I created this list event receiver blog just for an example and to clear few basic questions I had. I have created using Visual Studio 2010 and for SharePoint 2010 list, however, this would be same for SharePoint 2007, you can check my other blog for further reference.
The steps
1. In visual studio select Event Receiver project .
2. Give a name like – ListDeleteEventReceiver select the type of list (Generic list
3. In the SharePoint Customization Wizard, select the An item is being deleted option, and then click Finish.
4. Then open the Elements.xml file.
5. To make sure that the event receiver only binds to the custom list, ensure the ListTemplateId attribute in the Receivers element is set to 100.
<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<Receivers ListTemplateId="100" >
<Receiver>
<Name>EventReceiver1ItemDeleting</Name>
<Type>ItemDeleting</Type>
<Assembly>$SharePoint.Project.AssemblyFullName$</Assembly>
<Class>ListDeleteEventReceiver.ListItemDeleteER.ListItemDeleteER</Class>
<SequenceNumber>10000</SequenceNumber>
</Receiver>
</Receivers>
</Elements>
6. In Solution Explorer, expand open ListItemDeleteER.cs class file. You should see the overridden ItemDeleting method.
7. Insert the following code into the body of ItemDeleting method after the base.ItemDeleting(properties); statement. This code prevents the deletion of an item and display an error message.
public class ListItemDeleteER : SPItemEventReceiver
{
/// <summary>
/// An item is being deleted.
/// </summary>
public override void ItemDeleting(SPItemEventProperties properties)
{
base.ItemDeleting(properties);
try
{
properties.Cancel = true;
properties.ErrorMessage = "Item cannot not be deleted!";
}
catch (Exception ex)
{
return;
}
finally
{
this.EventFiringEnabled = true;
}
}
}
Deploy and check.
The most important point here is the how this works.
1. How this event receiver would be targeted for my specific list?
2. If I do not mention my target list then what?
To Answer these questions, I would refer to the Elements.xml file. Since I have mentioned only <Receivers ListTemplateId="100" >.
This would target all lists with template id 100 (refer below for all the list template ids). I will not be able to delete items from any generic list .
Now to make it target a specific list we handle this in various ways. I have mentioned the easiest one and have mentioned the rest, which I will try to put in later.
1. Change in the elements.xml.
<Receivers ListUrl="Lists/TestER" >
Can loop in the override method get the list and check column and do the rest
public override void ItemDeleting(SPItemEventProperties properties)
{
base.ItemDeleting(properties);
try
{
SPList mylist = properties.List;
Do the logic here……..
properties.Cancel = true;
properties.ErrorMessage = "deleted!";
}
catch (Exception ex)
{
return;
}
finally
{
this.EventFiringEnabled = true;
}
}
List Template Ids
The ListTemplateId defines to which List Types the Event Handler will be targeting. The table below shows which list types there are available in SharePoint
| ID | Name |
| 100 | Generic list |
| 101 | Document library |
| 102 | Survey |
| 103 | Links list |
| 104 | Announcements list |
| 105 | Contacts list |
| 106 | Events list |
| 107 | Tasks list |
| 108 | Discussion board |
| 109 | Picture library |
| 110 | Data sources |
| 111 | Site template gallery |
| 112 | User Information list |
| 113 | Web Part gallery |
| 114 | List template gallery |
| 115 | XML Form library |
| 116 | Master pages gallery |
| 117 | No-Code Workflows |
| 118 | Custom Workflow Process |
| 119 | Wiki Page library |
| 120 | Custom grid for a list |
| 130 | Data Connection library |
| 140 | Workflow History |
| 150 | Gantt Tasks list |
| 200 | Meeting Series list |
| 201 | Meeting Agenda list |
| 202 | Meeting Attendees list |
| 204 | Meeting Decisions list |
| 207 | Meeting Objectives list |
| 210 | Meeting text box |
| 211 | Meeting Things To Bring list |
| 212 | Meeting Workspace Pages list |
| 300 | Portal Sites list |
| 301 | Blog Posts list |
| 302 | Blog Comments list |
| 303 | Blog Categories list |
| 1100 | Issue tracking |
| 1200 | Administrator tasks list |
| 2002 | Personal document library |
| 2003 | Private document library |
If you have a more elegant solution – please post a comment… I’ll be happy to hear.
...HaPpY CoDiNg
Partha (Aurum)
Reference:
http://koenvosters.wordpress.com/2009/07/31/howto-create-an-event-handler-for-sharepointmoss-2007/
http://msdn.microsoft.com/en-us/library/ms475328(office.12).aspx
http://msdn.microsoft.com/en-us/library/ff728093.aspx
http://apartha77.blogspot.com/2011/04/deploying-item-event-receiver.html
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