实体框架4 Partialy SaveChanges [英] Entity Framework 4 Partialy SaveChanges

问题描述

说我有这个：

  var entity = db.histories.GetWhere（x => x.Body = =MyBody）。FirstOrDefault（）; 
 var entity2 = db.histories.GetWhere（x => x.Body ==MyBody2）。FirstOrDefault（）; 
 entity.From =lmao！; 
 entity2.From =lmao2！; 
  

现在我知道要更新我必须调用 db.SaveChanges（） ;

我的问题是，如果我只想更新实体，而不是entity2？

是否甚至可能？可以简单的不能确定。

提前感谢。

解决方案

从单独的上下文中获取2个实体：

  var entity = db.histories.GetWhere（x => x.Body ==MyBody）。FirstOrDefault（）; 
 var entity2 = differentDbInstance.histories.GetWhere（x => x.Body ==MyBody2）。FirstOrDefault（）; 
  

或从相同的上下文中检索，但在进行更改之前需要保存

  db.Detach（entity2）; 
 entity2.From =lmao2！; 
  

后者是更好的设计，但您可能需要前者根据场景

Lets say i have this:

var entity = db.histories.GetWhere(x => x.Body == "MyBody").FirstOrDefault();
var entity2 = db.histories.GetWhere(x => x.Body == "MyBody2").FirstOrDefault();
        entity.From = "lmao!";
        entity2.From = "lmao2!";

now i know that to update i have to call db.SaveChanges();

my question is what if i want to update entity only and not entity2 ?

is that even possible ? could be simple im not sure.

thanks in advance.

解决方案

Either get the 2 entities from separate contexts:

var entity = db.histories.GetWhere(x => x.Body == "MyBody").FirstOrDefault();
var entity2 = differentDbInstance.histories.GetWhere(x => x.Body == "MyBody2").FirstOrDefault();        

or retrieve from the same context but detach before making changes you dont want saved

db.Detach(entity2);
entity2.From = "lmao2!";

The latter is better design but you may need to former depending on the scenario

这篇关于实体框架4 Partialy SaveChanges的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！