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Introduction

In ASP.NET 2.0, accessing data in web pages is handled through data source controls. These are non-visual controls derived from DataSourceControl. Common examples are the SqlDataSource and the AccessDataSource.

Some time ago, I wanted to make a simple file manager. For this, I needed to list the contents of a folder. I decided to create a custom data source control, so that I could use a GridView control to display the data.

In combination with a GridView, the control can not only show the contents of a folder, but it can also be used to rename or delete files or folders! Therefore, this can be a great control to create your own file manager.

The control can also be used to create a photo gallery with almost no code, as shown below.

The code is in VB.NET, but it's not difficult to get it running in C# or in another language.

License

The control is free and open source under the LGPL license.

Installation

Installing the control

You can install the control in the standard way:

• create a "bin" folder inside the application root of your website (if it's not already there)
• copy the assembly file foldercontentsdatasource.dll into the bin folder

You may want to add the control to the toolbox of your editor (Visual Studio or C# Builder). This will allow you to add the control to a page by dragging it. Follow the editor's procedure to add a control to the toolbox.

Using the control

Adding the control to your page

There are 2 ways to add the control to your page:

1. If the control was installed on the toolbox, add a data control to the page first, such as a GridView, a DataList or a Repeater.
   Next, use the Data Source configuration wizard to choose a data source.
   Make sure there's a copy of the evenlogdatasource.dll assembly in the bin folder.
   
   
2. Add the code manually. Add this line to the top of your page:

   <%@ Register TagPrefix="rw" Namespace="rw" Assembly="foldercontentsdatasourcecontrol" %>

   Then, add a tag like this to your page:

   <rw:FolderContentsDataSource id="FolderContentsDataSource1" runat="server" >
   </rw:FolderContentsDataSource>

   Finally, add the data control (GridView or DataList) to the page, and connect it to the FolderContentsDataSource.

Setting the folder

<rw:FolderContentsDataSource ID="FolderContentsDataSource1" runat="server" >
   <SelectParameters>
      <asp:Parameter Name="Directory" Type="String" DefaultValue="c:\inetpub\wwwroot" />
   </SelectParameters>
</rw:FolderContentsDataSource>

Demo pages

The control comes with two demo pages:

• demo.aspx shows a list of all files and subfolders in a selected folder. This page uses a GridView control, and a Textbox control for selecting a folder. The Directory parameter is set through a ControlParameter, which connects the Textbox to the data source.
• demogallery.aspx shows a gallery with all pictures in a given folder. This page uses a Datalist control bound to the FolderContentsDatasource control. Use the RepeatColumns property of the Datalist to control the number of pictures in a row.

Important: you need to run these pages with credentials that have read rights to the folder. For deleting or renaming files, you need the according permissions. Use impersonation or make sure the folder is accessible for the ASPNET account.

How it works

To build a data source control, I got some ideas from Nikhil Kothari's code at www.nikhilk.net/DataSourceControlsSummary.aspx. I built two main classes FolderContentsDataSource and FolderContentsDataSourceView.

The code reading the folder contents is in the ExecuteSelect method of the FolderContentsDataSourceView class. This code generates a DataTable with a list of entries in the given folder:

Protected Overrides Function ExecuteSelect(ByVal arguments As System.Web.UI.DataSourceSelectArguments) As System.Collections.IEnumerable
    Dim dt As New DataTable()
    dt.Columns.Add("Name", System.Type.GetType("System.String"))
    dt.Columns.Add("Size", System.Type.GetType("System.Int64"))
    dt.Columns.Add("Modified", System.Type.GetType("System.DateTime"))
    dt.Columns.Add("Created", System.Type.GetType("System.DateTime"))
    dt.Columns.Add("Accessed", System.Type.GetType("System.DateTime"))
    dt.Columns.Add("IsFolder", System.Type.GetType("System.Boolean"))

    Dim exc As Exception = Nothing
    Dim dv As DataView = Nothing
    Try
        Dim objFolderContents As DirectoryInfo = New DirectoryInfo(_owner.GetSelectedDirectory())
        Dim objEntries() As FileSystemInfo = objFolderContents.GetFileSystemInfos()
        Dim objEntry As FileSystemInfo
        For Each objEntry In objEntries
            Dim dr As DataRow = dt.NewRow()
            dr("Name") = objEntry.Name
            If (objEntry.Attributes And FileAttributes.Directory) <> 0 Then
                dr("Size") = 0
                dr("IsFolder") = True
            Else
                dr("Size") = CType(objEntry, FileInfo).Length
                dr("IsFolder") = False
            End If
            dr("Modified") = objEntry.LastWriteTime
            dr("Created") = objEntry.CreationTime
            dr("Accessed") = objEntry.LastAccessTime
            dt.Rows.Add(dr)
        Next
        dv = New DataView(dt)
        dv.Sort = arguments.SortExpression
    Catch ex As Exception
        exc = ex
    End Try
    Dim statusEventArgs As New FolderContentsDataSourceStatusEventArgs(exc)
    OnSelected(statusEventArgs)
    If (exc IsNot Nothing And Not statusEventArgs.ExceptionHandled) Then
        Throw exc
    End If
    Return dv
End Function

Points of interest

• Data source control

Future

Here are some ideas for improvement:

• Designer support

If anyone decides to extend this control, or has any comments, bug reports or questions, then it would be great to hear from you.