Powershell hashtable in function not accessible - function

Question

I created a function to import HR records so they're easily accessible by indexing the employeeID.
function hrDataImport {
$HRFile=Import-Csv $rawHRFile #$rawHRFile path previously defined
Write-Host "Creating HR hash table..."
$hrData = #{}
$HRFile | ForEach-Object { $hrData[$_.employeeID] = $_ }
Write-Host "Done. " $hrData.Count
}
I'd like to use that $hrData variable outside the function. I can't reference $hrData['employeeID'] as I've read that variables in functions don't exist outside the function. One thing I tried is creating another function to pass an employeeID into the $hrData hashtable:
function showHRData {
param ([string]$hrUser)
$hrData[$hrUser]
}
I put the functions in a module and imported successfully. I'm able to execute importHRData fine but when I try showHRData -hrUser $employeeID I get "Cannot index into a null array". Seems like the function does not see the hashtable variable from the previous function. What am I doing wrong or what would you suggest so I can access that $hrData hashtable across various scripts?

Answer 1

You might create a Hashtable within your function using a $global (or $script) scope like this:
function hrDataImport {
$HRFile = Import-Csv $rawHRFile #$rawHRFile path previously defined
Write-Host "Creating HR hash table..."
if (!$hrData) { $Global:hrData = #{} }
$HRFile | ForEach-Object { $Global:hrData[$_.employeeID] = $_ }
Write-Host "Done. " $hrData.Count
}
But in general it is advised to avoid the global (or script) scope mainly because it might conflict with variables in the current scope.
To minimize this possibility, I would consider to change the responsibility of your function to not only loading the information but also to receiving the concerned employeeID, e.g.:
function Get-EmployeeData ($EmployeeID) {
if (!$StaticEmployeeData) {
Write-Host "Creating HR hash table..."
$HRFile = Import-Csv $rawHRFile #$rawHRFile path previously defined
$Global:StaticEmployeeData = #{}
$HRFile | ForEach-Object { $Global:StaticEmployeeData[$_.employeeID] = $_ }
Write-Host "Done. " $StaticEmployeeData.Count
}
$Global:StaticEmployeeData[$employeeID]
}
function showHRData {
param ([string]$hrUser)
Get-EmployeeData $hrUser
}
In that case you might choose for a more specific global variable name (e.g. $StaticEmployeeData, knowing that PowerShell doesn't support something like a static variable) and as an extra bonus the data is only loaded the first time you really need it (lazy evaluation).