MOSS 2010:Visual Studio 2010开发体验（14）——列表开发之事件接收器

通过前面几篇，我们已经完成了内容类型，列表定义，列表实例的开发。本篇继续讲解列表中的一个重要环节——事件接收器开发。
我们的场景是：我希望之前做好的订单列表这个内容类型自动地具有某些事件特征，例如当用户在添加一个条目的时候，检查订购日期，如果小于今天的话，就不让添加。（这只是一个假设的场景，现实工作中可以依照业务逻辑而定）
我们应该如何实现这个需求呢？Follow me
1.添加一个事件接收器







下面是默认生成的两个文件








 
     
        OrderItemEventReceiverItemAdding
        ItemAdding
        $SharePoint.Project.AssemblyFullName$
        OrderListSolution.OrderItemEventReceiver.OrderItemEventReceiver
        10000
       

 
2. 修改有关代码实现业务逻辑

using System;
using System.Security.Permissions;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Security;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.Workflow;

namespace OrderListSolution.OrderItemEventReceiver
{
///
/// List Item Events
///
public class OrderItemEventReceiver : SPItemEventReceiver
{
///
/// An item is being added.
///
public override void ItemAdding(SPItemEventProperties properties)
{

SPItemEventDataCollection data = properties.AfterProperties;
SPList list = properties.OpenWeb().Lists[properties.ListId];
string fieldName= list.Fields.GetField("订购日").InternalName;

var date = DateTime.Parse(data[fieldName].ToString());
if (date > DateTime.Now)
{
properties.ErrorMessage = "当前添加的日期不合法";
properties.Cancel = true;
return;

}

}

}
}

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

3.部署和调试，按下F5键





【注意】我们这里故意将订购日设置于大于当前日期。根据事件中的逻辑，我们预期它会报告一个错误，而且取消当前的提交





我们看到了这个错误页面，看起来有些吓人，不是吗？对于一般用户来说，他们可能要被吓坏了

接下来，我们可以定义一个专门的页面来显示错误消息，提高用户体验









然后修改一下代码

using System;
using System.Security.Permissions;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Security;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.Workflow;

namespace OrderListSolution.OrderItemEventReceiver
{
///
/// List Item Events
///
public class OrderItemEventReceiver : SPItemEventReceiver
{
///
/// An item is being added.
///
public override void ItemAdding(SPItemEventProperties properties)
{

SPItemEventDataCollection data = properties.AfterProperties;
SPList list = properties.OpenWeb().Lists[properties.ListId];
string fieldName= list.Fields.GetField("订购日").InternalName;

var date = DateTime.Parse(data[fieldName].ToString());
if (date > DateTime.Now)
{
//properties.ErrorMessage = "当前添加的日期不合法";
properties.Status = SPEventReceiverStatus.CancelWithRedirectUrl;
properties.RedirectUrl = "/_layouts/OrderListSolution/ErrorPage.aspx";
properties.Cancel = true;

}

}

}
}

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }