Azure DevOps - Pass Powershell list variable to yml template array - powershell

Question

I want to generate a list in a Powershell task as an output variable and use it in a yml template as a list to perform a loop for a task.
#Main
- task: PowerShell#2
condition: succeeded()
displayName: "Create a list"
inputs:
targetType: 'inline'
script: |
$myList = New-Object System.Collections.ArrayList
$myList.Add("wow")
Write-Output ("##vso[task.setvariable variable=MyList;]$myList")
- template: myRandomListTaskTemplate.yml
parameters:
MyList: $(MyList)
#Template
parameters:
MyList: []
steps:
- ${{ each myList in parameters.MyList }}:
- task: PowerShell#2
condition: succeeded()
displayName: "WOW a list"
inputs:
targetType: 'inline'
script: |
Write-Host("A list string: ${{ myList }}")
I am getting the error
Expected a sequence or mapping. Actual value '$(MyList)'
Note: The Powershell Task in the Template is just an example, it can be other Tasks that are not Powershell related (example: DotNetCoreCLI#2)

Answer 1

It will not work as you expect.
$myList = New-Object System.Collections.ArrayList
$myList.Add("wow")
Write-Output ("##vso[task.setvariable variable=MyList;]$myList")
You are not going here to have an array. Once you assign this to variable it will be a plain string. This is why you are getting this error.
If you run this:
- template: myRandomListTaskTemplate2.yml
parameters:
MyList:
- item1
- item2
all went fine. However, it is not possible to do what you at the moment.
Please check this developer community topic.