How to Read JSON File into Array in PowerShell?

JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate. In this PowerShell tutorial, I will explain how to read a JSON file into an array in PowerShell.

To read a JSON file into an array in PowerShell, use the Get-Content cmdlet to retrieve the file content and pipe it to the ConvertFrom-Json cmdlet. For example, $array = Get-Content -Path ‘file.json’ | ConvertFrom-Json will parse the JSON file into a PowerShell array if the JSON is an array format.

Table of Contents

Understanding JSON

Before we dive into PowerShell, let’s understand the structure of a JSON file. A JSON file typically consists of key-value pairs in a structured format. It can contain objects (denoted by curly braces {}) and arrays (denoted by square brackets []). Here’s a simple example of a JSON file:

{
  "users": [
    {"name": "John", "age": 30},
    {"name": "Jane", "age": 25},
    {"name": "Doe", "age": 22}
  ]
}

In this example, users is an array of objects, each containing a name and an age.

Reading JSON into PowerShell Array

To read JSON data into an array in PowerShell, we use the ConvertFrom-Json cmdlet, which converts JSON formatted strings to PowerShell objects.

Method 1: Using Get-Content and ConvertFrom-Json

The most common approach to read a JSON file into an array in PowerShell is to use Get-Content to get the file’s content and then pipe it to ConvertFrom-Json.

Here’s a step-by-step example:

Save your JSON file. For this example, we’ll name it users.json.
Open PowerShell and enter the following command:

$jsonData = Get-Content -Path 'C:\Bijay\users.json' | ConvertFrom-Json

Now, $jsonData contains the JSON file’s content as a PowerShell object. To access the users array, you can simply use $jsonData.users.

$usersArray = $jsonData.users

You can loop through the array and access each user’s properties like so:

foreach ($user in $usersArray) {
  Write-Host "Name: $($user.name), Age: $($user.age)"
}

You can see the output after I executed the PowerShell script using VS code.

$jsonData = Get-Content -Path 'C:\Bijay\users.json' | ConvertFrom-Json
$usersArray = $jsonData.users
foreach ($user in $usersArray) {
    Write-Host "Name: $($user.name), Age: $($user.age)"
  }

Method 2: Using ConvertFrom-Json Directly

Another way to read a JSON file in PowerShell is to use ConvertFrom-Json directly with the -InputObject parameter.

$jsonContent = Get-Content -Path 'C:\path\to\your\users.json' -Raw
$jsonData = $jsonContent | ConvertFrom-Json

The -Raw parameter ensures that Get-Content reads the file as a single string, which is necessary for ConvertFrom-Json to parse the JSON structure properly.

Method 3: Handling JSON with Custom Objects

Sometimes, you might want to convert JSON data directly into custom PowerShell objects. This can be done by defining a class in PowerShell and then using ConvertFrom-Json to cast the JSON directly into objects of that class.

class User {
  [string]$name
  [int]$age
}

$jsonData = Get-Content -Path 'C:\path\to\your\users.json' | ConvertFrom-Json

$usersArray = @($jsonData.users | ForEach-Object {
  $_ | ConvertTo-Json | ConvertFrom-Json -As [User]
})

In this example, ConvertTo-Json is used to convert each user to a JSON string, which is then piped to ConvertFrom-Json with the -As parameter specifying the custom class User.

Tips:

Always use the -Raw parameter with Get-Content when reading JSON files to ensure the entire file is read as a single string.
Use Write-Host or Write-Output to print the contents of the array to the console for debugging.
PowerShell is case-insensitive, but JSON keys are case-sensitive. Make sure to match the case when referring to JSON keys.
Validate your JSON file with a JSON validator to ensure it’s correctly formatted before trying to parse it with PowerShell.

Conclusion

Reading JSON data into an array in PowerShell is a straightforward process. Whether you’re using Get-Content and ConvertFrom-Json together or handling JSON data with custom objects, PowerShell provides the flexibility to work with JSON files.

In this PowerShell tutorial, I have explained how to read a JSON file into an array in PowerShell