如何使用Entity Framework 5更新记录 [英] How Do I Update A Record Using Entity Framework 5

问题描述

我正在使用实体框架工作5数据库第一个工作流程，只是我的第一次尝试，我正在尝试更新记录属性，但它似乎不起作用，错误消息是：



属性'device_name'是对象的关键信息的一部分，无法修改



这里是我的代码：

i am using entity frame work 5 database first workflow, just my first attempt, i am trying to update a record attribute, but it doesn't seem to work, the error message is:

the property 'device_name' is part of the object's key information and cannot be modified

here is my code:

device dev = dbEntities.devices.First( i => i.id==1 );
                dev.device_name="newUpdateValue";

                dbEntities.SaveChanges( );

也试过这个：

also tried this:

protected int UpdateMethod(int Id, string newValue,string modelNumber)
       {
           using (var ctx = new GSC_NewSchoolCoreEntities( ) )
           {
               var query = ( from q in ctx.devices
                             where q.id  == Id
                             select q ).First( );
                   query.device_name  = newValue;
                   query.model_number= modelNumber;
                   int result = ctx.SaveChanges( );
                   return result;
           }
       }

通话方式：

the calling method:

UpdateMethod( DeviceID, DeviceName, ModelNumber );

仍然有相同的错误消息，我在网上搜索，看看我是否可以自己修复，但没有一个在线解决方案适合我！ device_name和model_number是我想要更新但不是id，请问我有什么遗漏？感谢您的贡献。

still having the same error message, i have search online to see if i could fix this myself, but none of the online solutions work for me! device_name and model_number are what i want to update but not the id, Please is there anything i am missing? Thanks for your contributions.

推荐答案

检查您的表是否在数据库中具有主键列。如果它没有任何主键而不是添加主键。因为如果我们不向表添加主键，那么实体框架会创建自己的密钥集合并在其中添加所有列。

有关更多信息，请查看以下链接

< a href =http://blogershub.com/Archive/2013/10/The-property-is-part-of-the-object-key-information-and-cannot-be-modified#.U8jk_fmSwwk> http： //blogershub.com/Archive/2013/10/The-property-is-part-of-the-object-key-information-and-cannot-be-modified#.U8jk_fmSwwk [ ^ ]

Check whether your table is having primary key column in database or not. If it does not have any primary key than add a primary key. Because if we don't add a primary key to table than entity framework creates its own key collection and add all columns in it.
For more check the following link
http://blogershub.com/Archive/2013/10/The-property-is-part-of-the-object-key-information-and-cannot-be-modified#.U8jk_fmSwwk[^]

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