JSON operations (ConvertFrom-Json, ConvertTo-Json) in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this PowerShell command?

Given this JSON string and command, what will be the output?

PowerShell

$json = '{"name":"Alice","age":30}'; $obj = $json | ConvertFrom-Json; $obj.name

A {name=Alice; age=30}

B Alice

C 30

D System.Object

💡 Hint

ConvertFrom-Json turns JSON text into an object you can access properties from.

The ConvertFrom-Json cmdlet converts the JSON string into an object. Accessing $obj.name returns the string 'Alice'.

💻 Command Output

intermediate

What does this command output?

What is the output of this PowerShell command?

PowerShell

$obj = @{name='Bob'; age=25}; $json = $obj | ConvertTo-Json; $json

A

{
  "name": "Bob",
  "age": 25
}

B name=Bob age=25

C System.String

D {"name":"Bob","age":25}

💡 Hint

ConvertTo-Json formats the object as a JSON string with indentation.

ConvertTo-Json outputs a formatted JSON string with properties and values. It includes indentation and quotes.

📝 Syntax

advanced

Which option correctly parses nested JSON and accesses a nested property?

Given this JSON string, which command correctly outputs the city name?

PowerShell

$json = '{"person":{"name":"Eve","address":{"city":"Seattle","zip":"98101"}}}';

A $obj = ConvertFrom-Json $json; $obj.person.address.city

B $obj = $json | ConvertFrom-Json; $obj['person']['address']['city']

C $obj = $json | ConvertFrom-Json; $obj.person.address.city

D $obj = $json | ConvertTo-Json; $obj.person.address.city

💡 Hint

ConvertFrom-Json converts JSON text to an object. Use dot notation to access nested properties.

Option C correctly pipes the JSON string to ConvertFrom-Json and accesses nested properties with dots. Option C is invalid syntax. Option C uses ConvertTo-Json which converts objects to JSON, not parsing. Option C uses array syntax which is invalid for PSCustomObject.

🔧 Debug

advanced

Why does this command fail to output the expected JSON string?

This PowerShell code is intended to convert an object to JSON and print it, but it outputs nothing. What is the problem?

PowerShell

$obj = @{fruit='apple'; color='red'}; ConvertTo-Json $obj

A The command outputs JSON but it is not captured or printed explicitly.

B ConvertTo-Json cannot convert hashtables directly.

C The variable $obj is empty, so no output is produced.

D ConvertTo-Json requires the -Compress flag to output anything.

💡 Hint

In PowerShell, commands output to the pipeline but may not display if not captured or printed.

ConvertTo-Json outputs JSON to the pipeline, but if the output is not assigned or printed, it may not appear. Using Write-Output or assigning to a variable and then printing fixes this.

🚀 Application

expert

How many items are in the resulting array after this JSON conversion?

Given this JSON string representing an array, how many elements does the PowerShell object contain after conversion?

PowerShell

$json = '[{"id":1,"val":"a"},{"id":2,"val":"b"},{"id":3,"val":"c"}]'; $arr = $json | ConvertFrom-Json; $arr.Count

A Throws an error

B 1

C 0

D 3

💡 Hint

ConvertFrom-Json converts JSON arrays into PowerShell arrays with Count property.

The JSON string is an array of 3 objects. After conversion, $arr is a PowerShell array with 3 elements, so $arr.Count is 3.