PowerShell ConvertFrom-Json

last modified February 15, 2025

In this article, we will cover the ConvertFrom-Json cmdlet in PowerShell. This cmdlet converts JSON-formatted strings into PowerShell objects. It enables easy parsing and manipulation of JSON data in scripts.

JSON basics

JSON (JavaScript Object Notation) is a lightweight data interchange format. It uses human-readable text to store and transmit data objects. JSON represents data as key-value pairs and ordered lists. PowerShell can work with JSON data through the ConvertFrom-Json cmdlet.

Basic ConvertFrom-Json usage

The simplest way to use ConvertFrom-Json is with a JSON string. The cmdlet parses the string and returns a PowerShell object. This object can then be manipulated like any other PowerShell object. The JSON must be properly formatted.

json1.ps1

$json = '{"name":"John","age":30,"city":"New York"}'
$obj = $json | ConvertFrom-Json
$obj

This command converts a simple JSON string to a PowerShell object. The object properties can be accessed with dot notation. The output shows the parsed data.

Accessing JSON object properties

After converting JSON to an object, you can access its properties directly. Use dot notation to reference nested properties. This allows easy data extraction from complex JSON structures. Property names are case-sensitive.

json2.ps1

$json = '{"user":{"name":"Alice","email":"alice@example.com"}}'
$obj = $json | ConvertFrom-Json
$obj.user.name
$obj.user.email

This example shows how to access nested JSON properties. The user object contains name and email properties. These are accessed through dot notation.

Working with JSON arrays

JSON arrays are converted to PowerShell object arrays. You can iterate through them or access elements by index. Arrays maintain their order from the JSON source. This is useful for processing lists of items.

json3.ps1

$json = '["red","green","blue"]'
$colors = $json | ConvertFrom-Json
$colors[0]
$colors | ForEach-Object { "Color: $_" }

This example demonstrates working with a JSON array. The first element is accessed by index. Then all elements are processed in a loop.

Parsing complex JSON structures

ConvertFrom-Json can handle nested objects and arrays. Complex JSON structures become PowerShell objects with nested properties. This maintains the original data hierarchy. You can navigate through the structure with dot notation.

json4.ps1

$json = '{
  "employees": [
    {"name":"John", "skills":["PowerShell","C#"]},
    {"name":"Jane", "skills":["Python","SQL"]}
  ]
}'
$obj = $json | ConvertFrom-Json
$obj.employees[0].name
$obj.employees[1].skills[0]

This example parses a complex JSON structure. It contains an array of employee objects with nested skills arrays. Specific values are accessed through chained dot notation.

Reading JSON from a file

JSON data often comes from files. Use Get-Content to read the file first. Then pipe the content to ConvertFrom-Json. This is a common workflow for configuration files or API responses.

json5.ps1

$jsonContent = Get-Content -Path "config.json" -Raw
$config = $jsonContent | ConvertFrom-Json
$config.settings

This script reads JSON from a file and converts it to an object. The -Raw parameter ensures the entire file is read as a single string. The config object can then be used throughout the script.

Handling large JSON data

For large JSON files, use the -Depth parameter. It controls how many levels of nested objects are converted. The default depth is 1024. This prevents stack overflow errors with very deep structures.

json6.ps1

$bigJson = Get-Content -Path "large_data.json" -Raw
$data = $bigJson | ConvertFrom-Json -Depth 50
$data.items[0].details

This example shows how to process large JSON files. The -Depth parameter is set to handle deep nesting. The first item's details are then accessed.

Error handling with ConvertFrom-Json

Invalid JSON will cause parsing errors. Use try/catch blocks to handle these gracefully. This ensures your script can respond appropriately to malformed input. Always validate JSON data when possible.

json7.ps1

$badJson = '{"name": "Bob", "age": }'
try {
    $obj = $badJson | ConvertFrom-Json
    $obj
}
catch {
    Write-Host "Error parsing JSON: $_"
}

This example demonstrates error handling. The malformed JSON triggers an exception. The catch block displays a user-friendly error message.

Source

PowerShell documentation

In this article, we have covered the ConvertFrom-Json cmdlet in PowerShell.

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My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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