JSON operations (ConvertFrom-Json, ConvertTo-Json) in PowerShell - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the PowerShell cmdlet <code>ConvertFrom-Json</code> do?

It takes a JSON string and turns it into PowerShell objects you can work with easily.

beginner

What is the purpose of ConvertTo-Json in PowerShell?

It converts PowerShell objects into a JSON string format, which can be saved or sent to other programs.

beginner

How would you convert a JSON string stored in a variable $jsonString to a PowerShell object?

Use $obj = $jsonString | ConvertFrom-Json to get a PowerShell object from the JSON string.

beginner

How can you convert a PowerShell object $obj back to a JSON string?

Use $jsonString = $obj | ConvertTo-Json to get a JSON string from the object.

beginner

Why is JSON useful in scripting and automation?

JSON is a simple text format to share data between programs and scripts, making automation easier and more flexible.

Which cmdlet converts a JSON string into a PowerShell object?

A ConvertTo-Json

B ConvertFrom-Xml

C ConvertTo-Xml

D ConvertFrom-Json

ConvertFrom-Json takes JSON text and creates PowerShell objects.

What does ConvertTo-Json output?

A JSON string

B XML string

C PowerShell objects

D CSV string

ConvertTo-Json turns objects into JSON text format.

If you want to send data from PowerShell to a web API, which cmdlet helps prepare the data?

A ConvertFrom-Json

B ConvertTo-Json

C Invoke-WebRequest

D Get-Content

You use ConvertTo-Json to make your data a JSON string before sending it.

What type of data does ConvertFrom-Json produce?

A Plain text

B HTML code

C PowerShell objects

D Binary data

ConvertFrom-Json creates PowerShell objects from JSON text.

Which of these is a correct way to convert JSON text stored in $json to an object?

A $json | ConvertFrom-Json

B $json | ConvertTo-Json

C ConvertTo-Json $json

D ConvertFrom-Json -InputObject $json

The pipe | sends the JSON string to ConvertFrom-Json to get an object.

Explain how you would convert a JSON string to a PowerShell object and then back to JSON.

Think about the flow: JSON string → object → JSON string

Why is JSON a popular format for scripting and automation tasks?

Consider why scripts often use JSON to talk to other programs or APIs

Practice

1. What does the PowerShell cmdlet ConvertFrom-Json do?

easy

A. It converts JSON text into PowerShell objects.

B. It converts PowerShell objects into JSON text.

C. It formats JSON text for better readability.

D. It validates JSON syntax without conversion.

Solution

1. Step 1: Understand the purpose of ConvertFrom-Json

   This cmdlet takes JSON formatted text and turns it into PowerShell objects you can work with.

2. Step 2: Differentiate from ConvertTo-Json

   ConvertTo-Json does the opposite by turning objects into JSON text, so it is not the correct answer here.

3. Final Answer:

   It converts JSON text into PowerShell objects. -> Option A

4. Quick Check:

   ConvertFrom-Json = JSON text to objects [OK]

Hint: ConvertFrom-Json = JSON text to objects [OK]

Common Mistakes:

• Confusing ConvertFrom-Json with ConvertTo-Json
• Thinking it only formats JSON without conversion
• Assuming it validates JSON syntax only

2. Which of the following is the correct syntax to convert a JSON string stored in variable $jsonText into a PowerShell object?

easy

A. ConvertTo-Json $jsonText

B. $jsonText | ConvertTo-Json

C. ConvertFrom-Json $jsonText -Compress

D. $jsonText | ConvertFrom-Json

Solution

1. Step 1: Identify the correct cmdlet for JSON to object conversion

   ConvertFrom-Json converts JSON text to PowerShell objects, so it is the right cmdlet.

2. Step 2: Check the syntax for using pipeline

   Using $jsonText | ConvertFrom-Json is the correct way to pipe the JSON string into the cmdlet.

3. Final Answer:

   $jsonText | ConvertFrom-Json -> Option D

4. Quick Check:

   Pipe JSON string to ConvertFrom-Json [OK]

Hint: Pipe JSON string to ConvertFrom-Json for conversion [OK]

Common Mistakes:

• Using ConvertTo-Json instead of ConvertFrom-Json
• Trying to call ConvertFrom-Json without pipeline incorrectly
• Confusing parameter order or cmdlet usage

3. What is the output of this PowerShell code?

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

medium

A. Error: Cannot convert string to object

B. 30

C. age

D. "30"

Solution

1. Step 1: Convert JSON string to object

   The JSON string contains a property "age" with value 30 (number). ConvertFrom-Json creates an object with property age = 30.

2. Step 2: Access the age property

   Accessing $obj.age returns the numeric value 30, not a string or error.

3. Final Answer:

   30 -> Option B

4. Quick Check:

   Property age value = 30 [OK]

Hint: ConvertFrom-Json creates objects; access properties directly [OK]

Common Mistakes:

• Expecting age as a string with quotes
• Thinking the output is the property name 'age'
• Assuming conversion error occurs

4. What is the output of this PowerShell code?

$json = '{"name":"Bob","age":25}'
$obj = ConvertFrom-Json $json
Write-Output $obj.name

medium

A. Bob

B. "Bob"

C. name

D. Error: Cannot convert string to object

Solution

1. Step 1: Convert JSON string to object

   The JSON string contains a property "name" with value Bob (string). ConvertFrom-Json creates an object with property name = Bob.

2. Step 2: Access the name property

   Accessing $obj.name returns the string value Bob, not a quoted string or error.

3. Final Answer:

   Bob -> Option A

4. Quick Check:

   Property name value = Bob [OK]

Hint: ConvertFrom-Json creates objects; access properties directly [OK]

Common Mistakes:

• Expecting output as a string with quotes
• Thinking the output is the property name 'name'
• Assuming positional argument causes conversion error

5. You have a PowerShell object:

$person = @{ Name = "Eve"; Age = 28; Skills = @("PowerShell", "JSON") }

Which command correctly converts this object to JSON text with indentation for readability?

hard

A. $person | ConvertTo-Json -Depth 2 -Compress

B. $person | ConvertTo-Json -Depth 2 -Pretty

C. $person | ConvertTo-Json -Depth 2

D. ConvertTo-Json $person -Depth 2 -Compress

Solution

1. Step 1: Understand ConvertTo-Json parameters

   ConvertTo-Json converts objects to JSON text. The -Depth parameter controls how deep nested objects are converted.

2. Step 2: Identify correct parameter for indentation

   By default, ConvertTo-Json outputs indented JSON. The -Compress parameter removes whitespace, so it is not desired. There is no -Pretty parameter.

3. Final Answer:

   $person | ConvertTo-Json -Depth 2 -> Option C

4. Quick Check:

   Default output is indented JSON [OK]

Hint: Use ConvertTo-Json with -Depth; default output is indented [OK]

Common Mistakes:

• Using -Compress removes indentation
• Using non-existent -Pretty parameter
• Not setting -Depth for nested objects