31 August 2022

How to reuse script in Qlik Sense

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Every Friday at Bitmetric we’re posting a new Qlik certification practice question to our LinkedIn¬†company page. Last Friday we asked the following Qlik Data Architect certification practice question about reusing script in Qlik Sense.

Qlik certifcation test question about reusing script in Qlik Sense and QlikView

The correct answer is C: On the server, store the script as a QVS file

Given the fact that in bigger environments you will probably have to work with multiple developers or in bigger teams it is wise to have certain parts of the script readily available for reuse. By doing this, certain scripting logic and definitions are defined in a fixed place and thus possible to be reused everywhere. This is done by adding these parts of the script to a .QVS file and including them in the script by using include or must_include.

Reusing script in Qlik Sense, an example

Lets take the script below as an example. In here we define the various stages of publishing of the app based on a prefix given to the filename. For example [DEV] Sales Dashboard. This tells us that the Sales Dashboard is currently in the development phase. The script below defines based on this prefix that the variable vDTPFolder should be dev. This is used to determine the load location of the QVD files. It is not uncommon for development and testing data to be different datasets then the final production dataset. So in this case ‘[DEV] Sales Dashboard’ will load from: [lib://$(vDTPFolder)/Facts.QVD].

IF MATCH(LOWER(TEXTBETWEEN(DocumentTitle(),'[', ']', 1)), 'tst') THEN
LET vDTPFolder = 'tst';
ELSEIF
MATCH(LOWER(TEXTBETWEEN(DocumentTitle(),'[', ']', 1)), 'dev') THEN
LET vDTPFolder = 'dev';
ELSE
LET vDTPFolder = 'prd';
ENDIF;

Since this DTP cycle will be used everywhere in the corporation’s environment, we want to use this script in every single application. Instead of answer A and mailing this script to all developers, it is a far better and more sustainable solution to store this on a server. This keeps maintainability to a minimum, since if changes occur, it is manageable from a single location. Also all newcomers can easily add this to their applications or understand what is happening.

Storing Qlik script externally

The script above needs to be stored before we can use it. This can be done by storing it as a .QVS file. QVS stands for QlikView Script and indeed comes from QlikView. In QlikView it was possible to export a whole script page at once to a QVS file. Under the file option you select ‘export to Export to Script file’ and this creates a QVS. While Qlik Sense is able to use QVS files, it is no longer possible to export them in the same manner. When using Qlik Sense you simply copy and paste the script you wish to reuse into a text file and store it. You can store this under .QVS or .TXT, since both will work.

Including the script

To include the script, we need to add it to the script in the data load editor. This is done by using include or must_include. The difference in both being, that must_include will give an error if the file cannot be found, while include fails silently. The syntax is as following:

$(Include=filename)

$(Must_Include=filename)

So if we store the example above as DTPInclude.QVS and wish to have a notification when the file cannot be found, we use the following line in the script:

$(Must_Include=lib://Scripts/DTPInclude.QVS);

Please be aware that there may be no spaces between the equal sign, otherwise it will not work. When reloading Qlik will now run the stored script as it was there.

That’s it for this week. See you next Friday?

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