Improvement on Export-Csv that includes milliseconds in DateTime properties

Export-CsvWithMilliseconds.ps1

#requires -version 7.3

# this is one of Stéphane BARIZIEN's public domain scripts
# the most recent version can be found at:
# https://gist.github.com/sba923/bc52cf74197ab3cddce825e8b502e28b#file-export-csvwithmilliseconds-ps1

<#

.SYNOPSIS
Proxy for Export-Csv that adds milliseconds to DateTime properties

.DESCRIPTION
When objects contain properties of type DateTime, Export-Csv doesn't include milliseconds in the resulting CSV file:

[PSCustomObject]@{
    Date = [datetime]"2024-12-31 23:59:59.999"
} | Export-Csv foo.csv
Get-Content foo.csv
"Date"
"2024-12-31 23:59:59"

This proxy script adds milliseconds to the resulting CSV:

[PSCustomObject]@{
    Date = [datetime]"2024-12-31 23:59:59.999"
> } | Export-CsvWithMilliseconds.ps1 foo.csv
> Get-Content foo.csv
"Date"
"2024-12-31 23:59:59.999"

Until https://github.com/PowerShell/PowerShell/issues/19536 is addressed, this is an acceptable workaround.

#>

# original proxy code produced by:
# $MetaData = New-Object System.Management.Automation.CommandMetaData (Get-Command  Export-Csv)
# [System.Management.Automation.ProxyCommand]::Create($MetaData)


[CmdletBinding(DefaultParameterSetName = 'Delimiter', SupportsShouldProcess = $true, ConfirmImpact = 'Medium', HelpUri = 'https://go.microsoft.com/fwlink/?LinkID=2096608')]
param(
    [Parameter(Mandatory = $true, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true)]
    [psobject]
    ${InputObject},

    [Parameter(Position = 0)]
    [ValidateNotNullOrEmpty()]
    [string]
    ${Path},

    [Alias('PSPath', 'LP')]
    [ValidateNotNullOrEmpty()]
    [string]
    ${LiteralPath},

    [switch]
    ${Force},

    [Alias('NoOverwrite')]
    [switch]
    ${NoClobber},

    [ValidateNotNullOrEmpty()]
   # remove typing, see https://github.com/PowerShell/PowerShell/issues/19647
    ${Encoding},

    [switch]
    ${Append},

    [Parameter(ParameterSetName = 'Delimiter', Position = 1)]
    [ValidateNotNull()]
    [char]
    ${Delimiter},

    [Parameter(ParameterSetName = 'UseCulture')]
    [switch]
    ${UseCulture},

    [Alias('ITI')]
    [switch]
    ${IncludeTypeInformation},

    [Alias('NTI')]
    [switch]
    ${NoTypeInformation},

    [Alias('QF')]
    [string[]]
    ${QuoteFields},

    [Alias('UQ')]
    [Microsoft.PowerShell.Commands.BaseCsvWritingCommand+QuoteKind]
    ${UseQuotes})

begin
{
    # derived from https://github.com/PowerShell/PowerShell/issues/19536#issuecomment-1515140128
    # Save the original culture.
    $original = [cultureinfo]::CurrentCulture

    # Temporarily replace it with a read/write copy.
    [cultureinfo]::CurrentCulture = [cultureinfo] $original.Name


    # Modify the LongTimePattern format to include milliseconds.
    [cultureinfo]::CurrentCulture.DateTimeFormat.LongTimePattern += ([cultureinfo]::CurrentCulture.NumberFormat.CurrencyDecimalSeparator + 'fff')

    # Now .ToString(), which uses ShortDatePattern and LongTimePattern, 
    # separated by a space, uses the modified formats.
    
    try
    {
        # removed according to https://github.com/PowerShell/PowerShell/issues/10863
        # $outBuffer = $null
        # if ($PSBoundParameters.TryGetValue('OutBuffer', [ref]$outBuffer))
        # {
        #     $PSBoundParameters['OutBuffer'] = 1
        # }

        $wrappedCmd = $ExecutionContext.InvokeCommand.GetCommand('Microsoft.PowerShell.Utility\Export-Csv', [System.Management.Automation.CommandTypes]::Cmdlet)
        $scriptCmd = { & $wrappedCmd @PSBoundParameters }

        $steppablePipeline = $scriptCmd.GetSteppablePipeline($myInvocation.CommandOrigin)
        $steppablePipeline.Begin($PSCmdlet)
    }
    catch
    {
        # changed according to https://github.com/PowerShell/PowerShell/issues/10863#issuecomment-545533276
        # throw
        $PSCmdlet.ThrowTerminatingError($_)
    }
}

process
{
    try
    {
        $steppablePipeline.Process($_)
    }
    catch
    {
        # changed according to https://github.com/PowerShell/PowerShell/issues/10863#issuecomment-545533276
        # throw
        $PSCmdlet.ThrowTerminatingError($_)
    }
}

end
{

    try
    {
        $steppablePipeline.End()
    }
    catch
    {
        # changed according to https://github.com/PowerShell/PowerShell/issues/10863#issuecomment-545533276
        # throw
        $PSCmdlet.ThrowTerminatingError($_)
    }
}

clean
{
    # Restore culture
    [cultureinfo]::CurrentCulture = $original

    if ($null -ne $steppablePipeline)
    {
        $steppablePipeline.Clean()
    }
}

<#

.ForwardHelpTargetName Microsoft.PowerShell.Utility\Export-Csv
.ForwardHelpCategory Cmdlet

#>

Your workarounds for timestamps with Export-Csv just saved me a ton of time today. Thanks!

Just wanted to let you know that it doesn't work in all cultures to add the milliseconds at the end. In my case, LongTimePattern is h:mm:ss tt (tt is AM/PM, so I would get something like 4/10/1997 10:51:36 PM.000). I ended up using:

[cultureinfo]::CurrentCulture.DateTimeFormat.LongTimePattern = [cultureinfo]::CurrentCulture.DateTimeFormat.LongTimePattern.Replace('ss','ss' + ([cultureinfo]::CurrentCulture.NumberFormat.CurrencyDecimalSeparator + 'FFFFFFF'))

Didn't get a chance to thoroughly test that but it did what I needed for today. (In my case had to go down to 100 ns because I was dealing with file times.)