问题描述
我从表单 POST 接收到 LINQ 实体后，尝试将其附加到数据上下文.但是，我得到的只是以下异常:
I am trying to attach a LINQ entity to the data context after I receive it from a form POST. However, all I get is the following exception:
An entity can only be attached as modified without original state if it declares a version member or does not have an update check policy.
我也尝试附加原始行，如下所示:
I have also tried attaching the original row, like so:
dataContext.People.Attach(person, originalPerson);
在这种情况下，我得到以下异常:
In this case, I get the following exception:
Object reference not set to an instance of an object.
这是我的控制器中的代码:
Here's the code in my controller:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(int id, Person person) {
var prevPerson = dataContext.People.Single(p => p.ID == id);
dataContext.People.Attach(person, prevPerson);
dataContext.SubmitChanges();
return Redirect("~/People/Index");
}
对我在这里做错了什么有任何想法吗?如果需要，我可以发布实体代码.
Any ideas on what I'm doing wrong here? I can post the entity code if needed.
推荐答案
在 LinqToSQL 设计器中，将所有更新检查设置为从不，当你附加时，像这样调用它:
In the LinqToSQL designer set all of the Update Checks to Never and when you attach call it like so:
context.entity.Attach(entity, true);
或者，您也可以从数据库中获取实体并使用来自 POSTed 实体的数据对其进行更改，然后将其作为更改提交.
Alternatively, you could also grab the entity from the db and change it using the data from the POSTed entity, then submit that as a change.
这篇关于LINQ 中的实体附件问题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跟版网！