Variable Expression: How to use declared variables in expression of the same node

[izaychik63]

I have 2 dates declared in Variable Expression as string constants.
I want to add new variable as a combination of previous ones. Recently someone answered the question but I cannot find it.
So, D1 is “7/1/21” and D2 is “7/31/21”
I need to add join(D1,"-“D2”)

Thank you

[ipazin]

Hello @izaychik63,

you wrote expression yourself.
join( variable("D1"), "-", variable("D2"))

Are you getting unwanted result with above or error?

Br,
Ivan

[izaychik63]

Ivan, Variable expression does not see variables D1 and D2

[elsamuel]

I think you’d need to use a single expression:

The node description says as much:

Additionally, intermediate results of functions or calculations can be stored within an expression by assigning them to variables (using ‘=’). This allows that these results can be reused in different parts of the expression after they have been assigned (see Examples).

[izaychik63]

Thank you, @elsamuel . This is looks as local variables for the section. My hope they could be global for the Variable Expression node.

[elsamuel]

If you want to set global workflow variables, you can right click on the workflow in the KNIME Explorer panel and select “Workflow Variables”:

You’ll then be able to define variables that will be available to every node in the workflow:

[ipazin]

Hello @izaychik63,

I see now what you mean. Using results from one expression in subsequent expressions (and/or defining global variables) is not possible within Column/Variable Expressions nodes. However there are tickets to enhance above mentioned nodes and I have noted your interest there.

For transparency reason you can also use Variable Creator node instead of workflow variables.

Br,
Ivan