0.0.4, passing the better Msg object - and having to return it - means you can't return false - it generates an error message.

In previous versions, returning false (or some other non map/interface type) would mean the message was dropped from the pipeline.

[jipperinbham]

Good call, I think the best way to handle this is to create a new OpType of Noop that we can then check before sending the message downstream. Thoughts?

[codepope]

Sounds good - it has to be n Noop (as d for Drop is taken by Delete :) )...

[jipperinbham]

ha, good call, also, I'm not seeing where the codebase supported the ability to drop messages in transformer functions, can you show me an example where you had this working?

[codepope]

https://www.compose.io/articles/transporter-transformers-powering-up-your-data-transfer/

Creating and Skipping and Counting... These worked with hosted transporter, but I think I need to consult with Nick on the history.

[codepope]

I think we're talking effective side effect which has just iterated out, so bringing it back officially as Noop would be most excellent.

[jipperinbham]

Looking back through the changes to transformer, the ability to skip documents was removed here, 2682b08, when we changed from msg.Document to msg.Data and the type went from map[string]interface{} to interface{}. I've added this to the next milestone release since it's more of an enhancement we want to bring back and less of a bugfix.

[nstott]

👍 good plan