How to disabling event firing in SharePoint 2010

Today, I tested whether event receiver fires or not when I use SPListItem's Update methods.
The results are here.


Methods                 event firing
Update()                   fired
SystemUpdate()             fired

SystemUpdate(false)        fired

UpdateOverwriteVersion()   fired

All methods fired !!

But I think people sometimes want not to fire a event receiver when a update method is used.

So, I would like to introduce how to disable event firing.

In SharePoint 2010, SPEventReceiverBase.DisableEventFiring Method and SPEventReceiverBase.EnableEventFiring Method are already obsolete. We need to use EventFiringEnabled Property.

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.speventreceiverbase.disableeventfiring.aspx

A sample code is here.

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1. private void button1_Click(object sender, EventArgs e)  
2. {  
3.     const string siteUrl = "http://sp2010";  
4.     SPSite site = new SPSite(siteUrl);  
5.     SPWeb web = site.RootWeb;  
6.   
7.     SPList list = web.Lists["Announcements"];  
8.     SPListItem item = list.Items[3];  
9.   
10.     HandleEventFiring handleEventFiring = new HandleEventFiring();  
11.     handleEventFiring.DisableHandleEventFiring();  
12.   
13.     try  
14.     {  
15.         item.Update();  
16.     }  
17.     finally  
18.     {  
19.         handleEventFiring.EnableHandleEventFiring();  
20.     }  
21. }  
22.   
23. public class HandleEventFiring : SPItemEventReceiver  
24. {  
25.   
26.     public void DisableHandleEventFiring()  
27.     {  
28.         //obsolete  
29.         //this.DisableEventFiring();  
30.         this.EventFiringEnabled = false;  
31.     }  
32.   
33.     public void EnableHandleEventFiring()  
34.     {  
35.         //obsotete  
36.         //this.EnableEventFiring();  
37.         this.EventFiringEnabled = true;  
38.     }  
39. }  

Enable to execute -ed events synchronously or asynchronously in SharePoint 2010

In SharePoint 2007, -ed events are executed only asynchronously.
This causes some problems between the main thread the and sub thread. For instance, -ed event thread sometimes cannot get its own item's "afterproperties".


Using SharePoint 2010, -ed events can be executed either synchronously or asynchronously.

The two Event Receivers are as follows:

• -ing events (ItemAdding, ListAdding, etc)
• synchronously 
• -ed events (ItemAdded, ListAdded, etc)
• synchronously or asynchronously

You can write "Synchronous" in Elements.xml in SharePoint EventReciver Project in Visual Studio 2010.

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1. <Synchronization>Synchronous</Synchronization>  

Listed below are the steps for making a synchronous -ed event:

• Create project as Event Receiver.

• Choose 2 events (ItemAdding and ItemAdded).

• Write the code. I added the current thread name in ULS log in ItemAdding and ItemAdded method to see status of thread. It is also necessary to add Microsoft.SharePoint.Administration namespace.

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1. using System;  
2. using System.Security.Permissions;  
3. using Microsoft.SharePoint;  
4. using Microsoft.SharePoint.Security;  
5. using Microsoft.SharePoint.Utilities;  
6. using Microsoft.SharePoint.Workflow;  
7. using Microsoft.SharePoint.Administration;  
8.   
9. namespace EventReceiverProject4.EventReceiver1  
10. {  
11.     /// <summary>  
12.     /// List Item Events  
13.     /// </summary>  
14.     public class EventReceiver1 : SPItemEventReceiver  
15.     {  
16.        /// <summary>  
17.        /// An item is being added.  
18.        /// </summary>  
19.        public override void ItemAdding(SPItemEventProperties properties)  
20.        {  
21.            System.Threading.Thread.CurrentThread.Name = "Current Thread";  
22.            string theadName = System.Threading.Thread.CurrentThread.Name;  
23.   
24.            SPDiagnosticsService.Local.WriteTrace(0, new SPDiagnosticsCategory("ItemAdding", TraceSeverity.Unexpected, EventSeverity.Error), TraceSeverity.Unexpected, theadName, theadName);  
25.            base.ItemAdding(properties);  
26.        }  
27.   
28.        /// <summary>  
29.        /// An item was added.  
30.        /// </summary>  
31.        public override void ItemAdded(SPItemEventProperties properties)  
32.        {  
33.            string theadName = System.Threading.Thread.CurrentThread.Name;  
34.            SPDiagnosticsService.Local.WriteTrace(0, new SPDiagnosticsCategory("ItemAdded", TraceSeverity.Unexpected, EventSeverity.Error), TraceSeverity.Unexpected, theadName, theadName);  
35.            base.ItemAdded(properties);  
36.        }  
37.     }  
38. }  

The ItemAdding and ItemAdded thread names are different because ItemAdded is run asynchronously.

The results are shown here:

• ItemAdding's thread name : Current Thread
• ItemAdded's thread name : null

Next, I added <Synchronization>Synchronous</Synchronization> in Elements.xml.

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1. <?xml version="1.0" encoding="utf-8"?>  
2. <Elements xmlns="http://schemas.microsoft.com/sharepoint/">  
3.   <Receivers ListTemplateId="104">  
4.       <Receiver>  
5.         <Name>EventReceiver1ItemAdding</Name>  
6.         <Type>ItemAdding</Type>  
7.         <Assembly>$SharePoint.Project.AssemblyFullName$</Assembly>  
8.         <Class>EventReceiverProject4.EventReceiver1.EventReceiver1</Class>  
9.         <SequenceNumber>10000</SequenceNumber>  
10.         <Synchronization>Synchronous</Synchronization>  
11.       </Receiver>  
12.       <Receiver>  
13.         <Name>EventReceiver1ItemAdded</Name>  
14.         <Type>ItemAdded</Type>  
15.         <Assembly>$SharePoint.Project.AssemblyFullName$</Assembly>  
16.         <Class>EventReceiverProject4.EventReceiver1.EventReceiver1</Class>  
17.         <SequenceNumber>10000</SequenceNumber>  
18.       </Receiver>  
19.   </Receivers>  
20. </Elements>  

The Results are shown here: 

• ItemAdding's thread name : Current Thread
• ItemAdded's thread name : Current Thread