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Working with PowerShell Objects
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‎docs/learning-powershell/working-with-powershell-objects.md‎

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Working with PowerShell Objects
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====
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When cmdlets are executed in PowerShell, the output is an Object, as opposed to only returning text.
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This provides the ability to store information as properties.
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As a result, handling large amounts of data and getting only specific properties is a trivial task.
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As a simple example, the following function retrieves information about storage Devices on a Linux or MacOS operating system platform.
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This is accomplished by parsing the output of an existing command, *parted -l* in administrative context, and creating an object from the raw text by using the *New-Object* cmdlet.
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```PowerShell
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Function Get-DiskInfo {
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$disks = sudo parted -l | Select-String "Disk /dev/sd*" -context 1,0
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$diskinfo = @()
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foreach ($disk in $disks) {
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$diskline1 = $disk.ToString().Split("`n")[0].ToString().Replace(' Model: ','')
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$diskline2 = $disk.ToString().Split("`n")[1].ToString().Replace('> Disk ','')
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$i = New-Object psobject -Property @{'Friendly Name' = $diskline1; Device=$diskline2.Split(': ')[0]; 'Total Size'=$diskline2.Split(':')[1]}
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$diskinfo += $i
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}
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$diskinfo
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}
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```
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Execute the function and store the results as a variable.
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Now retrieve the value of the variable.
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The results are formatted as a table with the default view.
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*Note: in this example, the disks are virtual disks in a Microsoft Azure virtual machine.*
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```PowerShell
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PS /home/psuser> $d = Get-DiskInfo
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[sudo] password for psuser:
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PS /home/psuser> $d
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Friendly Name Total Size Device
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------------- ---------- ------
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Msft Virtual Disk (scsi) 31.5GB /dev/sda
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Msft Virtual Disk (scsi) 145GB /dev/sdb
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```
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Passing the variable down the pipeline to *Get-Member* reveals available methods and properties.
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This is because the value of *d$* is not just text output.
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The value is actually an array of .Net objects with methods and properties.
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The properties include Device, Friendly Name, and Total Size.
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```PowerShell
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PS /home/psuser> $d | Get-Member
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TypeName: System.Management.Automation.PSCustomObject
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Name MemberType Definition
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---- ---------- ----------
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Equals Method bool Equals(System.Object obj)
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GetHashCode Method int GetHashCode()
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GetType Method type GetType()
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ToString Method string ToString()
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Device NoteProperty string Device=/dev/sda
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Friendly Name NoteProperty string Friendly Name=Msft Virtual Disk (scsi)
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Total Size NoteProperty string Total Size= 31.5GB
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```
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To confirm, we can call the GetType() method interactively from the console.
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```PowerShell
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PS /home/psuser> $d.GetType()
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IsPublic IsSerial Name BaseType
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-------- -------- ---- --------
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True True Object[] System.Array
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```
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To index in to the array and return only specific objects, use the square brackets.
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```PowerShell
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PS /home/psuser> $d[0]
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Friendly Name Total Size Device
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------------- ---------- ------
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Msft Virtual Disk (scsi) 31.5GB /dev/sda
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PS /home/psuser> $d[0].GetType()
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IsPublic IsSerial Name BaseType
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-------- -------- ---- --------
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True False PSCustomObject System.Object
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```
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To return a specific property, the property name can be called interactively from the console.
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```PowerShell
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PS /home/psuser> $d.Device
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/dev/sda
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/dev/sdb
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```
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To output a view of the information other than default, such as a view with only specific properties selected, pass the value to the *Select-Object* cmdlet.
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```PowerShell
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PS /home/psuser> $d | Select-Object Device, 'Total Size'
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Device Total Size
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------ ----------
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/dev/sda 31.5GB
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/dev/sdb 145GB
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```
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Finally, the example below demonstrates use of the *ForEach-Object* cmdlet to iterate through the array and manipulate the value of a specific property of each object.
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In this case the Total Size property, which was given in Gigabytes, is changed to Megabytes.
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Alternatively, index in to a position in the array as shown below in the third example.
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```PowerShell
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PS /home/psuser> $d | ForEach-Object 'Total Size'
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31.5GB
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145GB
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PS /home/psuser> $d | ForEach-Object {$_.'Total Size' / 1MB}
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32256
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148480
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PS /home/psuser> $d[1].'Total Size' / 1MB
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148480
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```

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