topic AW:Dropping temporary variables after reload in QlikView

Dropping temporary variables after reload

Mon, 25 Oct 2010 10:29:09 GMT

Is there a way in QV to drop/hide temporarily used variables in a script ?

When reloading QV files, we are using quite some temporary variables (current date, number of years to reload, start year, QVD - folderpaths, ...) that are of no use for QV professionals and/or end users

Is there a way to drop (selected number of) variables at the end of your reload script or at least hide them one way or another for the professional / end users ? The professional user will often make use of variables himself (we encourage this instead of hard coded values), but the variable list tends to become quite long with variables that are only needed during the reload stage. Quite some variables are set at the beginning of the reload script using one or more includes (create once / use everywhere) so it would be nice if we could run an include at the end that removes the 'unnecessary' variables from the QV file.

AW:Dropping temporary variables after reload

skn — Mon, 25 Oct 2010 10:46:47 GMT

Hi,

a simple

set vVariable = ;

would do the job.

AW:Dropping temporary variables after reload

Mon, 25 Oct 2010 11:07:24 GMT

That is not exactly what I mean.

It's not that my professional / end users may not see the contents of the variable, I mean the variable itself.

The include's contain variables for database connections, network paths to store QVD files, ...

All these variables are now stored within the several QV applications, while they are only of use during the reload sessions itself.

I was thinking of a way drop (or hide) them at the end of the reload (compare it with going to the variable overview and deleting them manually).

AW:Dropping temporary variables after reload

Miguel_Angel_Baeyens — Mon, 25 Oct 2010 12:38:16 GMT

Hello,

Depending on how are you loading your document, I'd give a try to create a macro with the code

Sub CleanUp ActiveDocument.RemoveVariable "vVar"End Sub

And trigger it in the Settings menu, Document Properties, Triggers, OnPostReload.

Hope that helps.

AW:Dropping temporary variables after reload

danielrozental — Mon, 25 Oct 2010 13:34:21 GMT

If you do it in the "OnPostReload" event, it won't work with publisher.

AW:Dropping temporary variables after reload

Tue, 06 Dec 2011 08:38:08 GMT

In the meantime I am using the Publisher so guess the suggested solution will not work. Any other ideas ?

Re: Dropping temporary variables after reload

chrisbrain — Wed, 09 Oct 2013 12:52:28 GMT

Also interested in an answer to this. Sometimes we might end up storing credentials in QlikView variables during the load script cycle. Is there a way to ensure these are blanked after the reload has run (even if the reload fails for some reason?)

Re: Dropping temporary variables after reload

CELAMBARASAN — Wed, 09 Oct 2013 13:00:38 GMT

Hi,

At the end of the script you can drop the variables like

Set vVariable = ;

Set vVariable = Null();

It will remove the variables.

Re: Dropping temporary variables after reload

chrisbrain — Wed, 09 Oct 2013 13:27:29 GMT

Does this still work if there is an error during the reload and this part of the script is never reached?

Re: Dropping temporary variables after reload

flipside — Wed, 09 Oct 2013 13:38:17 GMT

You can also loop over a variable list and set them to Nothing at the end of the script ...

for each v in 'a','b','c','d','e','v'
LET '$(v)' = Nothing;
next v;

... but this won't run if there's been a failure. In that case you would need to wrap error handling around all or parts of the code and then test for failures to determine if variables need cleaning up.

flipside

Re: Dropping temporary variables after reload

ThornOfCrowns — Wed, 09 Oct 2013 14:01:13 GMT

If that part of the script isn't reached, then the code won't be triggered.

Re: Dropping temporary variables after reload

Wed, 09 Oct 2013 14:04:57 GMT

If I try to perform this, I end up with all the variables still in my QV file but with a value 'Nothing' or 'Null()'.

That is not exactly what I want. In the beginning of each QV file I add all the workpaths (QVD, QVW, ...) by means of variables. At the end of the script, I do not need these variables anymore and I would like to remove them. They are of no value for the end user.

Re: Dropping temporary variables after reload

ThornOfCrowns — Wed, 09 Oct 2013 14:10:15 GMT

The SET Variable =; syntax only works with variables crated within that load script, I understand.

Re: Dropping temporary variables after reload

swuehl — Wed, 09 Oct 2013 14:15:05 GMT

The proposed method should work, e.g. when using these statements in a just created document script:

Let x = 10;

Let y = 20;

Let z = x+y;

Let x= NULL();

Let y= NULL();

Only variable z should get to the UI, and should hold 30. x and y are deleted at the end of the script.

AFAIK, this deletion only works if the variable was newly created in the script, if it already passed to the UI once, a following script run won't completely delete the variable, you'll need to delete it in the variable overview once, then subsequent script runs should create / delete it.

Re: Dropping temporary variables after reload

Wed, 09 Oct 2013 14:34:51 GMT

I tried the following :

Through a general include that is inserted in the beginning of the script (of all QV files), a number of paths are assigned to a variable :

LET salesdir = 'S:\In Production\QVD\Sales\';

LET accountingdir = 'S:\.....';

At the end of the script, I now built an include containing the following code :

LET salesdir = Null();

LET accountingdir = Null();

Just before reloading the file, I removed these variables from the overview and saved the QV file.

After the reload, I checked the variable overview and all variables are still there showing Null() as a value.

In my case, the variables are not removed. Running QV 11 SR2

Re: Re: Dropping temporary variables after reload

swuehl — Wed, 09 Oct 2013 14:46:33 GMT

Can't reproduce this here on QV11.20 SR3

Attached my test files.

Re: Dropping temporary variables after reload

pgrenier — Wed, 09 Oct 2013 14:51:10 GMT

Hello Xavier,

Please be careful, the LET and the SET instructions do not react the same way when assigning values to a variable. The LET statement forces the immediate evaluation of the expression following the "=" sign, whereas the SET statement defers the evaluation to when the variable is actually used.

So, if you write

LET a = Null();

The variable will be immediately be assigned the a null value, and if it did not already exist before the execution of your script, it shall be removed from the memory.

If you write

SET a = Null();

The variable will be assigned the expression "Null()" and will be kept in memory for later use.

Hope this helps, regards,

Philippe