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· Jul 8

Using Variables in Foreach within Rules

#Business Rules #HealthShare #InterSystems IRIS for Health #Health Connect

Hi Community

I'm working on a complex piece of rules that needs to check each OBX and evaluate if 3 of the fields match certain criteria. I've tried to achieve this using a Foreach loop, which does work, however it is not as clean as I wanted it. I was hoping I could assign temp variables inside the foreach loop to make the rules more easier to read, for example @testCode @resultText. This is not support as you can only assign inside a when condition. Before I raise this as an idea, i wondered if there was an alternative way to achieve the same thing?

Product version: IRIS 2024.1
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DC AI Bot · Jul 8

To assign temporary variables within a foreach loop in ObjectScript, you may consider alternatives that enhance readability and maintainability:

  1. Using Macros for foreach Iteration:
    You can define and use macros for looping over arrays and performing actions on each element. A macro can abstract the repetitive code required for array traversal. For example:

    ##; Macro definitions
#define foreach(%key,%arr,%do) set %key="" for  set %key=$o(%arr(%key)) q:%key=""  do %do

    Example usage:

    #include ZFOREACHMACRO
test $$$foreach(key,^rcc,show)
   quit
show zwrite @$zr,!
   quit

    This approach simplifies the loop logic and makes it more modular [1][2].

  2. Extended Command:
    Another option is creating an extended command ZZFOREACH for iteration. This allows deployment across namespaces and provides flexibility such as starting at a specific subscript or reversing the direction. Example command definition:

    ZZFOREACH(%par) public {
   set %par=$lfs(%par,";")
   new %array,%do,%fwd,%key,%val
   set %array=$lg(%par,1),%do=$lg(%par,2),%fwd=$lg(%par,3),%key=$lg(%par,4)
   if '%fwd set %fwd=1
   if %key]"" set %key=$o(@%array@(%key),$s(%fwd<1:-1,1:1))
   for  set %key=$o(@%array@(%key),%fwd,%val) quit:%key=""  do @%do
   quit 1
}

    Example usage:

    DEMO>zzforeach "^rcc;show^dump(%array,%key,%val)"
^rcc(1) = 1
^rcc(2) = 2
^rcc(3) = 3
^rcc(4) = 4
^rcc(5) = 5

    This method condenses the loop logic and embeds control features [1][2].

  3. Using the ObjectScript foreach Library:
    ObjectScript libraries such as the one in Foreach's GitHub repository enable modular iteration. The library supports dynamic arrays, objects, and other constructs. The syntax for using this is as follows:

    USER>set YOUR_VARIABLE = ["sample","data"]
USER>do ##class(Iteration.Loop).Foreach(YOUR_VARIABLE,"METHODNAME")

    Inside the method (METHODNAME), actions for each element can be defined:

    ClassMethod METHODNAME(pMes) As %Status {
   write pMes, !
   return $$$OK
}

    This library provides flexibility for defining custom methods for element handling [3].

These solutions provide alternatives to for-each loops in ObjectScript that improve code readability and may allow variable assignments during iterations, adhering to your goal [1][3][2].

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