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; }