Chapter 9: Working with Objects

Discover how to use PowerShell�s object-oriented nature, working with properties and methods, and manipulating objects to handle data more effectively.

PowerShell is an object-oriented scripting language, which means it works with objects rather than plain text. This approach allows you to interact with the properties and methods of objects, making data manipulation and retrieval more efficient. In this chapter, we�ll explore how to use and manipulate objects in PowerShell.

Understanding Objects, Properties, and Methods

In PowerShell, objects represent data with defined characteristics (properties) and actions (methods). Properties hold data about the object, while methods are functions that perform actions on or with the object.

$process = Get-Process -Name "explorer"
Write-Output "Process ID: $($process.Id)"
Write-Output "Process Name: $($process.Name)"

Here, Get-Process retrieves a Process object with properties like Id and Name, which you can access to learn more about the process.

Viewing Object Properties and Methods with Get-Member

To see the properties and methods available for an object, use the Get-Member cmdlet. This cmdlet provides a list of all accessible members of an object:

$process = Get-Process -Name "explorer"
$process | Get-Member

This command lists all properties and methods for the Process object, including details like Id, HandleCount, and methods such as Kill().

Accessing Properties of Objects

You can access an object�s properties directly using the dot notation (object.property). For example:

$file = Get-Item -Path "C:\ExampleDir\example.txt"
Write-Output "File size: $($file.Length) bytes"
Write-Output "Last modified: $($file.LastWriteTime)"

This example accesses the Length and LastWriteTime properties of a file object, displaying its size and last modified date.

Calling Methods on Objects

Methods are actions that an object can perform. For example, the Process object has a Kill method to terminate a process:

$process = Get-Process -Name "notepad"
$process.Kill()

This command retrieves the notepad process and calls the Kill method to terminate it. Be cautious with methods like Kill(), as they can affect system operations.

Working with Object Arrays

PowerShell often returns multiple objects in an array. You can use loops or the pipeline to process each object individually:

$services = Get-Service

foreach ($service in $services) {
    Write-Output "$($service.DisplayName) - $($service.Status)"
}

This example retrieves all services and displays each service�s name and status.

Filtering Objects with Where-Object

The Where-Object cmdlet filters objects based on specified conditions, allowing you to narrow down results:

Get-Process | Where-Object { $_.CPU -gt 100 }

This command retrieves all processes and filters them to show only those with CPU usage greater than 100 units.

Selecting Specific Properties with Select-Object

The Select-Object cmdlet allows you to select specific properties from an object, which is useful for simplifying output:

Get-Process | Select-Object -Property Name, CPU

This command retrieves only the Name and CPU properties of each process, making the output more concise.

Sorting and Grouping Objects

PowerShell offers Sort-Object and Group-Object cmdlets for organizing data. Sort-Object arranges objects in a specified order, while Group-Object categorizes objects by a property:

# Sorting processes by CPU usage
Get-Process | Sort-Object -Property CPU -Descending

# Grouping services by status
Get-Service | Group-Object -Property Status

The first command sorts processes by CPU usage in descending order, while the second groups services by their current status.

Creating Custom Objects

You can create custom objects to store structured data in PowerShell. Custom objects allow you to define specific properties and values:

$person = [PSCustomObject]@{
    Name = "Alice"
    Age = 30
    Department = "Sales"
}

Write-Output "$($person.Name) works in $($person.Department)"

This example creates a custom object with properties for Name, Age, and Department, then outputs a sentence using those properties.

Summary and Next Steps

In this chapter, we covered the basics of working with objects in PowerShell, including accessing properties, calling methods, filtering and sorting objects, and creating custom objects. Understanding PowerShell�s object-oriented nature allows for more powerful and flexible scripts. In the next chapter, we�ll explore error handling and debugging techniques, helping you to manage and troubleshoot your scripts effectively.