Parameter validation in PowerShell - Cheat Sheet & Quick Revision

Recall & Review

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What is parameter validation in PowerShell functions?

Parameter validation ensures that the inputs to a function meet specific rules before the function runs. It helps catch errors early and makes scripts more reliable.

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How do you enforce that a parameter must not be empty in PowerShell?

Use the [ValidateNotNullOrEmpty()] attribute before the parameter. It stops the function if the parameter is null or an empty string.

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What does the [ValidateRange(min, max)] attribute do?

It checks that a numeric parameter is within the specified minimum and maximum values. If the input is outside this range, PowerShell throws an error.

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How can you restrict a parameter to accept only specific values?

Use the [ValidateSet('value1', 'value2', ...)] attribute. This limits the parameter to only those listed values, helping avoid typos or invalid inputs.

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What happens if a parameter fails validation in PowerShell?

PowerShell stops running the function and shows an error message explaining which validation rule was broken. This prevents the function from running with bad input.

Which attribute ensures a parameter is not null or empty in PowerShell?

A [ValidateNotNullOrEmpty()]

B [ValidateRange()]

C [ValidateSet()]

D [ValidateLength()]

The [ValidateNotNullOrEmpty()] attribute checks that the parameter is neither null nor an empty string.

What does [ValidateSet('Red','Green','Blue')] do for a parameter?

A Sets a default value for the parameter

B Checks if the parameter is a number

C Ensures the parameter is not empty

D Limits the parameter to only 'Red', 'Green', or 'Blue'

It restricts the parameter to accept only the specified values 'Red', 'Green', or 'Blue'.

If a parameter has [ValidateRange(1,10)], what happens if you pass 15?

A The function runs normally

B The parameter is set to 10 automatically

C PowerShell throws a validation error

D The parameter is ignored

Passing a value outside the range causes PowerShell to throw a validation error and stop the function.

Which attribute would you use to ensure a string parameter is not empty?

A [ValidatePattern()]

B [ValidateNotNullOrEmpty()]

C [ValidateSet()]

D [ValidateRange()]

Use [ValidateNotNullOrEmpty()] to ensure the string parameter is not empty or null.

What is the main benefit of parameter validation in scripts?

A It prevents invalid inputs and errors early

B It makes scripts run faster

C It hides errors from users

D It automatically fixes input mistakes

Parameter validation helps catch bad inputs early, preventing errors during script execution.

Explain how to use parameter validation attributes in a PowerShell function and why they are useful.

Think about how you can stop a function from running if the input is wrong.

Describe what happens when a parameter fails validation in PowerShell and how it affects the function execution.

Consider what PowerShell does to protect your script from bad inputs.