Copy & Paste WebParts (ASP.NET 2.0 portal framework)

Some developers in the ASP.NET 2.0 Forums have asked questions on how to copy a WebPart (including it's configuration) from one page to another.

The standard solution for this is to use the 'Export/Import' functionality that ASP.NET 2.0 offers for WebParts. Note: for a WebPart to be export-enabled, its 'ExportMode' property should have a value other than 'None' (which is the default) and enableExport="true" should be set in the webParts section of the web.config. The export and import of a (configured) WebPart is done in six steps:

  • Switch to EditDisplayMode
  • Select 'Export' from the verbs menu of the WebPart you want to copy
  • Download the WebPart file to your local PC
  • Navigate to the destination page, switch to CatalogDisplayMode
  • Select the 'Imported Web Part Catalog', and upload the WebPart file
  • Add the uploaded WebPart to a zone

Not very user-friendly, is it? Most users wouldn't even know what to do with the downloaded Webpart file.

However, the ASP.NET 2.0 portal framework is very extensible, so I've build a custom solution where the user can just 'copy' the WebPart to a serverside 'clipboard' (i.e. the Session object), and 'paste' it from a custom Catalog (which I named the 'Copied Web Part Catalog'). So this is done without downloading and uploading WebParts files!

Here's a screenshot of the copy/paste functionality:

So you want to know how this is done? I'll show you the code in 3 parts:

Part 1: Add a custom 'Copy' verb to your WebPart code.

/// <summary>
/// Override the Verbs collection to add the 'copy webpart' verb
/// </summary>
public override WebPartVerbCollection Verbs
{
  get
  {
    if (_verbs == null)
    {
      WebPartVerb myVerb = new WebPartVerb("copy", OnWebPartCopy);
      myVerb.Description = "Copy this WebPart";
      myVerb.Text = "Copy";
      myVerb.ImageUrl = "~/images/CopyVerb.gif";
      _verbs = new WebPartVerbCollection(new WebPartVerb[] { myVerb });
    }
    return _verbs;
  }
}

/// <summary>
/// Called when the user selects 'Copy WebPart' from the verbs menu.
/// The selected WebPart is Exported to a xml string, and added to
/// a list in the Session. This list is used by the CopiedCatalogPart
/// to add the copied WebParts to a new page or zone
/// </summary>
public void OnWebPartCopy(object sender, WebPartEventArgs e)
{
  //get reference to WebPart to copy
  WebPart webPart = e.WebPart;

  //temporarily set ExportMode to 'All' to enable WebPart exporting
  //this is a kind of hack, but assumed legitimate because the exported WebPart
  //stays on the server (in Session) 
  WebPartExportMode origExportMode = ExportMode;
  webPart.ExportMode = WebPartExportMode.All;

  //export WebPart to string
  StringWriter stringWriter = new StringWriter();
  XmlTextWriter xmlwriter = new XmlTextWriter(stringWriter);
  WebPartManager.ExportWebPart(webPart, xmlwriter);
  string copiedWebPart = stringWriter.ToString();
 
  //reset original ExportMode of WebPart
  webPart.ExportMode = origExportMode;

  //reset original ExportMode in exported WebPart string
  XmlDocument doc = new XmlDocument();
  doc.LoadXml(copiedWebPart);
  XmlNode exportModeNode = doc.SelectSingleNode("//property[@name='ExportMode']");
  if (exportModeNode != null)
  {
    exportModeNode.InnerText = this.ExportMode.ToString();
    copiedWebPart = doc.OuterXml;
  }

  //get or create list of copied WebParts
  List<KeyValuePair<string, string>> copiedWebParts;
  if (Context.Session["COPIED_WEBPART_KEY"] != null)
  {
    copiedWebParts = (List<KeyValuePair<string, string>>)
      Context.Session["COPIED_WEBPART_KEY"];
  }
  else
  {
    copiedWebParts = new List<KeyValuePair<string, string>>();
  }

  //insert new copied WebPart as first on list
  copiedWebParts.Insert(0, new KeyValuePair<string, string>(
    string.Format("{0} [copied {1}]", this.Title, DateTime.Now.ToLongTimeString()),
    copiedWebPart));

  //add list to Session
  Context.Session["COPIED_WEBPART_KEY"] = copiedWebParts;
}

Part 2: The CopiedWebPartCatalogPart

using System;
using System.Collections.Generic;
using System.Web.UI.WebControls.WebParts;

namespace myClassLib.CatalogParts
{
  /// <summary>
  /// Catalog for reading WebParts copied to the users Session (copy/paste functionality)
  /// </summary>
  public class CopiedWebPartCatalogPart : CatalogPart
  {
    /// <summary>
    /// Overrides the Title to display "Copied Web Part Catalog" by default
    /// </summary>
    public override string Title
    {
      get
      {
        string title = base.Title;
        return string.IsNullOrEmpty(title) ? "Copied Web Part Catalog" : title;
      }
      set
      {
        base.Title = value;
      }
    }

    //dictionary to hold the availabe copied webparts
    private Dictionary<WebPartDescription, string> _webparts 
      = new Dictionary<WebPartDescription, string>();

    /// <summary>
    /// Returns the WebPartDescriptions for the catalog part
    /// </summary>
    public override WebPartDescriptionCollection GetAvailableWebPartDescriptions()
    {
      _webparts.Clear();
      
      if (Context.Session["COPIED_WEBPART_SESSION_KEY"] != null)
      {
        List<KeyValuePair<string, string>> copiedWebParts = 
          (List<KeyValuePair<string, string>>)Context.Session["COPIED_WEBPART_SESSION_KEY"];
        
        foreach (KeyValuePair<string, string> copiedWebPart in copiedWebParts)
        {
          WebPartDescription desc = new WebPartDescription(
            copiedWebParts.IndexOf(copiedWebPart).ToString(), 
            copiedWebPart.Key,
            null, 
            null);

          _webparts[desc] = copiedWebPart.Value;
        }
      }
      return new WebPartDescriptionCollection(_webparts.Keys);
    }

    /// <summary>
    /// Returns a new instance of the WebPart specified by the description
    /// </summary>
    public override WebPart GetWebPart(WebPartDescription description)
    {
      //get a xmltextreader to the exported WebPart
      System.Xml.XmlTextReader reader =
        new System.Xml.XmlTextReader(new System.IO.StringReader(_webparts[description]));
      string errorMessage; //will contain errorMessage on import errors

      //return an instance of the requested WebPart
      return WebPartManager.ImportWebPart(reader, out errorMessage);
    }
  }
}

Part 3: Add the CopiedWebPartCatalogPart in the CatalogZone of your aspx page

<%@ Register TagPrefix="myCatalogParts" Assembly="myClassLib" Namespace="myClassLib.CatalogParts" %>

<asp:CatalogZone ID="CatalogZone" runat="server" >
  <ZoneTemplate>
    <asp:PageCatalogPart ID="PagePart" runat="server" />
    <asp:ImportCatalogPart Visible="false" ID="ImportPart" runat="Server" />
    <myCatalogParts:CopiedWebPartCatalogPart ID="PastePart" runat="server" />
  </ZoneTemplate>
</asp:CatalogZone>

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