The System.Windows.Forms.OpenFileDialog component opens the Windows dialog box for browsing and selecting files. To open and read the selected files, you can use the OpenFileDialog.OpenFile method, or create an instance of the System.IO.StreamReader class. The following examples show both approaches. The following code example uses the OpenFileDialog implementation of FileDialog and illustrates creating, setting of properties, and showing the dialog box. The example uses the RestoreDirectory property to ensure that the previously selected directory is restored when the dialog box is closed. OpenFileDialog can be used to safely retrieve file names by applications running with partial trust (see Security (WPF)). Using Microsoft.Win32 removes the ability to use DialogResult and instead Nullable is used. For this question, it looks like it is the usage of System.Windows.Forms.OpenFileDialog, we can do like this. The System.Windows.Forms.OpenFileDialog component opens the Windows dialog box for browsing and selecting files. To open and read the selected files, you can use the OpenFileDialog.OpenFile method, or create an instance of the System.IO.StreamReader class. The following examples show both approaches.
- How To: Read Text From A File
- OpenFileDialog.OpenFile Method (System.Windows.Forms ...
- System.windows.forms.openfiledialog Select Folder
How To: Read Text From A File
Note: This tip requires PowerShell 2.0 or above.
In PowerShell, it is possible to use GUI elements to request user input. Although it is possible to create your own forms from scratch, there are also many useful pre-built dialogs available. In this tip, I will show you how to use the System.Windows.Forms.OpenFileDialog to select one or multiple files.
The following code will open a window that will prompt the user to select a single file. By setting the InitialDirectory property, the starting directory will be set to the current user’s desktop. This is done by using the [Environment] Desktop special folder:
If documents need to be selected, it can be useful to set the starting folder to the documents folder. By setting a filter, we can ensure that only a certain type of file is selected. The next code sample will allow users to select .docx files. The filter can be changed by the user to also select an xlsx file:
To select multiple files the MultiSelect property should be set to True.
For more information about this class the following MSDN article can be used:
RadOpenFileDialog is a modal dialog box that allows you to specify one or multiple file names to open.
Figure 1: RadOpenFileDialog in single selection mode
Showing the Dialog
To show the dialog call its ShowDialog method. If a valid file is opened when you press OK, the DialogResult property will return OK and the FileName, and FileNames properties will be set. You can use FileName and FileNames to get the names of the selected items.
Note that when the ShowDialog method is called the UI of the host application will freeze until the dialog closes.
Example 1: Show an open file dialog
Opening the Selected File
You can open a read-only file stream for the selected file using the OpenFile method. Or alternatively you can use the FileName and FileNames properties and open the file manually.
Example 2: Open a file stream
Enabling Multiple Selection
OpenFileDialog.OpenFile Method (System.Windows.Forms ...
The dialog supports single and multiple selection modes. By default, you can select only one file at a time. To alter this you can set the Multiselect property of RadOpenFileDialog to True.
Example 3: Enable multiple selection
Figure 2: Multiple selection
Working with the Selected Files
You can get the paths of the selected files via the FileName and FileNames properties. Note that the properties are empty until the DialogResult is valid. When you open file(s) the properties will return the corresponding paths.
You can get only the name of the selected files, without the full path, via the SafeFileNames collection property.
Example 4: Get the selected file names
The FileName property can be set manually. This will change the value displayed in the selected file auto-complete box area. Note that setting this won't change the selected item in the list with the files.
System.windows.forms.openfiledialog Select Folder
Saving the Last Used Directory
You can save the last used directory by setting the RestoreDirectory property of the RadOpenFileDialog. After setting this property to True and opening a file the InitialDirectory of this RadOpenFileDialog instance will be set to the parent folder of the opened file.
Example 5: Set RestoreDirectory property
Enabling ReadOnly CheckBox
You can display a checkbox to control whether the file should be opened in readonly mode with the ShowReadOnly property of the RadOpenFileDialog. You can control the state of that checkbox by using the ReadOnlyChecked property of the RadOpenFileDialog.
Example 6: Enabling the ReadOnly CheckBox
Figure 3: RadOpenFileDialog with Checked ReadOnly CheckBox
DereferenceLinks
RadOpenFileDialog exposes a DereferenceLinks property indicating whether a file dialog returns the location of the file referenced by a shortcut or the location of the actual shortcut file (with the .lnk extension).
Example 7: Using the DereferenceLinks property
If in multiple or single selection the first selected item is a link to a directory and DereferenceLinks is set to True, clicking the Open button will actually navigate to this directory.