A PowerShell script to add a JSON object to a specified path within a JSON file.

Add-JsonObject.ps1

<#
.SYNOPSIS
Adds a JSON object to a specified path within a JSON file.

.DESCRIPTION
This script reads a JSON file, adds a specified JSON object to a given path within that file, and outputs the modified JSON.

.PARAMETER Path
The path to the JSON file.

.PARAMETER JSONText
The JSON text to add.

.PARAMETER JSONPath
The path within the JSON file where the object should be added.
If not supplied, the object will be added to the root of the JSON file.

.EXAMPLE
Add-JsonObject.ps1 .\global.json '{"test":{"runner": "Microsoft.Testing.Platform"}}'

#>
param(
	[Parameter(Mandatory = $true, Position = 0)]
	[string]$Path,
    
	[Parameter(Mandatory = $true, Position = 1)]
	[string]$JSONText,

	[string]$JSONPath = ""
)

$rootObject = Get-Content -LiteralPath $Path -Raw | ConvertFrom-Json;
$jsonObject = $JSONText | ConvertFrom-Json;

$targetValue = $rootObject;

$children = $JSONPath.Split('.');

$JSONPath.Split('.') | ForEach-Object { if([string]::IsNullOrEmpty($_) -eq $false) { $targetValue = $targetValue.$_ } }

Write-Verbose "Adding property '$($jsonObject.PSObject.Properties.Name)' with value $($jsonObject.PSObject.Properties.Value)";

$result = $targetValue | Add-Member -Type NoteProperty -Name $jsonObject.PSObject.Properties.Name -Value $jsonObject.PSObject.Properties.Value -Force;

$rootObject | ConvertTo-Json;