Entity Framework - 更新detached对象的正确方法

最新推荐文章于 2024-03-05 14:05:13 发布

iteye_20474

最新推荐文章于 2024-03-05 14:05:13 发布

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本文介绍了一种在Entity Framework (EF)中更新Detached对象的方法。通过定义ObjectStateEntry和EntityKey，使用TryGetObjectByKey获取原始对象，并调用ApplyPropertyChanges应用更改。

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今天发现几个同事都不知道在EF中更新detached对象的正确(or 官方)方法：

private
 static
 void
 ApplyItemUpdates(SalesOrderDetail updatedItem)

{
// Define an ObjectStateEntry and EntityKey for the current object.


    EntityKey key;

    object originalItem;

using
 (AdventureWorksEntities advWorksContext =
new
 AdventureWorksEntities())

    {
try


        {
// Create the detached object's entity key.


            key = advWorksContext.CreateEntityKey("SalesOrderDetail"

, updatedItem);

// Get the original item based on the entity key from the context

// or from the database.

if
 (advWorksContext.TryGetObjectByKey(key, out originalItem))

            {
// Call the ApplyPropertyChanges method to apply changes

// from the updated item to the original version.


                advWorksContext.ApplyPropertyChanges
(

                    key.EntitySetName, updatedItem);

            }


            advWorksContext.SaveChanges();

        }
catch
 (InvalidOperationException ex)

        {

            Console.WriteLine(ex.ToString());

        }

    }

}

http://msdn.microsoft.com/en-us/library/bb896248.aspx



关于detached对象以及Attach的解释：

http://msdn.microsoft.com/en-us/library/bb896271.aspx