MOSS 2007 Tips and Trick January 2008

Here are some MOSS 2007 tips I want to share from my previous experience.

Problem : How to insert / update a list item without write permission

You can use this code

SPSecurity.RunWithElevatedPrevileges(delegate(){
//place your code here
});

Your code above will be executed using admin rights. So you can insert / update a list item even though current login doesn't have permission to insert / update.

Note:
Remind that you cannot call method Update of SPListItem class inside the code above. It will throw error like this : "Operation is not valid due to the current state of the object".

I have googled about this problem and found a way to solve it, thanks to this great post.
The point is :You must not call the SPListItem.Update inside the RunWithElevatedPrivileges block. Instead you should only instantiate the SPSite or SPWeb there and call Update afterwards.

Here is the sample code :

  SPSite site = new SPSite("http://moss.denallix.com");
  SPWeb elevatedRootWeb = null;
  SPWeb web = site.OpenWeb();
  SPSecurity.RunWithElevatedPrivileges(delegate()
  {
     using (SPSite elevatedSite = new SPSite(web.Site.ID))
     {
         elevatedRootWeb = elevatedSite.RootWeb;
     }
  });
  SPList myList = elevatedRootWeb.Lists["MyList"];
  try
  {
     elevatedRootWeb.AllowUnsafeUpdates = true;
     SPListItem myNewItem = myList.Items.Add();
     myNewItem["Column1"] = "Column1Value";
     myNewItem["Column2"] = "Column2Value";
     myNewItem["Column3"] = "Column3Value";
     myNewItem.Update();
  }
  catch (Exception ex)
  {
     EventLog.WriteEntry("Error", ex.Message.ToString(), EventLogEntryType.Error);
  }

MOSS 2007 Tips : Dynamic Webpart Installer Class

Usually when we deploy a web part to MOSS , we have to develop 2 times. One for the installer class , one for the user control (ASCX) itself. A friend of mine has made a dynamic installer class so that we just have to set the ASCX path every time we want to make a web part. Here is the code.

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

namespace DynamicUserControlWebPart
{
    public class DynamicUserControlWebPart : WebPart
    {
        private string _usercontrolvirtualpath;
        private string ErrorMessage;
        Control _control = null;

        [WebBrowsable(true)]
        [Personalizable(true)]
        [WebDescription("Dynamic User Control WebPart")]
        [WebDisplayName("Dynamic User Control WebPart")]
        public string UserControlVirtualPath
        {
            get { return _usercontrolvirtualpath; }
            set { _usercontrolvirtualpath = value; }
        }

        protected override void CreateChildControls()
        {
            this.Controls.Clear();
            try
            {
                _control = this.Page.LoadControl(_usercontrolvirtualpath);
                this.Controls.Add(_control);
            }
            catch (System.Exception ex)
            {
                ErrorMessage = ex.Message;
            }
        }

        protected override void RenderChildren(HtmlTextWriter writer)
        {
            if (_control != null)
            {
                _control.RenderControl(writer);
            }
            else
            {
                writer.Write(ErrorMessage);
            }
        }
    }
}

- Deploy this Web Part.
- Place your *.ASCX and *.ASCX.CS files in the moss folder (ex: C:\Inetpub\wwwroot\wss\VirtualDirectories\81\MyUserControl ).
- After adding this webpart to a page , just click Edit - Modify Shared Web Part.
- And then set the ASCX path to the property in the right column , Miscellaneous category. (ex : ~/MyUserControl/myUC.ascx )
- See the result.