Declare Variables

Ignition
, ,
1

Hello everyone.

I would like to know if it is possible to record values in variables. I would like to declare at the beginning of the program and use it in the other parts of the script for example:

PrinterNameTest will come from the SQL database using runNamedQuery when the program is opened(this part is okay)

def Variables(self):
	vPrinterName = PrinterNameTest

def ShowsPrinterName(self):
	SystemTest.Variables(self)

	view = self.view
	vPath = 'root/FlexTitle/'

	view.getChild(vPath + "lbProgTitleName").custom.PrinterName= vPrinterName

The problem in the above code is that I can't use the variable throughout the other parts of the script other than calling it every time, instead use only vPrinterName

2

There are multiple ways to store data in ignition. Usually not through scripting, though possible.

In your case, it looks like you're looking for session custom properties.

1 Like
3

Just to expand on that because I think this is something that confuses a lot of people -

if a variable is shared among all users/the GW and it is calculated in some fashion (value from DB, or OPC tag, or expression on the current time) - use a Gateway Tag

If the variable is specific to the current client (vision or perspective client)and is calculated in some way - use a client tag or custom session property

If the variable is just specific to a project library and is a constant - declare it in a project script library at the top like PRINTER_NAME = 'someName' and reference it via myLibrary.PRINTER_NAME.

You can also set top level variables of scripts to do more a la @pturmel's suggestion elsewhere on this forum, but personally I find for most use cases the above as I described is sufficient.

1 Like
4

If just within a script, use a top level global as Brian suggests. You can write to such a global from within a function by the using python/jython's -- wait for it -- global statement. :grin:

3 Likes
5

Thanks all for the return.

The situation here is (Perspective Designer):
I have returned data from SQL and I stored it in custom property like:

I have a script in Project Liberty named ProjTest.

view.getChild(vPath + "lbProgTitleName").custom.PrinterName

In this script, I have a lot of scripts, and I would like to declare the variable to use in another def in the same script.

def Variables(self):
	global vPrinterName 

	view = self.view
	vPath = 'root/FlexTitle/'

	vPrinterName = view.getChild(vPath + "lbProgTitleName").custom.PrinterName
	x=2
	y=3

def ShowsPrinterName(self):
	view = self.view
	vPath = 'root/FlexBody/'

	view.getChild(vPath + "XPTO").props.text = vPrinterName

How I can get this variable vPrinterName declared before and use it in other parts of my code?

6

Assign something as a default at the top level (outside any def).

vPrinterName = 'Default'

def Variables(self):
	global vPrinterName 

	view = self.view
	vPath = 'root/FlexTitle/'

	vPrinterName = view.getChild(vPath + "lbProgTitleName").custom.PrinterName
	x=2
	y=3

If you need x and y to propagate to other functions, do the same with them.

1 Like
7

Awesome @pturmel, thank you so much.
I Add the "Default" to my script and works perfectly.