Powershell errorhandling on empty parameters

Question

This is a small script I'm calling from an excel spreadsheet:

Param (
    [Int] $ID,
    [String] $server,
    [String] $db,
    [String] $uid,
    [String] $pw,
    [String] $Navn,
    [String] $Path
)
Try
{
Add-Type -Path $Path

foreach($i in [BrReader2.BrReader]::Main($ID, $uid, $pw, $db, $server)){if($i.Key -eq $Navn){$Data = $i}}

[BrReader2.BrReader]::WriteToTemporaryTable($Data, $ID, $uid, $pw, $db, $server)
}
Catch
{
$ErrorMessage = $_.Exception.Message
Write-Host $ErrorMessage
Read-Host -Prompt "Press Enter to exit"
}

It works mostly pretty well, except for one little thing. If for some reason one of the parameters is entered in the wrong way, like if it's completely empty, it will fail there and not write out an error message. The console window will simply quickly appear and disappear again and the user might not realise what they've done wrong.

Giving a wrong path is fine, it will still enter the try/catch block and write a proper error message to the console. Giving NO path does not keep the console window open so the user can see what went wrong though.

I need to put the 'Param (...' part at the top of the script though, so I can't put it into the try/catch block. Is there any way I can write out an error message and keep the console window open if one of the parameters fail?

I'm not very experienced with powershell so there might be something obvious I'm missing.

[ValidateNotNullOrEmpty()]

Jaqueline Vanek
– Jaqueline Vanek

2018-09-06 10:07:09 +00:00
Commented Sep 6, 2018 at 10:07 — Jaqueline Vanek
– Jaqueline Vanek, Commented Sep 6, 2018 at 10:07

John Seerden · Accepted Answer · 2018-09-06 08:06:10Z

1

If you want the parameters to be set, you can make them mandatory.

If they should contain a certain value, you can also validate them.

For example:

Param (
    [Parameter(Mandatory = $true)]
    [ValidateRange(10,99)] 
    [Int] $ID,

    [Parameter(Mandatory = $true)]
    [String] $server,

    [Parameter(Mandatory = $true)]
    [ValidateSet("sql01.contoso.local","sql02.contoso.local")] 
    [String] $db,

    [Parameter(Mandatory = $true)]
    [String] $uid,

    [Parameter(Mandatory = $true)]
    [String] $pw,

    [Parameter(Mandatory = $true)]
    [String] $Navn,

    [Parameter(Mandatory = $true)]
    [ValidateScript({Test-Path $_ -PathType 'Container'})] 
    [String] $Path
)

answered Sep 6, 2018 at 8:06

John Seerden

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