node deletes data

[boenki]

It seems node-red-contrib-aggregator deletes data from the flow:

When I set a timestamp / part / whatever before this node, it's all gone except a payload.
Tested in mean value mode.

This is the complete msg object before this node:

5/9/2020, 11:44:25 PMnode: 78486d5.0eff714 bezug : msg : Object object payload: 55.1 _session: object type: "websocket" id: "f1410959.7c78e8" _msgid: "fafe8c20.c6ed5" uuid: "197a43a0-8af5-11ea-85cf-59284eee40d1" topic: "bezug" status: "bezug" timestamp: 1589060664898 parts: object id: "straße" index: 1 count: 2

and this is the output after the aggregator node
5/9/2020, 11:44:30 PMnode: eece9b3a.a2261msg : Object object topic: "" payload: 54.339999999999996 _msgid: "c31e3f0c.c923c"

Thank you

[jaggr2]

Hi boenki

That's correct, the node creates a new message by intent because there is no definition of how the node must combine properties of multiple input messages into one single output message, like take the properties from the first message, or the last, or all by overwriting or skipping existing properties.

I recommend creating a custom node before the aggregator which extracts wanted properties and readds them after the aggregator node in the desired way. Alternatively, I'm open to extending this node with corresponding settings. Sadly I don't have any spare time for developing this feature but I will accept and merge any pull requests.

[thomasvnl]

Hi boenki

That's correct, the node creates a new message by intent because there is no definition of how the node must combine properties of multiple input messages into one single output message, like take the properties from the first message, or the last, or all by overwriting or skipping existing properties.

I recommend creating a custom node before the aggregator which extracts wanted properties and readds them after the aggregator node in the desired way. Alternatively, I'm open to extending this node with corresponding settings. Sadly I don't have any spare time for developing this feature but I will accept and merge any pull requests.

Might want to at least mention that in your help/readme file. This had me by surprise and I was looking for the cause.

Also, regarding your question about how to handle/combine properties, I would probably do what the "join" node does (I think) which is use the properties from the last message it encounters (unless I am wrong and it actually merges all properties). If someone were to have issues with this, they can just aggregate on a per topic basis I suppose which keeps the properties segregated. Although not perfect (but then again what is), that would cover a lot of ground already and would keep it more in the likes of other nodes that do not modify/delete data they don't need to edit for their functionality to work.

And last but not least. At the moment, it even deletes the value of msg.topic if it was set on a message going in but not set on the aggregator node itself. This is pretty bad to be honest, as this is a way of tracking where a message comes from (just like what you use to aggregate on a per topic basis).

[pagaille]

+1 : the split and join nodes looks likely to be used in conjunction with your node. At least I was trying to do the same things and had the same issue as reported by @thomasvnl