A sample Azure DevOps YAML Pipeline to update WI based on a WIQL query

Update-WorkitemField.yml

# A pipeline to update a specific field in a work items that meeting a specific WIQL filter

# Do not trigger on a commit to the repo, but allow a manual run
trigger: none

# Run the pipeline at 1am every day
schedules:
- cron: '1 0 * * *'
  displayName: Daily midnight build
  always: true
  branches:
    include:
    - main

# Parameters to allow overiding values on a manual run 
parameters:
  - name: TrialRun
    displayName: Trial Run (Find the WI in scope but do not update)
    type: boolean
    default: false
  - name: FieldName
    displayName: Numeric WI Field to update
    type: string
    default: "Custom.PBIAge"
  - name: WIQL
    displayName: The WIQL Query to select the WI to update
    type: string
    default: "SELECT [System.Id] FROM workitems WHERE ([System.WorkItemType] = 'Bug' OR [System.WorkItemType] = 'Product Backlog Item' ) AND [System.State] IN ('Code Complete', 'Rework', 'Failed QA', 'Passed QA', 'Ready For Release QA', 'Failed Release QA', 'Passed Release QA', 'Ready To Deployed' )"

pool:
  vmImage: ubuntu-latest

steps:
- checkout: none
- task: PowerShell@2
  displayName: 'Increment PBI count'
  inputs:
    targetType: 'inline'
    pwsh: true
    script: |   
      # Set the values that would be passed in a parameters to a script
      $org = '$(System.TeamFoundationCollectionUri)'
      $project = "$(System.TeamProject)"
      $fieldName = "${{ parameters.FieldName }}"
      $query = "${{ parameters.WIQL}}"
      $trialRun = [System.Convert]::ToBoolean("${{parameters.TrialRun}}")

      # Append the project filter to the query so that only the required project is queried
      # if this is not done then the query will return all work items in the organisation that the user has access too
      # Note: On why this required
      #  - This has been done in this manner, as opposed to including it in the query string, as it was deemed this makes the query easier to understand
      #  - The --project parameter has not been used as this will not work with the --wiql parameter, the parameter overrides it.
      $query += " AND [System.TeamProject] = '$project'"
      write-host "Using the query '$query'"

      # Get the work items that match the query, and force into an array as PS will not return an array for a single item
      $workitems = @(az boards query --org $org --project $project --wiql $query | ConvertFrom-Json)
      write-host "Found $($workitems.Count) work items that match the query"

      # Loop across all the work items that match the query
      foreach ($wi in $workitems) {
          $id = $wi.id

          # Get the current value of the fieldName
          $currentWi = az boards work-item show --org $org --id $id | ConvertFrom-Json 
          $fieldValue = $currentWi.fields.$fieldName

          Write-Host "  Processing '$($currentWi.fields."System.WorkItemType")' WI #$id"

          # Check the fieldName is numeric and if the value is null set to zero
          if ($fieldValue -eq $null) {
              $fieldValue = 0
          } elseif ($fieldValue -isnot [double] -and $fieldValue -isnot [int64]) {  
              Write-Warning "The fieldName '$fieldName' does not contain numeric data'"
              continue
          }

          if ($trialRun) {
            write-host "    TRIALRUN: The current value of the fieldName '$fieldName' would be updated from $fieldValue to $($fieldValue+1)"

          } else {
            write-host "    The current value of the fieldName '$fieldName' will be updated from $fieldValue to $($fieldValue+1)"

            $updatedWi =  az boards work-item update --org $org --id $id --fields "$fieldName=$($fieldValue+1)" | ConvertFrom-Json

            # error if the field was not updated
            if ($updatedWi.fields.$fieldName -ne $fieldValue+1) {
                Write-Host "The fieldName '$fieldName' was not updated to $($fieldValue+1) "
                exit 1
            }
          }
      }
      Write-Host "All work items have been updated"
  env:
    AZURE_DEVOPS_EXT_PAT: $(System.AccessToken)