Remove attribute and reformat date string in a file - powershell

Question

I'm able to remove the attribute using the codes below. However, I don't know how to reformat a date string to the ISO format. From date="20140424T140222Z" to date="2014-04-24T14:02:22Z"
function update {
$unzippedLocation = Get-ChildItem $destination -Recurse
# from date="20140424T140222Z" to date="2014-04-24T14:02:22Z"
Message "Remove and reformat attributes"
$regex='date="(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})(\d{2})Z"'
ForEach($unzippedFile in $unzippedLocation) {
(Get-Content $unzippedFile) |
ForEach-Object { $_ -replace ' crc=""', '' } |
ForEach-Object { $_ -replace $regex, 'date="$1-$2-$3T$4:$5:$6Z"' } |
Set-Content $unzippedFile
Write-Host "crc attribute has been removed from $($unzippedFile.Name)"
Write-Host "date attribute has been reformated from $($unzippedFile.Name)"
}
}

Answer 1

I don't fully understand where you need to that the replacement of the date, but one approach is to use regular expression to update the date. Here is a sample for one string, you can incorporate it where you need to:
#Defines regex with a separate group for each component
$regex='date="(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})(\d{2})Z"'
#Sample input
$input = 'date="20140424T140222Z"'
#Update the string
$result = $input -replace $regex, 'date="$1-$2-$3T$4:$5:$6Z"'
Write-Host $result
#Result is
#date="2014-04-24T14:02:22Z"

Answer 2

You can use the .net method TryParseExact.
This method will try to parse any string in a valid DateTime value and then you format back to ISO format. Using this method you test if your values are valid.
Example:
$dateString = "20140424T140222Z"
$format = "yyyyMMddTHHmmssZ"
[ref]$parsedDate = get-date
$parsed = [DateTime]::TryParseExact($dateString, $format,[System.Globalization.CultureInfo]::InvariantCulture,[System.Globalization.DateTimeStyles]::None,$parseddate)
if($parsed)
{
write "$dateString is valid"
}
$parseddate.Value.ToString("yyyy-MM-ddTHH:mm:ssZ")