Calling Macro function in Velocity template

Question

I am trying to figure out how to return a value from a velocity macro call and assign it to a varaible

my macro function looks something like this. its once in common shared macros files

#macro(getBookListLink, $readingTrackerResult)
   $readingTrackerResult.getBookListLink()
#end

I am need to assign the result of this macro to a variable in another velocity template file

I tried something like this

#set($book_list_link = #getBookListLink( $readingTrackerResult ))

but did not work. I tried with #,$ and with nothing in front of function getBookListLink. but nothing worked. Can not i return from a macro? something wrong with my macro?

But, As such if i call #getBookListLink( $readingTrackerResult ) separately in html file. it works and i can print the result to UI. But not able to assign to a variable.

I have a problem with extra spaces when I do this call. Sadly, even using the trick with comments (`##`), in the end of line, not worked. — Dherik, Aug 03 '15 at 16:47

score 32 · Accepted Answer · edited Aug 02 '11 at 20:15

32

Macros are not functions; they are for rendering output. However, if you don't mind losing the type and getting the result as text...

#set( $book_list_link = "#getBookListLink( $readingTrackerResult )" )

edited Aug 02 '11 at 20:15

fireshadow52

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answered Aug 02 '11 at 17:01

Nathan Bubna

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3

In case, if the function expects a string argument, then we need to use as follows: `#set( $book_list_link = "#getBookListLink('string_argument')" )` – Paramesh Korrakuti Sep 21 '16 at 13:07

score 7 · Answer 2 · answered Oct 10 '15 at 12:26

7

To get rid of spaces and blank lines use multi-line comments (#* comment *#):

#macro( myMacro $param )#*
  *#the_return_value#*
*##end

answered Oct 10 '15 at 12:26

Stefan Kleineikenscheidt

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score 3 · Answer 3 · answered Jan 31 '17 at 15:55

3

Instead of living with the string limitations for 'return values', preferably an externally defined result variable can be passed 'by reference', e.g.:

#macro(getBookListLink $inTrackerResult $outBookListLink)
    #if ($outBookListLink)
        #set ($outBookListLink = $inTrackerResult.getBookListLink())
    #end
#end

#set ($myLink = "")
#getBookListLink($myTrackerResult $myLink)
myBookListLink = "$myLink"<br/>

answered Jan 31 '17 at 15:55

Steffen

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Weird. This doesn't work for me. On the other hand if I do `#set($discard = $outBookListLink.put("returnKey", myReturnObject))` and then access it from outside, it works. – KulaGGin Dec 08 '22 at 17:39

score 1 · Answer 4 · answered Feb 04 '21 at 15:28

Just another example to illustrate the principle :

Macro definition :

#macro ( getValue $flag )
#if ( $flag )
#set($value = "TRUE" )
#else
#set($value = "FALSE" )
#end
${value}## (ends with a comment to avoid "END-OF-LINE" in the resulting string)
#end

Call :

#set($myval = "#getValue( true )" )

score 0 · Answer 5 · answered Dec 04 '18 at 16:56

A macro parameter can be a list of objects. The called macro can extract each object from the list, manipulate it, and then the caller will see the changes.

#macro(call $something)
  #set($swallowOutput = $something)
#end

#macro(doSomething $out)
  #set($list=$out.get(0))
  #call($list.add("hallo-1")
  #call($list.add("hallo-2")
#end

#macro(doMoreComplexStuff)
  #set($myList=[])
  #doSomething([$myList])
  MyList now has $myList.size()) elements: $myList
#end

score -1 · Answer 6 · edited Sep 13 '16 at 15:06

-1

Or just write everything onto the same line:

#macro( myMacro $param ) the_return_value #end

edited Sep 13 '16 at 15:06

Yasin Patel

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answered Sep 13 '16 at 14:25

François Bachmann

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Calling Macro function in Velocity template

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