How to manually parse listing lines

Xceed FTP for .NET currently provides automatic support for listing the contents of AS400, DOS (Windows), UNIX and VMS FTP servers when calling the GetItems, GetFiles, or GetFolders methods. To modify or manually parse the listing lines returned by the FTP server, the ParsingListingLine event can be used, or a new listing parser added to the FTP connection's ListingParsers collection.

Usually, if you only want to modify or filter the listing lines returned by the GetItems, GetFiles or GetFolders methods, you would handle the ParsingListingLine event rather than creating a listing parser. If however, you want to support the listing lines returned by an FTP server that is not automatically supported by Xceed FTP for .NET, then your best option would be to create a listing parser as it will make it easier to reuse your code.

To create a custom listing parser, create a class that derives from the FtpListingParser class and override the ParseLine method. In the ParseLine method, parse the line that is received as a parameter to create and return a new FtpItemInfo object that contains the FTP item's information. Once you have your custom listing parser, add it to the FTP connection's ListingParsers collection.

The following example demonstrates how use the ParsingListingLine event to manually parse the listing lines returned by an FTP server to remove the potential "." and ".." items:

Create an instance of the FtpConnection class to establish a connection between the client and the FTP server. If you are using FtpConnection in a UI application, assign your form (or any other control that implements the ISynchronizeInvoke interface) to the SynchronizingObject property and call Application.DoEvents in an event.
Subscribe to the FtpConnection's ParsingListingLine event. In your ParsingListingLine event handler, remove any instances of "." and ".." by setting the Valid parameter to false if one of them are encountered.
Create an instance of an FtpFolder which will represent the folder on the FTP server whose content to list. If a folder name is not specified, the folder will represent the current working folder.
Call the FtpFolder's GetItems method to list the contents of the FtpFolder. The contents of the FtpFolder will be listed via the ParsingListingLine event rather than looping through the collection of FileSystemItems returned by the GetItems method.
Dispose of the FtpConnection once the file transfer is completed by calling its Dispose method or, in C#, by creating the FtpConnection instance in a using block. If an instance of an FtpConnection object is not disposed of, connections with the FTP server may remain active until the FTP server times-out or the garbage-collector passes.

VB.NET Copy Code

VB.NET	Copy Code
`Imports Xceed.FileSystem Imports Xceed.Ftp` `Dim connection As FtpConnection` `Try connection = New FtpConnection( "ftp.server.com" ) AddHandler connection.ParsingListingLine, AddressOf Me.parsing_listingline 'When using FtpConnection in a UI application connection.SynchronizingObject = Me` `Dim folder As New FtpFolder( connection ) folder.GetItems( True ) Finally RemoveHandler connection.ParsingListingLine, AddressOf Me.parsing_listingline connection.Dispose() End Try` `Private Sub parsing_listingline( ByVal sender As Object, ByVal e As ParsingListingLineEventArgs ) If ( e.Item.Name = "." ) Or ( e.Item.Name = ".." ) Then e.Valid = False Else System.Diagnostics.Debug.WriteLine( e.Item.Name ) End If End Sub`

Imports Xceed.FileSystem Imports Xceed.Ftp

Dim connection As FtpConnection

Try connection = New FtpConnection( "ftp.server.com" ) AddHandler connection.ParsingListingLine, AddressOf Me.parsing_listingline 'When using FtpConnection in a UI application connection.SynchronizingObject = Me Dim folder As New FtpFolder( connection ) folder.GetItems( True ) Finally RemoveHandler connection.ParsingListingLine, AddressOf Me.parsing_listingline connection.Dispose() End Try

Private Sub parsing_listingline( ByVal sender As Object, ByVal e As ParsingListingLineEventArgs ) If ( e.Item.Name = "." ) Or ( e.Item.Name = ".." ) Then e.Valid = False Else System.Diagnostics.Debug.WriteLine( e.Item.Name ) End If End Sub

C# Copy Code

C#	Copy Code
using Xceed.FileSystem; using Xceed.Ftp; using( FtpConnection connection = new FtpConnection( "ftp.server.com" ) ) { //When using FtpConnection in a UI application connection.SynchronizingObject = this; connection.ParsingListingLine += new ParsingListingLineEventHandler( this.parsing_listingline ); FtpFolder folder = new FtpFolder( connection ); folder.GetItems( true ); connection.ParsingListingLine -= new ParsingListingLineEventHandler( this.parsing_listingline ); } private void parsing_listingline( object sender, ParsingListingLineEventArgs e ) { if( ( e.Item.Name == "." ) \|\| ( e.Item.Name == ".." ) ) { e.Valid = false; } else { System.Diagnostics.Debug.WriteLine( e.Item.Name ); } }

using Xceed.FileSystem;
using Xceed.Ftp;
 
using( FtpConnection connection = new FtpConnection( "ftp.server.com" ) )
{
  //When using FtpConnection in a UI application
  connection.SynchronizingObject = this;

  connection.ParsingListingLine += new ParsingListingLineEventHandler( this.parsing_listingline );
 
  FtpFolder folder = new FtpFolder( connection );
  folder.GetItems( true );       
 
  connection.ParsingListingLine -= new ParsingListingLineEventHandler( this.parsing_listingline );
}  
 
private void parsing_listingline( object sender, ParsingListingLineEventArgs   e )
{
  if( ( e.Item.Name == "." ) || ( e.Item.Name == ".." ) )
  {
    e.Valid = false;
  }
  else
  {
    System.Diagnostics.Debug.WriteLine( e.Item.Name );        
  }  
}

Events

Contrary to other events which are subscribed to by creating an instance of a FileSystemEvents class, the ParsingListingLine event can only be subscribed to via the FtpConnection instance. If any other events are required, an instance of the FileSystemEvents class must be created and the desired events subscribed to.

If you are using FtpConnection in a UI application, assign your form (or any other control that implements the ISynchronizeInvoke interface) to the SynchronizingObject property and call Application.DoEvents in an event.

All methods exposed by the Xceed FileSystem's FileSystemItem, AbstractFolder, AbstractFile, and derived classes have an overload that can be used when events are required.