Join two strings in a SPECIFIC order after pressing ui_button?

Hello, there! I'm new here and a bit lost, to be honest.

In my Dashboard, I want the user to type in numbers in two separate fields, then press a button. After this button is pressed, I need to join the two strings originated from the data input but they have to be in a specific order so I can send it to a serial afterwards.

I tried using ui_button but it keeps sending the data separately into Debug; I also tried Join, but if I type in the second field and only then the first one, the message doesn't get the way I need it to be (not to mention the absence of buttons on Dashboard in this case!).

I'm using Node-RED v2.2.0 and not quite familiar yet with JSON and the like.

Hi and welcome to the forum.

This is a bit tricky, depending on your knowledge of all the stuff you can do with the nodes.

You are kind of right with the join node, but it won't guarantee the order of the two messages.

This needs a bit more magic that you know just now.

But for the sake of helping you get on your way, here is the basic idea of what you need to do:

The trick is with a function node because it has a bit more of the magic under its hood than the other nodes and can store messages for later use.

The problem you are having is that in node-red, everything is real time and no messages are stored. Unless you use something like the join node.
Good on you for trying/thinking of it.

So, first off each message will need to have a unique attribute so they can be identified.
This is only needed as far as the function node.

For this example, I'll make Message 1 and Message 2 easy to identify.

//  store the incoming message value.
if (msg.topic == "MESSAGE1")
if (msg.topic =="MESSAGE2")
msg = {};  //  wipe the message.

var a = context.get("message1");
var b = context.get("message2");

if (a.length > 0)
     if (b.length > 0)
               msg.payload = context.get("message1") + context.get("message2")
               return msg;

This was typed here, now and I haven't tested it.

But I hope that helps you understand what is needing to be done.

Good luck.

Ok, that code doesn't work. (I'm not that good)

But this does and it is an example as well.

[{"id":"319a422441bd214c","type":"function","z":"0918ee609bf69fc7","name":"","func":"//  store the incoming message value.\nif (msg.topic == \"MESSAGE1\")\n{\n     context.set(\"message1\",msg.payload);\n}\nif (msg.topic ==\"MESSAGE2\")\n{\n    context.set(\"message2\",msg.payload);\n}\nmsg = {};  //  wipe the message.\n\nvar a = context.get(\"message1\") || \"\";\nvar b = context.get(\"message2\") || \"\";\n\n\n\nif ((a.length) > 0)\n{\n     if ((b.length) > 0)\n         {\n               msg.payload = context.get(\"message1\") + context.get(\"message2\")\n               context.set(\"message1\",\"\");\n               context.set(\"message2\",\"\");\n               return msg;\n        }\n}","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":670,"y":1610,"wires":[["e18a85119048611f"]]},{"id":"b27b8df82741fb13","type":"inject","z":"0918ee609bf69fc7","name":"first","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"MESSAGE1","payload":"first","payloadType":"str","x":470,"y":1570,"wires":[["319a422441bd214c"]]},{"id":"c8c591968a100e7d","type":"inject","z":"0918ee609bf69fc7","name":"second","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"MESSAGE2","payload":"second","payloadType":"str","x":470,"y":1630,"wires":[["319a422441bd214c"]]},{"id":"e18a85119048611f","type":"debug","z":"0918ee609bf69fc7","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":850,"y":1610,"wires":[]}]
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Now that you sent me the example it seems a bit clearer. Thank you so much!
(btw, I've been copying and pasting so many flows from the forurm that my Node-RED looks like a Smörgåsbord :sweat_smile:)

But the thing for me is that. freakin'. UI. button!
I want the user to click on a "send" button in the Dashboard, in order for the "magic" of joining the stuff begin. As I've seen so far, the button does not have a "passthrough" action. Am I right?

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That's ok. Mine is like that too.

The button does have a pass through, but I don't think it does what you thing it does.

You can replace my inject nodes with button nodes and things should work.

the pass through is towards the bottom of the node.

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I did try to replace inject nodes with the ui_button ones in your example, but it didn't work out.
Captura de tela 2022-02-26 035059
Captura de tela 2022-02-26 035039
Am I missing any detail?

That's because (as I found out the hard way) the terms used are confusing.

It doesn't mean make it look like the button was pressed and send it's message.

It means, send the message you sent into the button node to the output.

So you will have to change the inject node to be the same as the button node.

And looking at the button node, you need to actually enter something in the payload section.

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You edited your comment in the EXACT moment I deployed and tested this solution. Talk about being in the very same page!
It worked. I will try to see if something similar happens with my original flow and let you know. Thanks!

Good I am useful to someone. :wink:

You could also try the ui_form node which assigns a property to each and sends both in one message which makes it easy to rejoin them however you wish.

I will take a look at it as well. Thanks!

It worked like a charm, @Trying_to_learn ! I had to add a pop-up notification, though. It is not what we desire, but it sends the info the way I need it to be sent and the serial takes it perfectly.

I will try the @dceejay suggestion as well to see if using the form can help shape up my UI better. But for that I'll need to study a little more on how to use the Form node.

I am so happy to be a part of this community :heart:

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