Sql server Powershell SMO SQL Server还原出现问题

我在执行Powershell SQL还原时遇到问题。我有这个密码

[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.SMO") | Out-Null
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.SmoExtended") | Out-Null
[Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.ConnectionInfo") | Out-Null
[Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.SmoEnum") | Out-Null

$backupFile = 'C:\Temp\User_20191029152532.bak'

$server = New-Object ("Microsoft.SqlServer.Management.Smo.Server") "(local)"
$backupDevice = New-Object("Microsoft.SqlServer.Management.Smo.BackupDeviceItem") ($backupFile, "File")
$smoRestore = new-object("Microsoft.SqlServer.Management.Smo.Restore")

$smoRestore.NoRecovery = $false;
$smoRestore.ReplaceDatabase = $true;
$smoRestore.Action = "Database"
$smoRestorePercentCompleteNotification = 10;
$smoRestore.Devices.Add($backupDevice)

$smoRestoreDetails = $smoRestore.ReadBackupHeader($server)

"Database Name from Backup Header : " +$smoRestoreDetails.Rows[0]["DatabaseName"]

$smoRestore.Database =$smoRestoreDetails.Rows[0]["DatabaseName"]

$smoRestoreFile = New-Object("Microsoft.SqlServer.Management.Smo.RelocateFile")
$smoRestoreLog = New-Object("Microsoft.SqlServer.Management.Smo.RelocateFile")

$smoRestoreFile.LogicalFileName = $smoRestoreDetails.Rows[0]["DatabaseName"]
$smoRestoreFile.PhysicalFileName = $server.Information.MasterDBPath + "\" + $smoRestore.Database + "_Data.mdf"
$smoRestoreLog.LogicalFileName = $smoRestoreDetails.Rows[0]["DatabaseName"] + "_Log"
$smoRestoreLog.PhysicalFileName = $server.Information.MasterDBLogPath + "\" + $smoRestore.Database + "_Log.ldf"
$smoRestore.RelocateFiles.Add($smoRestoreFile)
$smoRestore.RelocateFiles.Add($smoRestoreLog)

$smoRestore.SqlRestore($server)

如果我运行这个，一切正常。但是，我想提供一个变量，用于恢复备份。因此，我将代码的顶部更改为：

$path = 'C:\Temp'
$db_name = 'User'
$file = Get-ChildItem $path '*.bak' | Select-Object basename | Where-Object {$_.basename -like $db_name + '*' }

$backupFile = $path + '\' + $file

当我进行此更改时，我开始出现以下错误

使用“1”参数调用“ReadBackupReader”时发生异常：“执行Transact-SQL语句或批处理时发生异常。”

第23行字符：1
+$smoRestoreDetails=$smoRestore.ReadBackupReader（$server）
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+CategoryInfo:NotSpecified:（：）[]，MethodInvocationException
+FullyQualifiedErrorId:ExecutionFailureException

---

我不确定它为什么不接受我传递的$file变量。如果我查看变量，它返回的值是正确的。

这是我的愚蠢问题$文件未包含扩展名。将.bak添加到$file修复了该问题