将字符串转换为Office365的特定格式的System.DateTime

Question

I'm running into an issue with converting user input into a DateTime type while returning it in a specific format. I've been searching for a few hours now and everything I've tried so far hasn't worked.

When I enter the date, I want it to stay as the format I entered it in so that Get-MessageTrace can read it.

What I'm looking for is to enter "1/23/2019" and ParseExact would shoot it back out as "1/23/2019".

What I'm getting is $NewDate1 being "Wednesday, January 23, 2019 12:01:00 AM" I'm probably not doing this right or maybe doing something wrong, but I could use some help, please.

$UserEmail = Read-Host -Prompt 'Enter your WT email address'
$Date1 = Read-Host -Prompt 'Enter the first date (MM/DD/YYYY)'
$Date2 = (Read-Host -Prompt 'Enter the second date (MM/DD/YYYY)'


$NewDate1 = [datetime]::parseexact($Date1, 'm/d/yyyy', $null)
$NewDate2 = [datetime]::parseexact($Date2, 'm/d/yyyy', $null) 


Get-MessageTrace -RecipientAddress 'UserEmail' -StartDate '$NewDate1'
-EndDate 'NewDate2'

Error I receive:

Cannot process argument transformation on parameter 'StartDate'. Cannot convert value "$NewDate1" to type "System.DateTime". Error: "String was not recognized as a valid DateTime." + CategoryInfo : InvalidData: (:) [Get-MessageTrace], ParameterBindin...mationException + FullyQualifiedErrorId : ParameterArgumentTransformationError,Get-MessageTrace + PSComputerName : outlook.office365.com

Answer 1

First, regarding date string formatting, a lower case 'm' represents minutes and an uppercase 'M' represents months. That is why '1/23/2019' is being interpreted as Wednesday, January 23, 2019 12: 01 :00 AM (emphasis on first minute of the day). The pattern you likely want is 'M/d/yyyy'.

Second, I'm not entirely sure you understand date parsing. ParseExact does not take a string and "shoot it back" as a date with a specific string representation. ParseExact will convert a string formatted as a date into a DateTime object. That DateTime object does not have an inherent format or string representation (unless you consider ToString() to be the canonical date format), it's just a date. If, at a later time, you need a string representation of that date you will have to convert it to a string.

Third, you are passing a string with the value of "$NewDate1" to -StartDate , hence the exception stating:

Cannot convert value "$NewDate1" to type "System.DateTime"

Remove the single quotes around '$NewDate1' to pass the value of the variable rather than the name of the variable.