In FIM 2010 we couldn’t update DateTime attribute types using the Configuration Migration PowerShell cmdlets.  This used to crop up from time to time and has hampered quite a few people over the last couple of years.  The good news is that this problem has been fixed in FIM 2010 R2.  In FIM 2010 R2 you can happily modify DateTime attribute values using PowerShell as long as you submit the DateTime value, as a String, in the correct format: ISO-8601 with three digits of fractional precision, i.e. yyyy-MM-ddTHH:mm::ss.fff.

ISO-8601 with three digits of fractional precision

The date/time format expected by the FIM Service web service is the ISO-8601 with three digits of fractional precision format: yyyy-MM-ddTHH:mm::ss.fff.  For example, to flow 01/06/2012 as the start date you would flow: 2012-06-01T00:00:00.000.

Example PowerShell code

The following example updates the EmployeeEndDate of the user PAULW.

# It is assumed that you are executing this script locally on a server that hosts the FIM Service.
# For the purpose of this example, we're targeting a user Paul Williams with an AccountName value
# of PAULW.
[String]$targetAccountName = "paulw";

# Load FIMAutomation module if not already loaded
if(@(Get-PSSnapin | ? { $_.Name -eq "FIMAutomation" } ).Count -eq 0)
{
    Add-PSSnapin FIMAutomation;
}

# Get the target resource's GUID
[String]$targetGuid = (
    Export-FIMConfig `
        -OnlyBaseResources `
        -CustomConfig "/Person[AccountName = '$targetAccountName']"
    ).ResourceManagementObject.ObjectIdentifier;

# Create the import object for the target resource
[Microsoft.ResourceManagement.Automation.ObjectModel.ImportObject]$importObject = `
    New-Object Microsoft.ResourceManagement.Automation.ObjectModel.ImportObject;
$importObject.ObjectType = "Person";
$importObject.TargetObjectIdentifier = $targetGuid;
$importObject.SourceObjectIdentifier = $targetGuid;
$importObject.State = [Microsoft.ResourceManagement.Automation.ObjectModel.ImportState]::Put;

# Create the change
[Microsoft.ResourceManagement.Automation.ObjectModel.ImportChange]$importChange = `
    New-Object Microsoft.ResourceManagement.Automation.ObjectModel.ImportChange;
$importChange.Operation = [Microsoft.ResourceManagement.Automation.ObjectModel.ImportOperation]::Replace;
$importChange.AttributeName = "EmployeeEndDate";
$importChange.AttributeValue = "2012-06-01T00:00:00.000";
$importChange.FullyResolved = $true;
$importChange.Locale = "Invariant";

# Add the change to the import object
$importObject.Changes += $importChange;

# Submit to FIM Service WS endpoint
Import-FIMConfig -ImportObject $importObject;

Value does not conform to a valid date time format

Note that if the DateTime value is incorrect you’ll get the following error:

Import-FIMConfig : Failure when making web service call.

SourceObjectID = urn:uuid:982e33ee-f107-4382-b411-fd09d6156eeb
Error = System.InvalidCastException: Attribute EmployeeEndDate with value 01/06/2012T00:59:00 does not conform to a valid date time format.
at Microsoft.ResourceManagement.Automation.ImportConfig.UnifiedClientPut(List`1 changeList, UniqueIdentifier objectIdentifier, String objectType, CultureInfo locale)
at Microsoft.ResourceManagement.Automation.ImportConfig.ProcessLocaleBucket(String objectIdentifier, String objectType, Dictionary`2 localeBucket)
at Microsoft.ResourceManagement.Automation.ImportConfig.Put(String objectIdentifier, String objectType, List`1 changeList)
at Microsoft.ResourceManagement.Automation.ImportConfig.EndProcessing()
At line:41 char:17
+ Import-FIMConfig <<<<  -ImportObject $importObject;
+ CategoryInfo          : InvalidOperation: (:) [Import-FIMConfig], InvalidOperationException
+ FullyQualifiedErrorId : ImportConfig,Microsoft.ResourceManagement.Automation.ImportConfig

Note the clear error:

Error = System.InvalidCastException: Attribute EmployeeEndDate with value 01/06/2012T00:59:00 does not conform to a valid date time format.

Other valid DateTime formats

At the start of this post I made a point of clearly stating that you need to use the ISO-8601 with three digits of fractional precision format.  This is not strictly true.  I said this because there are other scenarios whereby you have to use this format, e.g. when exporting DateTime values via the FIM MA.  Within the confines of the PowerShell example you can use other valid string representations of DateTime objects, e.g.

• 2012-06-01 00:00:00
• 01 June 2012 00:00:00

From limited testing it looks like we can use any valid string representation supported by System.DateTime.  I guess this means any of the valid patterns supported by System.Globalization.DateTimeFormatInfo.