topic Re: User-defined functions equivalent in Qlik Sense in App Development

User-defined functions equivalent in Qlik Sense

wdchristensen — Tue, 23 May 2017 17:03:21 GMT

From time to time I find myself rewriting the same code over and over again. A simple example might be something like removing special characters that are not stripped by the default trim function.

Replace(Replace(myFieldName, char(194), ''), char(160), '')

Now suppose I want to make a custom trim that will accept a field name and perform a replace action. Ideally, I would like this new function to be usable in the load script and as well as in the application. How can this functionality be accomplished to prevent unnecessary code duplication.

Re: User-defined functions equivalent in Qlik Sense

marcus_sommer — Wed, 24 May 2017 07:08:07 GMT

You could use a variable with parameters for it:

set eReplace = Replace(Replace($1, char(194), ''), char(160), '');

and then you call it:

...

$(eReplace(myFieldName)) as myFieldName

...

- Marcus

Re: User-defined functions equivalent in Qlik Sense

wdchristensen — Wed, 24 May 2017 14:20:44 GMT

Thanks for your reply. From what I can gather, this solution is for use in the load script. In my example this would probably work fine but in reality I am trying to show the truth evaluation for my set analysis conditions that I have put in variables as explained in another post (https://community.qlik.com/thread/261534?sr=stream).

So essentially I am repeating this measure formula 50 times:

=if((SUM({<$(vMarket)>} 2)) - (SUM({<1=1>} 1))=1,'True','False')

and I just keep changing vMarket to the next set analysis T/F condition. I am not sure I like this implementation so I really want to put it in a function so when I learn a better way I can make the change in one location and cascade the changes with as little rework as possible. Any suggestions?

Re: User-defined functions equivalent in Qlik Sense

rwunderlich — Wed, 24 May 2017 14:32:53 GMT

The solution Marcus proposed - variables with parameters - works in both load script and chart expressions.

-Rob

Re: User-defined functions equivalent in Qlik Sense

wdchristensen — Thu, 25 May 2017 13:54:38 GMT

The first attempt I tried to put the definition in an application variable and noticed that the keyword "Set" was not recognized. Once I put the variable definition in the load script and then I was able to call the "function" in the application just as stated. As always, I appreciate the help!

Are there any examples that show this technique for more complex "functions"? For example, a for loop or do while loop...

Re: User-defined functions equivalent in Qlik Sense

rwunderlich — Thu, 25 May 2017 17:12:02 GMT

Unfortunately, you can't use the technique with loops (easily). It needs to be a single expression, not a series of statements.

-Rob