'How to check if a DateTime value is not null or empty?

I want to check if the DateTime field is not an empty\null string. if datetime field is not null then I will do stuff.

[DateTime]$expdate = Read-Host "Expiration Date? MM/DD/YYYY"
$newexpdate = $expdate.AddDays(1)
if (!([DateTime]$expdate -eq "")) {
    Write-Host -ForegroundColor Green $($newexpdate) "Date Time entered"
}

Here is my error message:

Cannot convert value "" to type "System.DateTime". Error: "String was not
recognized as a valid DateTime."
At line:1 char:2
+     [DateTime]$expdate = Read-Host "Expiration Date? MM/DD/YYYY"
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : MetadataError: (:) [], ArgumentTransformationMetadataException
    + FullyQualifiedErrorId : RuntimeException`

What can I do to check if a field is not a string but is DateTime object?

powershelldatetime


Solution 1:[1]

Why prompt for user input when you can declare a mandatory DateTime-type parameter to a function or script? If the parameter is missing, PowerShell will prompt the user for the date and time and the user can enter it at runtime. (If you use Read-Host, you can't automate.)

Solution 2:[2]

There is no empty [DateTime] value, it can either be a $null or a datetime value.

Read-Host returns string type. What you're trying to do is assigning string values to a [DateTime] type which will cause error.

You can rewrite your code like this:

$expdate = Read-Host "Expiration Date? MM/DD/YYYY"
if (![string]::IsNullOrEmpty($expdate))) {
   #add logic to check $expdate is valid datetime
   #then you can do this
   $newexpdate = ([DateTime]$expdate).AddDays(1)
   Write-Host -ForegroundColor Green $($newexpdate) "Date Time entered"
}

Solution 3:[3]

Your logic doesn't make much sense, but here's what I think you're trying to do (below). To directly address your last question, you can test the type of an object by using the -is or -isNot operator which will return $True\ $False depending on the match. The other side of the operator can be a string or type accelerator, i.e. [DateTime]'10/10/2010' -is 'DateTime' or [DateTime]'10/10/2010' -is [DateTime] both evaluate to $True

Do
{
    $ExpDate = Read-Host -Prompt 'Expiration date? MM/DD/YYYY'
} Until ($ExpDate -match '\d{1,2}\/\d{1,2}\/\d{2,4}')

$NewExpDate = ([DateTime]$ExpDate).AddDays(1)

If ($ExpDate)
{
    Write-Host "$NewExpDate Date Time entered." -ForegroundColor 'Green'
}

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Bill_Stewart
Solution 2 I'm A Guest
Solution 3

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