Powershell-清除active directory属性后无法检索该属性

我正在清除计算机的广告属性。 然后我尝试将该属性更改为某个值。但是，当我查看该AD对象的属性时，该属性似乎不再存在：

function clearAttribute
{
    $directorySearcher = New-Object System.DirectoryServices.DirectorySearcher
    $directorySearcher.PageSize = 100
    $directorySearcher.SearchScope = [System.DirectoryServices.SearchScope]::Subtree
    $directorySearcher.Filter = "(&(objectCategory=computer)(cn=computerName1))"
    $result = $directorySearcher.FindOne()
    if ($result.Properties.Contains("netbootmachinefilepath"))
    {
        $directoryEntry = $result.GetDirectoryEntry()
        $directoryEntry.Properties["netbootmachinefilepath"].Clear()
        $directoryEntry.CommitChanges()
    }
}

function setAttribute
{
    $directorySearcher = New-Object System.DirectoryServices.DirectorySearcher
    $directorySearcher.PageSize = 100
    $directorySearcher.SearchScope = [System.DirectoryServices.SearchScope]::Subtree
    $directorySearcher.Filter = "(&(objectCategory=computer)(cn=computerName1))"
    $result = $directorySearcher.FindOne()
    if ($result.Properties.Contains("netbootmachinefilepath")) ###THIS IS FALSE!###
    {
        $directoryEntry = $result.GetDirectoryEntry()
        $directoryEntry.Properties["netbootmachinefilepath"].Value = "someValue"
        $directoryEntry.CommitChanges()
    }
}
clearAttribute
setAttribute

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编辑：结果显示此属性可以是非空的，也可以是删除的（不能是空的）。“清除”它之后，如果要更新该值，则必须重新创建它。

结果是，我错误地认为如果$result.Properties.Contains（“netbootmachinefilepath”）=FALSE，则无法设置该属性的值。 事实并非如此。 $result.Properties.Contains（“netbootmachinefilepath”）=FALSE表示该值为null（或者该属性不存在？）

如果您仅删除如下所示的If语句，代码将正常工作：

function setAttribute
{
    $directorySearcher = New-Object System.DirectoryServices.DirectorySearcher
    $directorySearcher.PageSize = 100
    $directorySearcher.SearchScope = [System.DirectoryServices.SearchScope]::Subtree
    $directorySearcher.Filter = "(&(objectCategory=computer)(cn=computerName1))"
    $result = $directorySearcher.FindOne()

    $directoryEntry = $result.GetDirectoryEntry()
    $directoryEntry.Properties["netbootmachinefilepath"].Value = "someValue"
    $directoryEntry.CommitChanges()
}