How to loop through arrays in hash table - passing parameters based on values read from a CSV file - powershell

Question

Curious about how to loop through a hash table where each value is an array. Example:
$test = #{
a = "a","1";
b = "b","2";
c = "c","3";
}
Then I would like to do something like:
foreach ($T in $test) {
write-output $T
}
Expected result would be something like:
name value
a a
b b
c c
a 1
b 2
c 3
That's not what currently happens and my use case is to basically pass a hash of parameters to a function in a loop. My approach might be all wrong, but figured I would ask and see if anyone's tried to do this?
Edit**
A bit more clarification. What I'm basically trying to do is pass a lot of array values into a function and loop through those in the hash table prior to passing to a nested function. Example:
First something like:
$parameters = import-csv .\NewComputers.csv
Then something like
$parameters | New-LabVM
Lab VM Code below:
function New-LabVM
{
[CmdletBinding()]
Param (
# Param1 help description
[Parameter(Mandatory=$true,
Position=0,
ValueFromPipeline=$true,
ValueFromPipelineByPropertyName=$true)]
[Alias("p1")]
[string[]]$ServerName,
# Param2 help description
[Parameter(Position = 1)]
[int[]]$RAM = 2GB,
# Param3 help description
[Parameter(Position=2)]
[int[]]$ServerHardDriveSize = 40gb,
# Parameter help description
[Parameter(Position=3)]
[int[]]$VMRootPath = "D:\VirtualMachines",
[Parameter(Position=4)]
[int[]]$NetworkSwitch = "VM Switch 1",
[Parameter(Position=4)]
[int[]]$ISO = "D:\ISO\Win2k12.ISO"
)
process
{
New-Item -Path $VMRootPath\$ServerName -ItemType Directory
$Arguments = #{
Name = $ServerName;
MemoryStartupBytes = $RAM;
NewVHDPath = "$VMRootPath\$ServerName\$ServerName.vhdx";
NewVHDSizeBytes = $ServerHardDriveSize
SwitchName = $NetworkSwitch;}
foreach ($Argument in $Arguments){
# Create Virtual Machines
New-VM #Arguments
# Configure Virtual Machines
Set-VMDvdDrive -VMName $ServerName -Path $ISO
Start-VM $ServerName
}
# Create Virtual Machines
New-VM #Arguments
}
}

Answer 1

What you're looking for is parameter splatting.
The most robust way to do that is via hashtables, so you must convert the custom-object instances output by Import-Csv to hashtables:
Import-Csv .\NewComputers.csv | ForEach-Object {
# Convert the custom object at hand to a hashtable.
$htParams = #{}
$_.psobject.properties | ForEach-Object { $htParams[$_.Name] = $_.Value }
# Pass the hashtable via splatting (#) to the target function.
New-LabVM #htParams
}
Note that since parameter binding via splatting is key-based (the hashtable keys are matched against the parameter names), it is fine to use a regular hashtable with its unpredictable key ordering (no need for an ordered hashtable ([ordered] #{ ... }) in this case).

Answer 2

Try this:
for($i=0;$i -lt $test.Count; $i++)
{$test.keys | %{write-host $test.$_[$i]}}
Weirdly, it outputs everything in the wrong order (because $test.keys outputs it backwards).
EDIT: Here's your solution.
Using the [System.Collections.Specialized.OrderedDictionary] type, you guarantee that the output will come out the same order as you entered it.
$test = [ordered] #{
a = "a","1";
b = "b","2";
c = "c","3";
}
After running the same solution code as before, you get exactly the output you wanted.