SharePoint - 功能/事件接收器

在本章中，我们将学习添加代码句柄。代码句柄是在激活或停用功能时触发的事件。换句话说，我们将检查功能接收器。

我们在上一章创建的 Visual Studio 项目包含一个功能，当它被激活时，它会预配我们的联系人列表、我们的网站页面以及到网站页面的链接。

但是，当功能被停用时，SharePoint 只删除链接，网站页面和联系人列表仍然保留。

如果我们想要，我们可以在停用功能时编写代码以删除列表和页面。在本章中，我们将学习如何在停用功能时删除内容和元素。

要处理功能的事件，我们需要一个功能接收器。

步骤 1 - 要获取功能接收器，请右键单击解决方案资源管理器中的功能，然后选择添加事件接收器。

using System;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using Microsoft.SharePoint;

namespace FeaturesAndElements.Features.Sample {
   /// <summary>
      /// This class handles events raised during feature activation, deactivation,
         installation, uninstallation, and upgrade.
   /// </summary>
   /// <remarks>
      /// The GUID attached to this class may be used during packaging and should not be modified.
   /// </remarks>
   [Guid("e873932c-d514-46f9-9d17-320bd3fbcb86")]
  
   public class SampleEventReceiver : SPFeatureReceiver {
      // Uncomment the method below to handle the event raised after a feature has been activated.
      //public override void FeatureActivated(SPFeatureReceiverProperties properties)//{
         //
      }
      // Uncomment the method below to handle the event raised before a feature is deactivated.
      //public override void FeatureDeactivating(SPFeatureReceiverProperties properties)// {
         //
      }
      // Uncomment the method below to handle the event raised after a feature has been installed.
      //public override void FeatureInstalled(SPFeatureReceiverProperties properties)// {
         //
      }
      // Uncomment the method below to handle the event raised before a feature is uninstalled.
      //public override void FeatureUninstalling(SPFeatureReceiverProperties properties)// {
         //
      }
      // Uncomment the method below to handle the event raised when a feature is upgrading.
      //public override void FeatureUpgrading(SPFeatureReceiverProperties
         properties, string upgradeActionName,
         System.Collections.Generic.IDictionary<string, string> parameters) // {
         //
      }
   }
}

您可以看到我们得到的是一个从SPFeatureReceiver继承的类。

在 SharePoint 中，有不同的类用于您可以处理的不同类型的事件。例如，列表上的事件、列表项上的事件、网站上的事件。您可以创建一个从特定事件接收器派生的类，然后您可以覆盖该类中的方法来处理事件。

功能的事件在以下情况下使用 -

激活
停用
安装
卸载
升级

接下来，您需要将该类作为特定项目的事件处理程序附加。例如，如果有一个处理列表事件的事件处理程序，则需要将该类附加到列表。

因此，我们将处理两个功能 -

功能激活时
功能停用时。

步骤 2 - 我们将实现FeatureActivated 和 FeatureDeactivated 方法，如下所示 -

using System;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using Microsoft.SharePoint;

namespace FeaturesAndElements.Features.Sample {
   /// <summary>
      /// This class handles events raised during feature activation, deactivation,
         installation, uninstallation, and upgrade.
   /// </summary>
   /// <remarks>
      /// The GUID attached to this class may be used during packaging and should
         not be modified.
   /// </remarks>

   [Guid("e873932c-d514-46f9-9d17-320bd3fbcb86")]
   public class SampleEventReceiver : SPFeatureReceiver {
      private const string listName = "Announcements";
      
      public override void FeatureActivated(SPFeatureReceiverProperties properties) {
         var web = properties.Feature.Parent as SPWeb;
         
         if (web == null) return;
         var list = web.Lists.TryGetList(listName);
         
         if (list != null) return;
         var listId = web.Lists.Add(listName, string.Empty,
         SPListTemplateType.Announcements);
         list = web.Lists[listId];
         list.OnQuickLaunch = true;
         list.Update();
      }
      public override void FeatureDeactivating(SPFeatureReceiverProperties properties) {
         var web = properties.Feature.Parent as SPWeb;
         
         if (web == null) return;
         var list = web.Lists.TryGetList(listName);
         
         if (list == null) return;
         if (list.ItemCount == 0) {
            list.Delete();
         }
      }
   }
}

注意 -