Parsing Function return in PowerShell Script - powershell

Question

I am trying to parse the response from one of the functions in PowerShell Script and based on the response I have to make some decision.
The function is returning JSON object successfully but not able to parse the response from the function. I need to check if validnodes count is 0 or not.
[String[]] $NodeList = 'a1572dev00e001','a1572dev00q001'
$Response = Get-Nodes
Write-Output "Response $Response"
$JSRes = $Response | ConvertFrom-Json
Write-Output "Parsing response $JSRes"
#$Result = "success"
if($JSRes.ValidNodes.Count -gt 0)
{
Write-Output "$JSRes.ValidNodes"
$Result = "success"
}
else
{
Write-Output "All nodes are Invalid"
Write-Output "Invalid Nodes: $JSRes.Invalid"
$Result = "failed"
$ErrorMessage = "All nodes are Invalid"
}
Write-Output $Result
#Function
function Get-Nodes
{
$ValidNodes=#()
$InvalidNodes=#()
foreach($Node in $NodeList)
{
if(Get-ADComputer -filter {Name -eq $Node})
{
$ValidNodes +=$Node
}
else
{
$InvalidNodes +=$Node
}
}
$JRes = #{"ValidNodes"=$ValidNodes;"Invalid"=$InvalidNodes} | ConvertTo-Json -Compress
Write-Output $JRes
return $JRes
}
Output:
Response {"ValidNodes":["a1572dev00e001","a1572dev00q001"],"Invalid":[]} {"ValidNodes":["
a1572dev00e001","a1572dev00q001"],"Invalid":[]}
Parsing response
All nodes are Invalid
Invalid Nodes:
failed

Answer 1

One issue is you are outputting the $Jres twice.
Write-Output $JRes
return $JRes
These effectively do the exact same thing. Next, you're using ConvertFrom-String when it seems you should be using ConvertFrom-Json
$JSON = $Response | ConvertFrom-String
Finally, you're trying to output $ValidNodes and $InvalidNodes that only exist in your function. Change these to $JSON.ValidNodes and $JSON.InvalidNodes
One more suggestion is to parameterize the Nodelist so you can just pass the nodes to the function.
#Function
function Get-Nodes
{
Param([string[]]$nodelist)
$ValidNodes=#()
$InvalidNodes=#()
foreach($Node in $NodeList)
{
if(Get-ADComputer -filter {Name -eq $Node})
{
$ValidNodes +=$Node
}
else
{
$InvalidNodes +=$Node
}
}
$JRes = #{"ValidNodes"=$ValidNodes;"Invalid"=$InvalidNodes} | ConvertTo-Json -Compress
$JRes
}
$Response = Get-Nodes a1572dev00e001,a1572dev00q001
Write-Output "Response $Response"
$JSON = $Response | ConvertFrom-Json
Write-Output "Parsing response $JSON"
if($JSON.ValidNodes.Count -gt 0)
{
Write-Output "Valid Nodes: $($JSON.ValidNodes)"
$Result = "success"
}
else
{
Write-Output "All nodes are Invalid"
Write-Output "Invalid Nodes: $($JSON.InValidNodes)"
$Result = "failed"
$ErrorMessage = "All nodes are Invalid"
}
Write-Output $Result