Document how to invoke DSC Resources with complex properties in v1.1

[michaeltlombardi]

Prerequisites

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Version

v1.1

Links

• https://learn.microsoft.com/en-us/powershell/dsc/managing-nodes/directcallresource?view=dsc-1.1

Summary

When a user wants to invoke a DSC Resource that has complex properties in PSDSCv1.1, they need to convert the complex property into a CimInstance or the invocation errors confusingly.

Details

With the example resource definition:

[DscResource()]
class InvocableExample {
  [DscProperty(Key)] [string]      $Path
  [DscProperty()]    [Complex]     $Info
  [DscProperty()]    [VeryComplex] $Options

  [InvocableExample] Get()  { return $this }
  [bool]             Test() { return $true }
  [void]             Set()  { }
}

class Complex {
    [DscProperty()] [string] $Version
    [DscProperty()] [bool]   $StartOnBoot
}

class VeryComplex {
  [DscProperty()] [string]   $Name
  [DscProperty()] [Nested[]] $Settings
}

class Nested {
  [DscProperty()] [bool]   $Enabled
  [DscProperty()] [string] $Name
}

You can use New-CimInstance with the ClientOnly parameter to create the complex property inline for the DSC Resource's property hash:

Invoke-DscResource -Name InvocableExample -Method Get -ModuleName ExampleResources -Property @{
  Path = 'C:\dsc\example.json'
  Info = New-CimInstance -ClientOnly -ClassName Complex -Property @{
    Version = '1.1.0'
  }
}

When the property's type is an array, like [Nested[]], you need to cast the inline array to [CimInstance[]]:

$Options = New-CimInstance -ClientOnly -ClassName VeryComplex -Property @{
    Name = 'Nested Options'
    Settings = New-CimInstance -ClientOnly Nested -Property [CimInstance[]]@(
        @{ Name = 'First'  ; Enabled = $true  }
        @{ Name = 'Second' ; Enabled = $false }
    )
}

You need to convert every complex property, including nested ones, with New-CimInstance.

Suggested Fix

Extend the documentation for invoking DSC Resources in v1.1 to document this requirement.