Append Members to an Array in JSON with PowerShell - json

Question

I need to use Powershell to insert data into a json file within an array. Here is the json original structure
{
"Array": [
{
"servername": "foo"
},
{
"servername": "boo"
}
]
}
Here is the new structure:
{
"Array": [
{
"servername": "Foo",
"Disk": "100"
},
{
"servername": "Boo",
"Disk": "500"
}
]
}
Why does this not work?
$json = #"
{
"Array": [
{
"servername": "Foo"
},
{
"servername": "Boo"
}
]
}
"#
$jsonServerFoo=#"
{
"Disk": "100"
}
"#
$jsonServerBoo=#"
{
"Disk": "500"
}
"#
$jsonObj = $JSON | ConvertFrom-Json
$jsonServerFooObj = $jsonServerFoo | ConvertFrom-Json
$jsonServerBooObj = $jsonServerBoo | ConvertFrom-Json
$i = 1
$jsonObj.Array | Foreach-object {
if ( $i -eq 1 ) {
$_ | Add-Member -MemberType NoteProperty -Name "Disk" -Value $jsonServerFooObj.Disk
$i++
}
else {
$_ | Add-Member -MemberType NoteProperty -Name "Disk" -Value $jsonServerBooObj.Disk
}
}
$jsonObj
$jsonObj | ConvertTo-Json -Depth 100
I get the desired output
{
"Array": [
{
"servername": "Foo",
"Disk": "100"
},
{
"servername": "Boo",
"Disk": "500"
}
]
}

Answer 1

Use Add-Member to add members to a PSCustomObject. ConvertFrom-Json returns a PSCustomObject, not a Hashtable.
$jsonObj | Add-Member -MemberType NoteProperty -MemberName MyPropertyName -Value "some value, doesn't have to be a string"
You don't have to work with the base $jsonObj either, you can also add members to nested members of $jsonObj as well. In your case, with the Array member:
$jsonObj.Array | Foreach-object {
if( $i -eq 1 ) {
$_ | Add-Member -MemberType NoteProperty -Name Disk -Value $jsonServerFooObj.Disk
$i++
} else {
$_ | Add-Member -MemberType NoteProperty -Name Disk -Value $jsonServerBooObj.Disk
}
}
You may also want to consider calling ConvertTo-Json -Depth 100 so you don't get the default object depth which is low, 3 I think.
As noted by #user2864740, in PowerShell 6 ConvertFrom-Json has the -AsHashtable parameter if you would rather work with a Hashtable than a PSCustomObject.