Send an array value to url

General
1

Hi!
When I get a value from a calculator node, I want to get the value thru a function node and supply the value to a url. If the value is negative, I want to insert the value zero.
I've tried using param but something is wrong. Maybe I need to change the array to a message first?

2

You haven’t provided enough information. What calculator node? What are you doing in the function node? What should the url look like?

3

image
Joining two values
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Comparing them
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Sending it through the funciton node

image
image604×507 8.95 KB

Adding the value in the url
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Getting this in return after a while

4

Cany you create a small flow demovstrating the issue. Use an inject node to start off. Then export your low and attach it to a reply.

It would be useful to give the ful name of the calculation node -i.e. node-red-contrib-?????

5

I am nearly there now, but the calculator can't send out a negative value.
So I want to do math in a function node instead. But I dont know how to do this.
Here is a picture. Row 3 is just for demonstration.
image

6

He when posting code, it is far better to copy + paste the code into a code block (click the </> button in the reply toolbar)

that way, someone assisting you doesnt have to read & re-type out the code from your screenshot.

As for using a function to deduct a from b...

msg.payload = b - a;

if you want that to be a value inside an array then...

msg.payload = [b - a];
7

Thanks!

msg['param'] = 
parseInt(msg['payload']) <= 0 ? 0:
msg['param'];
return msg;

When I get a negative value in the payload, I want the output to be zero.
What have I done wrong here

8

Did you realise the result will be in msg.param not msg.payload?

Also note that msg['param'] is the same as msg.param. You only need to use the square bracket notation if the property name includes special characters.

9

msg.param will be empty so should not be the 3rd part of parseInt(msg['payload']) <= 0 ? 0 : msg['param'];

This might be a bit better...

var pl = parseInt(msg.payload);
msg.origPayload = pl; //for checking in debug panel
msg.param = pl < 0 ? 0 : pl;
return msg;
10

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