Migrating Document libraries to new location (and new subsite) while retaining internal ID's

Question

I'm currently using SPExportSettings and SPImportSettings to migrate some content from an old 2007 environment.

The below code is all working fine, as designed, but not as I'd like. My document libraries need to retain their internal ID's after the migration.

Because I have RetainObjectIdentity = $true on the import, that seems to keep the libraries URL structure in tact, so it ignores my $_destWebUrl, for where to import to (they originate in the rootweb so they are being deployed to the new rootweb).

If I set RetainObjectIdentity = $false, then it's imported to the subsite as I'd like, but the ID's are all gone.

Desired Source: http://sharepoint/MigrationSource

Desired Target: http://sharepoint/MigrationTarget/SUBSITE

Relevant export code:

$settings = New-Object Microsoft.SharePoint.Deployment.SPExportSettings
$settings.SiteUrl = $_sourceSite
$settings.ExportMethod = [Microsoft.SharePoint.Deployment.SPExportMethodType]::ExportAll
$settings.IncludeSecurity = [Microsoft.SharePoint.Deployment.SPIncludeSecurity]::All
$settings.FileLocation = $_fileLocation
$settings.FileCompression = $true
$settings.BaseFileName = $_fileName
$settings.OverwriteExistingDataFile = $true
$settings.IncludeVersions = [Microsoft.SharePoint.Deployment.SPIncludeVersions]::All

....snip

foreach ($obj in $_exportObjs)
{
    # Create a new SPExportObject which contains the content to be exported
    $exportObject = New-Object Microsoft.SharePoint.Deployment.SPExportObject
    $exportObject.IncludeDescendants = [Microsoft.SharePoint.Deployment.SPIncludeDescendants]::All
    $exportObject.Type = [Microsoft.SharePoint.Deployment.SPDeploymentObjectType]::List
    $exportObject.Id = $_spweb.Lists.TryGetList($obj).ID
    $settings.ExportObjects.Add($exportObject)
    Write-Host `t`t$obj" has been added"
}

And import code:

$settings = New-Object Microsoft.SharePoint.Deployment.SPImportSettings
$settings.SiteUrl = $_destSiteUrl
$settings.WebUrl = $_destWebUrl
$settings.FileLocation = $_fileLocation
$settings.BaseFileName = $_fileName
$settings.FileCompression = $true
$settings.RetainObjectIdentity = $true
$settings.UserInfoDateTime = [Microsoft.SharePoint.Deployment.SPImportUserInfoDateTimeOption]::ImportAll

If there is no way around this issue, is there a way to move a document library, within a site collection, while retaining all internal ID's?

Answer 1

Answering my own question here after I've had some time to look at it. This is expected functionality. If a List/Library exists in the Root web, in order to keep its identity, it can only be imported into the root web of the target site.

Of course, if you choose NOT to retain identities, you can subscribe to the SPImport's events and set their parents.