topic Re: variables evalution confusion? in QlikView

variables evalution confusion?

Tue, 24 Nov 2015 09:21:52 GMT

for i=0 to noofrows('VariablesTable')-1

LET var_name= peek('VariableName',i,'VariablesTable');

LET $(var_name) = peek('VariableValue',i,'VariablesTable');

TRACE Load Variable: $(var_name) = $($(var_name));

how it can evaluated?

Re: variables evalution confusion?

tamilarasu — Tue, 24 Nov 2015 09:24:48 GMT

Hi Josna,

Use debug option to see the evaluation.

Re: variables evalution confusion?

Tue, 24 Nov 2015 09:27:12 GMT

Hi jasna,

you'll need to expand 'i' when used in the peek

$(i)

hope that helps

Joe

Re: variables evalution confusion?

Mark_Little — Tue, 24 Nov 2015 09:30:35 GMT

Hi,

I am not sure what you are trying to achieve?

I wouldn't approach like approach the above maybe something like

SET var_name= peek('VariableName',i,'VariablesTable');

LET var_Value = peek('VariableValue',i,'VariablesTable');

TRACE Load Variable: var_name = $(var_name);

Some more information would be useful.

Mark

Re: variables evalution confusion?

Tue, 24 Nov 2015 09:40:44 GMT

Dear Mark i am not trying to achieve in my application just i saw this function in demo app i cannot underdand this one so for more information purpose i post that

Thanks and Regards

Josh

Re: variables evalution confusion?

avinashelite — Tue, 24 Nov 2015 09:46:17 GMT

Hi josna,

As Nagaraj mentioned you can make use of the debug window to see the what values getting set in the backend.

or you can use the TRACE function to popup the values during the reload

I feel your getting confused in the $ sign expansion ? $ represent the current value of the variable

Re: variables evalution confusion?

Mark_Little — Tue, 24 Nov 2015 09:47:03 GMT

HI Josh,

Not sure where you have seen it,

But basically it looks like the are loading a a number of formulas and then the results and the bringing up a trace to see if they match

for example

Row	Variable Name	Variable value
1	2+2	4
2	3+3	6

So the we would have

LET var_name= 2+2;

LET $(var_name) = 4;

Trace would return 4 = 4

Mark

Re: variables evalution confusion?

Peter_Cammaert — Tue, 24 Nov 2015 09:59:10 GMT

This is a very simple double-dollar expansion.

The idea is to have a list of variables in an external data file, and their values. You can store this in an Excel file or a QVD. It works as an external configuration file.

What happens is that the FOR loop first reads a variable name, and then assigns a value to that variable name. all without knowing the name of the variable beforehand. For example, my Excel may contain the following:

VariableName VariableValue

vMySetting1 5

The first Let stores 'vMySetting' in variable var_name.

The second LET expands to:

LET vMySetting1 = peek(...

and assigns a value to the variable I just came to know.

Very powerful technique. Gives you the freedom to configure your document in the wildest manner, all without visiting the load script. Ever.

Peter

Re: variables evalution confusion?

engishfaque — Tue, 24 Nov 2015 10:15:58 GMT

Dear Josna,

We use this technique mostly making dynamic variables,

Step 1: for i=0 to noofrows('VariablesTable')-1

Here you're using loop from value 0 to Last number of rows - 1

Step 2: LET var_name= peek('VariableName',i,'VariablesTable');

Here you're evaluating and assigning variable name to "var_name"

Step 3: LET var_Value = peek('VariableValue',i,'VariablesTable');

Here you're evaluating and assigning variable value to "var_Value"

Step 4: TRACE Load Variable: var_name = $(var_name);

Here you're only printing variable using Trace keyword.

For more clarification, kindly find attached document and screenshot.

Kind regards,

Ishfaque Ahmed