Custom objects (PSCustomObject) in PowerShell - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a PSCustomObject in PowerShell?

A PSCustomObject is a way to create custom objects with properties and values in PowerShell. It helps organize data like a simple table or record.

beginner

How do you create a PSCustomObject with properties Name and Age?

Use the syntax:
$obj = [PSCustomObject]@{Name='Alice'; Age=30}
This creates an object with two properties: Name and Age.

intermediate

Why use PSCustomObject instead of a hashtable?

PSCustomObject lets you create objects that behave like real objects with properties, making it easier to work with in scripts and output. Hashtables are just key-value pairs without object behavior.

intermediate

How can you add a new property to an existing PSCustomObject?

You can add a property by using Add-Member cmdlet, for example:
$obj | Add-Member -NotePropertyName 'City' -NotePropertyValue 'Seattle'

beginner

What will this script output?
$person = [PSCustomObject]@{Name='Bob'; Age=25}
$person.Age = 26
$person

It outputs the object with updated Age property:
Name Age
---- ---
Bob 26
This shows you can change property values after creation.

Which syntax correctly creates a PSCustomObject with a property 'Color' set to 'Red'?

A $obj = @{Color='Red'}

B $obj = [Object]@{Color='Red'}

C $obj = New-Object Color='Red'

D $obj = [PSCustomObject]@{Color='Red'}

Option D uses the correct syntax to create a PSCustomObject with the property Color set to Red.

How do you add a new property 'Country' with value 'USA' to an existing PSCustomObject $obj?

A $obj.Country = 'USA'

B $obj.Add('Country','USA')

C $obj | Add-Member -NotePropertyName 'Country' -NotePropertyValue 'USA'

D You cannot add properties after creation

Both A (direct property assignment) and C (using the Add-Member cmdlet) correctly add a new property to a PSCustomObject.

What type of data structure is a PSCustomObject in PowerShell?

A A custom object with properties

B A key-value pair hashtable

C A simple string

D An array of values

PSCustomObject is a custom object that holds properties and values, not just key-value pairs.

Which command updates the 'Age' property of a PSCustomObject $person to 40?

A $person = @{Age=40}

B $person.Age = 40

C $person.Add('Age',40)

D $person | Set-Member -Name Age -Value 40

You can directly assign a new value to an existing property using $person.Age = 40.

What happens if you try to create a PSCustomObject without using [PSCustomObject] type accelerator?

A You get an empty object

B PowerShell throws an error

C You get a hashtable, not an object

D It creates a PSCustomObject anyway

Without [PSCustomObject], the syntax creates a hashtable, not a custom object.

Explain how to create a PSCustomObject with three properties and how to access one of those properties.

Think about how you write a hashtable and then convert it to an object.

Describe how to add a new property to an existing PSCustomObject and why this might be useful.

Remember you can modify objects after creation with a special cmdlet.

Practice

1. What is the main purpose of using [PSCustomObject] in PowerShell?

easy

A. To convert strings into numbers

B. To create objects with named properties for organizing related data

C. To create arrays of numbers automatically

D. To run commands faster in PowerShell

Solution

1. Step 1: Understand what [PSCustomObject] does

   [PSCustomObject] creates an object with named properties to hold related data clearly.

2. Step 2: Compare options

   Only "To create objects with named properties for organizing related data" correctly describes this purpose. Other options describe unrelated tasks.

3. Final Answer:

   To create objects with named properties for organizing related data -> Option B

4. Quick Check:

   Purpose of [PSCustomObject] = Organize data [OK]

Hint: Remember: [PSCustomObject] groups data with names [OK]

Common Mistakes:

• Thinking it speeds up command execution
• Confusing with arrays or type conversion
• Assuming it creates numeric sequences

2. Which of the following is the correct syntax to create a custom object with properties Name and Age in PowerShell?

easy

A. [PSCustomObject] @{Name: 'Alice'; Age: 30}

B. @{Name='Alice', Age=30} [PSCustomObject]

C. [PSCustomObject]@{Name='Alice'; Age=30}

D. [PSCustomObject]@{Name='Alice' Age=30}

Solution

1. Step 1: Recall correct syntax for custom object creation

   The correct syntax uses [PSCustomObject]@{PropertyName='Value'; PropertyName2=Value2} with semicolons separating properties.

2. Step 2: Analyze each option

   [PSCustomObject]@{Name='Alice'; Age=30} matches the correct syntax. @{Name='Alice', Age=30} [PSCustomObject] reverses order. [PSCustomObject] @{Name: 'Alice'; Age: 30} uses colons instead of equals. [PSCustomObject]@{Name='Alice' Age=30} misses semicolon between properties.

3. Final Answer:

   [PSCustomObject]@{Name='Alice'; Age=30} -> Option C

4. Quick Check:

   Correct syntax uses semicolons and equals [OK]

Hint: Use semicolons and equals inside @{ } with [PSCustomObject] [OK]

Common Mistakes:

• Using commas instead of semicolons
• Placing [PSCustomObject] after the hashtable
• Using colons instead of equals signs

3. What will be the output of this PowerShell code?

$person = [PSCustomObject]@{Name='Bob'; Age=25}; $person.Name

medium

A. Bob

B. 25

C. @{Name='Bob'; Age=25}

D. Name

Solution

1. Step 1: Understand object creation and property access

   The variable $person holds a custom object with properties Name and Age. Accessing $person.Name returns the value of the Name property.

2. Step 2: Determine the output

   The Name property was set to 'Bob', so the output is 'Bob'.

3. Final Answer:

   Bob -> Option A

4. Quick Check:

   Access property returns its value [OK]

Hint: Access properties with dot notation to get their values [OK]

Common Mistakes:

• Expecting the whole object printed
• Confusing property name with value
• Using wrong property name

4. Identify the error in this PowerShell code:

$obj = [PSCustomObject]@{Name='Eve' Age=28}

medium

A. Missing semicolon between properties inside the hashtable

B. Incorrect use of square brackets around PSCustomObject

C. Property names must be in double quotes

D. Cannot assign numbers as property values

Solution

1. Step 1: Check hashtable property separators

   Properties inside the hashtable must be separated by semicolons. Here, Name='Eve' and Age=28 are missing a semicolon between them.

2. Step 2: Verify other syntax elements

   Square brackets around PSCustomObject are correct. Property names do not require quotes. Numbers can be property values.

3. Final Answer:

   Missing semicolon between properties inside the hashtable -> Option A

4. Quick Check:

   Separate properties with semicolons [OK]

Hint: Separate each property with a semicolon inside @{ } [OK]

Common Mistakes:

• Using commas instead of semicolons
• Adding quotes around property names unnecessarily
• Thinking numbers can't be property values

5. You want to create a list of custom objects representing books with properties Title and Author. Which PowerShell code correctly creates an array of two such objects?

hard

A. [PSCustomObject]@{Title='1984', Author='Orwell'; Title='Dune', Author='Herbert'}

B. [PSCustomObject]@{Title='1984', Author='Orwell'}, [PSCustomObject]@{Title='Dune'; Author='Herbert'}

C. @{Title='1984'; Author='Orwell'}, @{Title='Dune'; Author='Herbert'}

D. @([PSCustomObject]@{Title='1984'; Author='Orwell'}, [PSCustomObject]@{Title='Dune'; Author='Herbert'})

Solution

1. Step 1: Understand how to create multiple custom objects in an array

   Each book must be a separate [PSCustomObject]. To create an array, wrap the objects in @( ) and separate them with commas.

2. Step 2: Analyze each option

   @([PSCustomObject]@{Title='1984'; Author='Orwell'}, [PSCustomObject]@{Title='Dune'; Author='Herbert'}) correctly creates two separate custom objects inside an array. [PSCustomObject]@{Title='1984', Author='Orwell'}, [PSCustomObject]@{Title='Dune'; Author='Herbert'} uses comma instead of semicolon in the first hashtable, causing a syntax error. @{Title='1984'; Author='Orwell'}, @{Title='Dune'; Author='Herbert'} creates hashtables, not custom objects. [PSCustomObject]@{Title='1984', Author='Orwell'; Title='Dune', Author='Herbert'} tries to combine two books in one object incorrectly.

3. Final Answer:

   @([PSCustomObject]@{Title='1984'; Author='Orwell'}, [PSCustomObject]@{Title='Dune'; Author='Herbert'}) -> Option D

4. Quick Check:

   Use array @( ) with separate custom objects [OK]

Hint: Wrap multiple [PSCustomObject]s in @( ) separated by commas [OK]

Common Mistakes:

• Using commas instead of semicolons inside hashtables
• Using hashtables instead of custom objects
• Combining multiple items in one object incorrectly