Cannot pass an array type parameter in ARM template via Powershell

Question

I have an ARM Template with the following parameters:

"parameters": {
    "projectName": {
      "type": "string",
      "metadata": {
        "description": "Name of the project"
      }
    },
    "environmentName": {
      "type": "string",
      "defaultValue": "testing",
      "metadata": {
        "description": "Name/Type of the environment"
      }
    },
    "vmResourceGroupName": {
      "type": "string",
      "metadata": {
        "description": "Resource Group in which VMs wil be deployed"
      }
    },
    "vmName": {
      "type": "string",
      "metadata": {
        "description": "Name of the Virtual Machine"
      }
    },
    "vmIPAddress": {
      "type": "string",
      "metadata": {
        "description": "IP Address of the Virtual Machine"
      }
    },
    "osDiskVhdUri": {
      "type": "string",
      "metadata": {
        "description": "Uri of the existing VHD in ARM standard or premium storage"
      }
    },
    "dataDiskVhdUri": {
      "type": "array",
      "metadata": {
        "description": "Uri of the existing VHD in ARM standard or premium storage"
      }
    },
    "vmSize": {
      "type": "string",
      "metadata": {
        "description": "Size of the Virtual Machine"
      }
    },
    "osType": {
      "type": "string",
      "allowedValues": [
        "Windows",
        "Linux"
      ],
      "metadata": {
        "description": "OS of the VM - Typically Windows or Linux"
      }
    },
    "ManagedDisk": {
      "type": "string",
      "allowedValues": [
        "Yes",
        "No"
      ],
      "metadata": {
        "description":  "Yes for Managed Disks, No for VHDs"
      }
    }

As evident, $dataDiskVHDURI is of type:array and I am trying to deploy the template using -TemplateParameterObject with New-AzureRMresourceGroupDeployment cmdlet in Powershell using the following code:

{
        $vmWithDDTemplate = 'azuredeploy.json'
    $vmWithoutDDTemplate = 'azuredeploy-withoutdd.json'

    $dataDiskVhdUri = New-Object -TypeName System.Collections.ArrayList
    $dataDiskVhdUri.Add("$VM.dataDiskVhduri")


    #Creating VM param object    
    $VMTemplateObject = @{"projectname" = $projectName; `  
                          "environmentname" = $environmentName; `
                          "vmResourceGroupName" = $vmResourceGroupName; `
                          "vmName" = $VM.vmName; `
                          "vmIPAddress" = $VM.vmIPAddress; `
                          "osDiskVhdUri" = $VM.osDiskVhdUri; `
                          "dataDiskVhdUri" = ,$dataDiskVhdUri; `
                          "vmSize" = $VM.vmSize; `
                          "osType" = $VM.osType; `
                          "ManagedDisk" = $VM.ManagedDisk
                         }
    #$VMTemplateObject

    # Checking if VM contains a data disk
    if($VM.dataDiskVhdUri -ne $null) 
    {
        Write Output "$VM contains data disk"

        New-AzureRmResourceGroupDeployment -Name ('vmwithdd' + '-' + ((Get-Date).ToUniversalTime()).ToString('MMdd-HHmm')) `
                                   -ResourceGroupName $ResourceGroupName `
                                   -TemplateParameterObject $VMTemplateObject `
                                   -TemplateFile $vmWithDDTemplate `
                                    -Force -Verbose -ErrorVariable ErrorMessages `
                                    -ErrorAction Stop -DefaultProfile $azureCred

    }
    else
    {
        Write-output '$VM does not contain data disk'
    }
}

However, I get the following error every time:

Microsoft.PowerShell.Utility\Write-Error : 4:46:14 PM - Error: Code=InvalidTemplate; Message=Deployment template validation failed: 'The provided value for the template parameter 'dataDiskVhdUri' at line '44' and column '27' is not valid.'. At Create-Environment:73 char:73 + + CategoryInfo : NotSpecified: (:) [Write-Error], RemoteException + FullyQualifiedErrorId : System.Management.Automation.RemoteException,Microsoft.PowerShell.Commands.WriteErrorCommand + PSComputerName : [localhost]

Does anyone know how to resolve this?

Answer 1

Try this:

$OptionalParameters = New-Object -TypeName Hashtable

$OptionalParameters.Add("aParam", @(1,2,3))

New-AzureRmResourceGroupDeployment -ResourceGroupName $ResourceGroupName `
                                   -TemplateFile azuredeply.json `
                                   @OptionalParameters

With:

{
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
    "aParam": {
        "type": "array"
    }
},
"variables": { },
"resources": [ ],
"outputs": {
    "dump": {
        "type": "array",
        "value": "[parameters('aParam')]"
    }
}

}

Answer 2

Not sure, but maybe feeding it with an ArrayList object wrapped in an array by use of the preceeding , is not what it wants. If i lookup examples, i see only single values added there like "dataDiskVhdUri" = $VM.dataDiskVhduri;