Powershell script - manage empty parameters

Question

Am automating youtubeDl tasks with Powershell via some functions in profile.ps1 This function accepts different parameters - if some are set, i'll setup additional config to youtube-dl executable.

For instance, executing ytDl https://vimeo.com/1548390390 would result in executing .\youtube-dl.exe https://vimeo.com/1548390390. When executing ytDl https://vimeo.com/1548390390 3458F89 would lead to .\youtube-dl.exe https://vimeo.com/1548390390 --video-password 3458F89

Am able to do what i want working script is not "beautiful"/"clean". I pasted below the two versions.

Can anyone of you help me - explain me why it's not behaving as expected ? Thanks a lot !

function ytDl_Working_But_NotBeautiful {
    param (
        [Parameter(Mandatory = $true, Position = 0)][string]$url,
        [Parameter(Mandatory = $false, Position = 1)][string]$password,
        [Parameter(Mandatory = $false, Position = 2)][string]$youtubeDlPath = "C:\APPS\"
    )
        Write-Host "URL = $url || Password = $password"
        
        cd $youtubeDlPath
        
        if ($password.Length -gt 0) {
            Write-Host "Password set - adding video-password parameter"
            .\youtube-dl.exe $url --video-password $password
        }
        else{
            .\youtube-dl.exe $url
        }
}

function ytDl_NotWorking {
    param (
        [Parameter(Mandatory = $true, Position = 0)][string]$url,
        [Parameter(Mandatory = $false, Position = 1)][string]$password,
        [Parameter(Mandatory = $false, Position = 2)][string]$youtubeDlPath = "C:\APPS\"
    )
        Write-Host "URL = $url || Password = $password"
        
        $fullParams = $url
        if ($password.Length -gt 0) {
            Write-Host "Password set - adding video-password parameter"
            $fullParams = "$url --video-password $password"
        }
        Write-Host ".\youtube-dl.exe $fullParams"
        
        .\youtube-dl.exe $fullParams
}

You forgot to tell us what exactly you are expecting and how these functions defy your expectations. — Mathias R. Jessen
– Mathias R. Jessen, Commented Nov 5, 2020 at 20:14
When i launch ytDl with some parameters, it works (sets properly the extra parameter) ytDl https://vimeo.com/473689210 2345no [vimeo] 473689210: Downloading webpage [vimeo] 473689210: Extracting information [vimeo] 473689210: Verifying the password When launching ytDl2 with same param; it fails ytDl2 https://vimeo.com/473689210 2345no Password set - adding video-password parameter [vimeo:user] 473689210 --video-password 2345no: Downloading page 1 Which means parameters are not properly set. Thus this question :) — Franck Deny
– Franck Deny, Commented Nov 5, 2020 at 20:44

Mathias R. Jessen · Accepted Answer · 2020-11-05 21:05:04Z

2

If you want to pass a variable number of arguments to an executable without having to write many nested if/else statements, take advantage of splatting!

function Save-OnlineVideo
{
    param (
        [Parameter(Mandatory = $true, Position = 0)][string]$url,
        [Parameter(Mandatory = $false, Position = 1)][string]$password,
        [Parameter(Mandatory = $false, Position = 2)][string]$youtubeDlPath = "C:\APPS\"
    )

    # Create array to hold the arguments
    $fullParams = @($url)

    if ($password.Length -gt 0) {
        # Add any additional arguments to the array
        $fullParams += "--video-password","$password"
    }

    # prepend variable name with @ instead of $ to make powershell splat them
    .\youtube-dl.exe @fullParams
}

edited Nov 5, 2020 at 21:05

answered Nov 5, 2020 at 20:44

Mathias R. Jessen

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3 Comments

Franck Deny Over a year ago

Unfortunately, it is not working. Usage: youtube-dl.exe [OPTIONS] URL [URL...] youtube-dl.exe: error: no such option: --video-password PASSWORD My understanding is that we are setting one parameter ( --video-password PASSWORD) whilst we should be setting a -- --video-password parameter which value is PASSWORD.

Mathias R. Jessen Over a year ago

@FranckDeny Updated the answer

Franck Deny Over a year ago

BTW - thanks to your splatting explanation, i now understand many scripts i've seen before :)

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