How to create an open file/folder dialog box with PowerShell

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Adam Bertram

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When you're using a Windows application and need to provide input for a file or folder, you've probably seen the standard open file dialog.

Open file dialog

This dialog box is standard across lots of Windows applications. The software you're using to invoke this dialog box uses a .NET assembly called System.Windows.Forms with a class inside called OpenFileDialog. Did you know you can get input to your PowerShell scripts this way too? Since PowerShell lies directly on top of .NET, we can invoke any .NET class we need, which means we can also bring up the open file dialog box.

To do this, we'll first need to load the System.Windows.Forms assembly manually using the Add-Type cmdlet. Lots of .NET assemblies are typically loaded for you, but in this case, we have to do it manually.

Add-Type -AssemblyName System.Windows.Forms

Once we've loaded the assembly, we can instantiate an OpenFileDialog object using New-Object.

$FileBrowser = New-Object System.Windows.Forms.OpenFileDialog -Property @{ InitialDirectory = [Environment]::GetFolderPath('Desktop') }

You can see above that the OpenFileDialog class constructor has an InitialDirectory argument. This tells the OpenFileDialog class which folder to display when the dialog box comes up. In this case, I have the dialog box to display the desktop.

At this point, the dialog box will not display. We're just instantiating the object. To show the dialog box, we'll have to use the ShowDialog() method.

$null = $FileBrowser.ShowDialog()

This will display the dialog box. I'm assigning the output of ShowDialog() to $null. This is because the output does not return anything useful for our purposes. You might expect the output to return the chosen file name, but it doesn't. The system then stores the file information in the OpenFileDialog object itself.

PS C:\> $FileBrowser

CheckFileExists              : True
Multiselect                  : False
ReadOnlyChecked              : False
ShowReadOnly                 : False
SafeFileName                 : Thumbs.db
SafeFileNames                : {Thumbs.db}
AddExtension                 : True
CheckPathExists              : True
DefaultExt                   :
DereferenceLinks             : True
FileName                     : \\Mac\Home\Desktop\Thumbs.db
FileNames                    : {\\Mac\Home\Desktop\Thumbs.db}
Filter                       :
FilterIndex                  : 0
InitialDirectory             : \\Mac\Home\Desktop
RestoreDirectory             : False
ShowHelp                     : False
SupportMultiDottedExtensions : False
Title                        :
ValidateNames                : True
CustomPlaces                 : {}
AutoUpgradeEnabled           : True
Tag                          :
Site                         :
Container                    :

You can see above that the OpenFileDialog object now contains all the information gathered from the file chosen.

The above example allows me to choose any file we'd like, but we also can limit the input by file type too using the Filter property.

$FileBrowser = New-Object System.Windows.Forms.OpenFileDialog -Property @{ 
    InitialDirectory = [Environment]::GetFolderPath('Desktop') 
    Filter = 'Documents (*.docx)|*.docx|SpreadSheet (*.xlsx)|*.xlsx'
}
$null = $FileBrowser.ShowDialog()

Now when the dialog box displays, you can see below that the only options are to choose between Word and Excel documents.

Filtering by file

For more information about this method of receiving file location input from users, refer to the Microsoft MSDN information.