Split string in a foreach-object loop

Question

I'm preparing a report for disks in Azure and I want to include a VM name onto which disk is assigned. I found a property called managedby in get-azurermdisk cmdlet, but it represent a whole directory, not the VM name only (which is included at the very end). I want to split a whole string by '/' and want to leave only the very last part of property.

This is the script i prepared:

$DISK = Get-AzureRmDisk

$Output = $DISK | ForEach-Object {
[PSCustomObject]@{
"Name" = $_.Name
"Resource Group Name" =$_.ResourceGroupName
"Disk Tier" = $_.Sku.Tier
"Disk Type" = $_.Sku.Name
"Managed By" = $_.ManagedBy
"Time Created" = $_.TimeCreated
"Disk Size (in GB)" = $_.DiskSizeGB
"I/O per second" = $_.DiskIOPSReadWrite
"MBps per second" = $_.DiskMBpsReadWrite
"Location" = $_.Location
}
}

I already tried to do split:

"Managed By" = ($_.ManagedBy).Split('/')[8]

And separate loops to fill the "Managed By" column:

foreach($dsk in $dsks){
    $vm = $DISK | Where-Object -Property id -EQ $dsk.Name
    $prv = $dsk.ManagedBy.Split('/')[6]
    $managed.Add($vm.Name,$prv)
}

foreach($vm in $Output)
{
    if($ips.ContainsKey($vm."Name"))
    {
        $vm."Managed By"=$ips[$vm."Managed By"]
    }
}

Error:

You cannot call a method on a null-valued expression.

How can I add a some kind of ignore when value is null statement?

Answer 1

The error means that the ManagedBy is null when you try to split on it.

Just add if else for ManagedBy in this code block $Output = $DISK | ForEach-Object{},

like below:

$Output = $DISK | ForEach-Object {
[PSCustomObject]@{
"Name" = $_.Name
"Resource Group Name" =$_.ResourceGroupName
"Disk Tier" = $_.Sku.Tier
"Disk Type" = $_.Sku.Name
"Managed By" = if($_.ManagedBy){$_.ManagedBy.Remove(0,$_.ManagedBy.LastIndexOf('/')+1)}else{"none"}
"Time Created" = $_.TimeCreated
"Disk Size (in GB)" = $_.DiskSizeGB
"I/O per second" = $_.DiskIOPSReadWrite
"MBps per second" = $_.DiskMBpsReadWrite
"Location" = $_.Location
}
}

I write a sample code and test result as blow, you can just make some changes to meet your need: