Set Azure DevOps pipeline variable to array of values - powershell

Question

I am trying to run a set of tests across a set of ADO builds.
I can retrieve the list of ADO builds using PowerShell. However, once I have the list, I need to export that to an ADO variable and then iterate across the values.
I've seen how to export values from Powershell to ADO using logging, but that appears to export the value as a string, not a list.
Is there a way to export variables so that I could iterate across them; e.g., using ${{ each foo in exportedVars }}?

Answer 1

First, for the usage you mentioned:
${{ each foo in exportedVars }}
This is a compile-time usage, it is expanded at the beginning, and you can't get the variables generated by the pipeline runtime through it.
Second, the pipeline can output variables through the logging command, but the variables set in this way can only be strings. This is by design, and the documentation has said it very clearly:
https://learn.microsoft.com/en-us/azure/devops/pipelines/process/variables?view=azure-devops&tabs=yaml%2Cbatch#set-variables-in-scripts
All variables set by this method are treated as strings.
It is not difficult to parse a string and put it into an array, just use the function(split()) that comes with the string type to split and restore.
Here is an example:
trigger:
- none
# 1
stages:
- stage: s1
displayName: setvars
jobs:
- job: testJob
steps:
- task: PowerShell#2
name: setvar
inputs:
targetType: 'inline'
script: |
# logic here. For example you get the vars and put it into this format:
$testvars = "testvar1,testvar2,testvar3"
Write-Host "##vso[task.setvariable variable=outputvars;isOutput=true]$testvars"
# 2
- stage: s2
displayName: getvars
dependsOn: s1
variables:
vars: $[ stageDependencies.s1.testJob.outputs['setvar.outputvars'] ]
jobs:
- job:
steps:
- task: PowerShell#2
inputs:
targetType: 'inline'
script: |
$varsArr = "$(vars)".Split(',')
foreach ($var in $varsArr)
{
Write-Host "$var`r`n"
}
Result: