Parameter validation in PowerShell - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to validate that the parameter $Age is an integer.

PowerShell

param([[1]]$Age)
Write-Output "Age is $Age"

Drag options to blanks, or click blank then click option'

Aint

Bstring

Cbool

Darray

Attempts:

3 left

💡 Hint

Common Mistakes

Using [string] instead of [int] allows any text, not just numbers.

Using [bool] or [array] does not match the expected integer type.

The [int] type validates that the parameter is an integer.

2fill in blank

medium

Complete the code to validate that the parameter $Name is mandatory.

PowerShell

param(
    [Parameter([1]=$true)]
    [string]$Name
)
Write-Output "Name is $Name"

Drag options to blanks, or click blank then click option'

APosition

BOptional

CMandatory

DValueFromPipeline

Attempts:

3 left

💡 Hint

Common Mistakes

Using Optional instead of Mandatory allows skipping the parameter.

Using Position or ValueFromPipeline does not enforce requirement.

The 'Mandatory' attribute makes the parameter required.

3fill in blank

hard

Fix the error in the code to validate that $Score is between 0 and 100.

PowerShell

param(
    [ValidateRange([1], 100)]
    [int]$Score
)
Write-Output "Score is $Score"

Drag options to blanks, or click blank then click option'

A1

B100

C-1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 as minimum excludes 0 which may be valid.

Using -1 allows negative scores which are invalid.

Using 100 as minimum is incorrect because max must be >= min.

The ValidateRange attribute requires the minimum value first, which is 0.

4fill in blank

hard

Fill in the blank to validate that $Color is one of the allowed values.

PowerShell

param(
    [ValidateSet([1])]
    [string]$Color
)
Write-Output "Color is $Color"

Drag options to blanks, or click blank then click option'

A'Red', 'Green', 'Blue'

B'Yellow', 'Purple', 'Orange'

C'Circle', 'Square', 'Triangle'

D'Cat', 'Dog', 'Bird'

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated sets like shapes or animals.

Not using quotes around the values.

ValidateSet restricts the parameter to the specified values: Red, Green, Blue.

5fill in blank

hard

Fill all three blanks to validate $Count is an integer between 1 and 10 and mandatory.

PowerShell

param(
    [Parameter([1]=$true)]
    [ValidateRange([2], [3])]
    [int]$Count
)
Write-Output "Count is $Count"

Drag options to blanks, or click blank then click option'

AMandatory

B1

C10

DOptional

Attempts:

3 left

💡 Hint

Common Mistakes

Setting Mandatory to false or Optional allows skipping the parameter.

Using wrong range values like 0 or 11.

The parameter is mandatory and must be between 1 and 10 inclusive.

Practice

1. What is the main purpose of parameter validation in a PowerShell script?

easy

A. To speed up the script execution

B. To format the output of the script

C. To check input values before the script runs to avoid errors

D. To create new variables automatically

Solution

1. Step 1: Understand parameter validation role

   Parameter validation ensures inputs meet certain rules before the script runs.

2. Step 2: Identify the main benefit

   This prevents errors caused by bad inputs and makes scripts safer.

3. Final Answer:

   To check input values before the script runs to avoid errors -> Option C

4. Quick Check:

   Parameter validation = input checking [OK]

Hint: Validation checks inputs early to prevent errors [OK]

Common Mistakes:

• Thinking validation speeds up script
• Confusing validation with output formatting
• Assuming validation creates variables

2. Which of the following is the correct syntax to validate that a parameter only accepts values from a fixed set: 'Red', 'Green', or 'Blue'?

easy

A. [ValidateSet('Red','Green','Blue')] param([string]$Color)

B. [ValidateRange('Red','Green','Blue')] param([string]$Color)

C. [ValidateNotNullOrEmpty('Red','Green','Blue')] param([string]$Color)

D. [ValidatePattern('Red|Green|Blue')] param([string]$Color)

Solution

1. Step 1: Identify correct validation attribute for fixed sets

   [ValidateSet] restricts input to specific allowed values.

2. Step 2: Match syntax with attribute usage

   The syntax [ValidateSet('Red','Green','Blue')] is correct for this purpose.

3. Final Answer:

   [ValidateSet('Red','Green','Blue')] param([string]$Color) -> Option A

4. Quick Check:

   Fixed set validation = ValidateSet [OK]

Hint: Use ValidateSet for fixed allowed values [OK]

Common Mistakes:

• Using ValidateRange for strings
• Confusing ValidateNotNullOrEmpty with value restriction
• Using ValidatePattern incorrectly for sets

3. What will be the output of this script if called with -Age 25?

function Test-Age {
  param(
    [ValidateRange(18,30)]
    [int]$Age
  )
  "Age is $Age"
}
Test-Age -Age 25

medium

A. "Age is 18"

B. Error: Parameter validation failed

C. No output

D. "Age is 25"

Solution

1. Step 1: Check parameter validation range

   The parameter $Age must be between 18 and 30 inclusive.

2. Step 2: Verify input against range

   Input 25 is within the range, so validation passes and script runs.

3. Final Answer:

   "Age is 25" -> Option D

4. Quick Check:

   25 in 18-30 range = valid input [OK]

Hint: Check if input fits ValidateRange limits [OK]

Common Mistakes:

• Assuming validation fails for valid input
• Confusing output with error message
• Ignoring the inclusive range

4. Identify the error in this parameter validation code:

function Set-Name {
  param(
    [ValidateNotNullOrEmpty()]
    [string]$Name
  )
  "Name set to $Name"
}
Set-Name -Name $null

medium

A. The parameter type should be [int] instead of [string]

B. The function will throw a validation error because $Name is null

C. The ValidateNotNullOrEmpty attribute is used incorrectly without parameters

D. The function will accept null and print 'Name set to '

Solution

1. Step 1: Understand ValidateNotNullOrEmpty behavior

   This attribute rejects null or empty string inputs.

2. Step 2: Analyze input value

   The input is $null, which violates the validation rule, causing an error.

3. Final Answer:

   The function will throw a validation error because $Name is null -> Option B

4. Quick Check:

   Null input with ValidateNotNullOrEmpty = error [OK]

Hint: Null or empty inputs fail ValidateNotNullOrEmpty [OK]

Common Mistakes:

• Thinking null is accepted
• Assuming ValidateNotNullOrEmpty needs parameters
• Confusing parameter type requirements

5. You want to create a script parameter $Port that only accepts integers between 1024 and 65535 and cannot be empty. Which parameter validation attributes should you use together?

hard

A. [ValidateRange(1024,65535)][ValidateNotNullOrEmpty()]

B. [ValidateSet(1024,65535)][ValidateNotNullOrEmpty()]

C. [ValidatePattern('^[0-9]{4,5}$')]

D. [ValidateNotNullOrEmpty()][ValidateLength(4,5)]

Solution

1. Step 1: Choose attribute for numeric range

   [ValidateRange(1024,65535)] ensures the integer is within the port number range.

2. Step 2: Ensure parameter is not empty

   [ValidateNotNullOrEmpty()] prevents null or empty input.

3. Step 3: Combine both for full validation

   Using both attributes together enforces the correct range and non-empty input.

4. Final Answer:

   [ValidateRange(1024,65535)][ValidateNotNullOrEmpty()] -> Option A

5. Quick Check:

   Range + NotNullOrEmpty = correct port validation [OK]

Hint: Combine ValidateRange and ValidateNotNullOrEmpty for numeric required input [OK]

Common Mistakes:

• Using ValidateSet for numeric ranges
• Relying on ValidatePattern for numeric range checks
• Missing non-empty validation