带有ADO.NET实体框架的强类型ASP.NET MVC

Question

经过几天的奋斗,我终于得到了这份工作.

我有一个简单的人员和部门数据库:

带有Department和Person对象的ADO.NET实体框架实体数据模型图http://img39.imageshack.us/img39/1368/edmxdepartmentperson.gif

我可以使用强类型的ASP.NET MVC视图作为参考/导航属性!查看部门列表......

带有DropDownList的ASP.NET MVC http://img11.imageshack.us/img11/7619/dropdownlistdepartment.gif

我的人物/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Person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");
}

为了实现这一点,我使用新的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", "Id", value);
            }
        }
    }
}

我使用新的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, "Id", 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;
            }
        }
    }

}

我只想在这里记录我的进展.请提出改进​​建议.

---

谢谢:

• Alex James
• 塞萨尔德拉托雷
• 格里夫汤森
• 史蒂夫威尔科克
• jrista
• 托马斯莱肯
• 托马斯莱维斯克
• 丹尼西蒙斯
• Stefan Cruysberghs

Answer 1

我已经开始使用ASP.NET MVC,这就是为什么我遇到这个帖子,所以我不确定你是否还在检查改进.

我不喜欢将新属性添加到实体框架的部分类中的想法,因为它不允许进行那么多的更改.尝试像这样标记你的Deparment DropDown"Department.Id"

<p>
    <label for="Department.Id">Department:</label>
<%= Html.DropDownList("Department.Id", new SelectList((IEnumerable)ViewData["Departments"], "Id", "Name"))%>
</p>

MVC框架的ModelBinding将获取值并将其应用于"Department"导航属性的"Id"属性.我发现Department的其他值是null,但这并不重要.现在,您可以检索正确的Department Entity并将其应用于在Model Bind中创建的新Person Entity的Department Navigation Property中的Action参数,如:

newPerson.Department = ctx.Department.First(d => d.DepartmentId == newPerson.Department.Id);

通过这种方式,您根本不需要为其应具有的属性更新您的实体.