经过几天的斗争,我终于得到了这个工作.
我有一个简单的人员和部门数据库：
我可以使用强类型的ASP.NET MVC视图参考/导航属性！查看部门清单…
ASP.NET MVC with DropDownList http://img11.imageshack.us/img11/7619/dropdownlistdepartment.gif
我的人/编辑视图的一部分：
<% using (Html.BeginForm()) {%>
<%= Html.Hidden("Id",Model.Id) %>
<fieldset>
<legend>Fields</legend>
<p>
<label for="Name">Name:</label>
<%= Html.TextBox("Name",Model.Name) %>
</p>
<p>
<label for="DepartmentId">Department:</label>
<%= Html.DropDownList("DepartmentId",new SelectList((IEnumerable)ViewData["Departments"],"Id","Name"))%>
</p>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
<% } %>
我的人员控制器的一部分：
//
// GET: /Person/Edit/5
public ActionResult Edit(Guid id)
{
ViewData["Departments"] = ctx.Department;
Person model = (from Person p in ctx.Person
where p.Id == id
select p).FirstOrDefault();
return View(model);
}
//
// POST: /Person/Edit
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(Person model)
{
ctx.AttachUpdated(model); //extension
ctx.SaveChanges();
return RedirectToAction("Index");
}
为了得到这个工作,我用一个新的DepartmentId属性扩展了Person EntityObject.
using System;
using System.Data;
using System.Data.Objects.DataClasses;
namespace ProjectName.Models
{
public partial class Person : EntityObject
{
public Guid DepartmentId
{
get
{
try
{
return (Guid)this.DepartmentReference.EntityKey.EntityKeyValues[0].Value;
}
catch
{
return Guid.Empty;
}
}
set
{
this.DepartmentReference.EntityKey = new EntityKey("JunkEntities.Department",value);
}
}
}
}
并且我用新的AttachUpdated和ApplyReferencePropertyChanges方法扩展了Entity Framework ObjectContext：
using System;
using System.Data;
using System.Data.Objects;
using System.Data.Objects.DataClasses;
public static class EntityFrameworkExtensionMethods
{
public static void AttachUpdated(this ObjectContext ctx,EntityObject objectDetached)
{
if (objectDetached.EntityKey == null)
{
String entitySetName = ctx.DefaultContainerName + "." + objectDetached.GetType().Name;
Guid objectId = (Guid)objectDetached.GetType().GetProperty("Id").GetValue(objectDetached,null);
objectDetached.EntityKey = new System.Data.EntityKey(entitySetName,objectId);
}
if (objectDetached.EntityState == EntityState.Detached)
{
object currentEntityInDb = null;
if (ctx.TryGetObjectByKey(objectDetached.EntityKey,out currentEntityInDb))
{
ctx.ApplyPropertyChanges(objectDetached.EntityKey.EntitySetName,objectDetached);
ctx.ApplyReferencePropertyChanges((IEntityWithRelationships)objectDetached,(IEntityWithRelationships)currentEntityInDb); //extension
}
else
{
throw new ObjectNotFoundException();
}
}
}
public static void ApplyReferencePropertyChanges(this ObjectContext ctx,IEntityWithRelationships newEntity,IEntityWithRelationships oldEntity)
{
foreach (var relatedEnd in oldEntity.RelationshipManager.GetAllRelatedEnds())
{
var oldRef = relatedEnd as EntityReference;
if (oldRef != null)
{
var newRef = newEntity.RelationshipManager.GetRelatedEnd(oldRef.RelationshipName,oldRef.TargetRoleName) as EntityReference;
oldRef.EntityKey = newRef.EntityKey;
}
}
}
}
我只想记录我在这里的进度.请建议改进.
谢谢：
> Alex James
> Cesar de la Torre
> Griff Townsend
> Steve Willcock
> jrista
> Tomas Lycken
> Thomas Levesque
> Danny Simmons
> Stefan Cruysberghs
解决方法
我已经开始使用ASP.NET MVC,这就是为什么我来到这个线程,所以我不知道你是否仍在检查改进.
我不喜欢将这个新属性添加到实体框架上的部分类中,因为它不允许有太多变化.
尝试标记你的Deparment DropDown“Department.Id”这样
<p>
<label for="Department.Id">Department:</label>
<%= Html.DropDownList("Department.Id","Name"))%>
</p>
MVC框架的ModelBinding将获取该值并将其应用于“部门”导航属性的“Id”属性.我发现部门的其他价值是空的,但这并不重要.现在,您有一种方法来检索正确的部门实体并将其应用于在“绑定到您的Action”参数中创建的新Person实体的部门导航属性,如下所示：
newPerson.Department = ctx.Department.First(d => d.DepartmentId == newPerson.Department.Id);
这样做,您不需要更新您的实体,因为它应该具有的属性.
