Use "flow." payload in Button node

I want to set a flow variable via a button when its pressed. Can't find any docs on the format for this button payload option and the usual format I'd use in a function node as below (and several variants I have tried) flags syntax error:
Also tried without "flow." prefix in case that was automatically added by the node when using this option.

Hi @notnice

I assume you are talking about the ui_button node from node-red-dashboard?

Assuming it is, the payload is the value you want the node to send via a message. That's all. It doesn't provide a way to set a context value directly.

If you want that payload value to be set into context, wire the button node to a Change node configured to set the flow context value.

Yes, in the UI Button using this option. To me it it looks like it should be able to set a variable directly.


You are selecting the value it should send in the message. By selecting the flow. option you are telling the node to send a flow context value.

If you want to set a value in context, then as I said, you'd have to wire this node to a Change node.

Ah, got it - it only sends an existing named variable, not anew one. Thats a shame.
Thx for your quick response. :+1:
Could do with having such info documented :wink:

Well the info does already say
" Clicking the button generates a message with msg.payload set to the Payload field. If no payload is specified, the node id is used.
it doesn't say anything about setting other fields - but nor does it mention that it doesn't make a cup of tea. :wink:

Semantics :wink:
If you know what it means then its understandable. To me it read that the message payload would be created with whatever parameters I entered.
I am now the wiser :+1:

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