If you are Qlik "scripter" or building advanced Qlik Dashboards ( Qlik Sense, QlikView), then you will come across the $(...) and $(=...) constructs within measure formulas or within the Qlik load script.
| Construct |
Scope |
Explained |
| $(...) |
Load Script |
example $(var1)
injects the content of the variable v1 betweem the $( and ).
|
| $(...) |
Measure Formula |
example $(var1)
executes the variable like code and inserts the result between the $( and ).
|
| $(=...) |
Measure Formula |
example $(=Year(Today()))
injects the result of the ad-hoc formula =Year(Today()) into the place between $( and )
|
$(...)
So far so good. Some believe, you always have to use the syntax $(...) together with variables, but that is not right. Assume you set the variable v1:
LET v1 = 'Qlik';
and you want to use the variable in a color formula:
If('$(v1)' = 'Qlik', 'green', 'gray') // is identical to
If(v1 = 'Qlik', 'green', 'gray')
but the 2nd syntax is simpler. Only in Load Script, when you use variables within a LOAD statement, all names you use there are considered field names, not variables; there you'd have to use the $(...) syntax to resolve the variable.
However it is a practice to use variables also to carry formulas, say
SET expr1 = Sum(Sales);
Now, if you create a measure in a chart and put =expr1 what you will get is the static text 'Sum(Sales)' which is the context of the variable, and not the calculation result. Here you must use =$(expr1) to get the content Sum(Sales) interpreted for the respective measure.
$(=...)
Shifting gears and make a bit more complex example for your load script:
SET smodifier = Segment={"mid-market"};
SET expr2 = Sum({< $(smodifier) >} Sales);
SET expr3 = Sum({< $(smodifier), SalesYear={$(=Year(Today()))} >} Sales);
Obviously, in expr3 you would like to dynamically filter SalesYear to the current year using a set-analysis syntax. But what will happen?
The expr2 will work. According to what I wrote earlier, the expr2 will inject the smodifier variable content within expr2 and it will contain Sum({< Segment={"mid-market"} >} Sales);
Note, that the text $(smodifier) is no more part of expr2, because the replacement of the $(...) happens already in script run time.
expr3, however, will not work, because the $(= ...) will be blank. Remember, $(=...) doesn't work within script. The variable expr3 will, unintendedly, contain an empty text within the SalesYear set-modifier:
Sum({< Segment={"mid-market"} , SalesYear={} >} Sales);
In order to set a variable in load script to carry the $(=...) construct you have to use an artificial syntax, that separates the $ from the (, such as $:(...) -- see the colon sign inbetween!
Same goes for $(...) construct, which you intend not to resolve at script execution, but in the frontend.
Finally, replace the $:( to $( by calling the following SUB routine (copy/paste it into the beginning of your script from here https://raw.githubusercontent.com/ChristofSchwarz/QlikScripts/master/FixVariables.txt )
SET var1 = 'US';
SET smodifier = Segment={"mid-market"};
SET expr3 = Sum({< $(smodifier), SalesYear={$:(=Year(Today()))} >} Sales);
SET expr4 = Sum({< $(smodifier), Cntry={"$:(var1)"} >} Sales);
CALL FixVariables('expr3, expr4');
After this what you will get in the variables is:
- expr3: Sum({< Segment={"mid-market"}, SalesYear={$(=Year(Today()))} >} Sales);
- expr4: Sum({< Segment={"mid-market"}, Cntry={"$(var1)"} >} Sales);
Now expr3 and expr 4 can be used in a measure in the Sheet objects like
=$(expr3)
Note, that Qlik can resolve nested constructs, for example there is a $(=...) within $(expr3) and a $(...) within $(expr4) which will be resolved.
Hope this helps understand the difference between $(...) and $(=...) and when used in script as opposed to measure formulas.
