ConvertFrom-JSON strips array from object - json

Question

I'm loading a text file containing some Json to edit a property. However, after modifying the content and writing it to file, the Json becomes invalid.I
I use the following PowerShell to modify the file:
$manifest = Get-Content $PathToManifest -Raw | ConvertFrom-Json
#modify Json
Set-Content -Path $PathToManifest -Value ( $manifest | ConvertTo-Json)
The following snippet from my Json file gets corrupted:
"contributions": [
{
"id": "sample-data-widget",
"type": "ms.vss-dashboards-web.widget",
"targets": ["ms.vss-dashboards-web.widget-catalog"],
"properties": "#{name=Sample Data; description=Create sample data in a VSTS project.; previewImageUrl=img/logo.png; uri=index.html; supportedSizes=System.Object[]; supportedScopes=System.Object[]}"
}]
After loading the Json and writing it back to file the array syntax around targets is gone:
"contributions": [
{
"id": "sample-data-widget",
"type": "ms.vss-dashboards-web.widget",
"targets": "ms.vss-dashboards-web.widget-catalog",
"properties": "#{name=Sample Data; description=Create sample data in a VSTS project.; previewImageUrl=img/logo.png; uri=index.html; supportedSizes=System.Object[]; supportedScopes=System.Object[]}"
}]
Why is this happening? Is there a way to make sure the syntax doesn't change?

Answer 1

ConvertTo-Json has Depth parameter that controls how many levels of contained objects are included in the JSON representation. The default value is 2. ConvertTo-Json will call .ToString() on anything nested deeper than specified Depth.
So all you need is to specify sufficiently large number for Depth argument or just ([int]::MaxValue).
Set-Content -Path $PathToManifest -Value ( $manifest | ConvertTo-Json -Depth ([int]::MaxValue))
Examples of nesting and ConvertTo-Json behavior:
$NestedArray = #(1,#(2,#(3,#(4))))
Default:
$NestedArray | ConvertTo-Json
[
1,
{
"value": [
2,
[
3,
"4"
]
],
"Count": 2
}
]
No nesting at all:
$NestedArray | ConvertTo-Json -Depth 1
[
1,
{
"value": [
2,
"3 System.Object[]"
],
"Count": 2
}
]
Desired result:
$NestedArray | ConvertTo-Json -Depth 3
[
1,
{
"value": [
2,
[
3,
[
4
]
]
],
"Count": 2
}
]