如何更新实体？ [英] How to update entity?

问题描述

我有一个问题，前面我没有回答比较详细，我将有一个更简单的方法同样的问题：

我有外键到另一个表的EF数据库。

我想为更新的 实体的。但我需要这种类似这样的，我会写$ C $以下CS：

1. 转到数据库和获取按ID会员，返回EF成员对象


2. 请在对象上的一些变化的 OUTSIDE 的EF上下文


3. 将体改 EF会员进入Save方法


4. 在BL层保存方法使用上下文并保存更改。

1）

  MemberManager currentMemberManager =新MemberManager（）;
构件NewMember = currentMemberManager.GetById（2）;
 

2）

  NewMember.FirstName =NewFirstName;
NewMember.LanguageId = 1;
 

3）

  currentMemberManager.Save（NewMember）;
 

4）

 公共无效SAVE2（会员newMember）
{
    使用（VAR上下文=新NoxonEntities（））
    {
        会员existingMember = Context.Member.First（C =＆GT; c.Id == newMember.Id）;
        existingMember.FirstName = newMember.FirstName;
        existingMember.Language = Context.Language.First（C =＆GT; c.Id == newMember.LanguageId）;
        Context.SaveChanges（）; //在这里我得到下面的错误
    }
}
 

  

到数据库的变化成功提交，但一个错误
  在更新对象上下文发生。该ObjectContext的可能
  在不一致的状态。内部异常消息：引用
  完整性约束冲突发生了：该属性值是
  定义参照约束不是之间是一致的
  本金和依赖对象的关系。

  
  

注意：您可以建议发送一个不同的类（例如：公共类
  MyMember）具有所有必要的属性和完全分开
  从EF。但是，这需要大量的工作来获得所有EF对象转换
  进入我的单独的类。我说得对不对？

我希望有一种方法来分离实体足够长的时间让我修改和值保存到数据库中。 （另外，我试过分离方法，在所有的更新没有行）

我一直在试图解决现在这个好几个小时。

请，帮助我更好地理解它，我真的需要一个解决方案。非常感谢你对任何人如何有一些想法。

解决方案

您可以做一些简单的像分离实体，然后将其连接到上​​下文当你准备好保存？

  MemberManager currentMemberManager =新MemberManager（）;
构件NewMember = currentMemberManager.GetById（2）;
 

的get：

  public成员GetById（INT ID）
{
  变种构件= YourContext.Members.FirstOrDefault（M =＆GT; m.id == ID）;
  YourContext.Detach（会员）;
  返回成员;
}
 

保存：

 公共无效SAVE2（会员newMember）
        {
            使用（VAR上下文=新NoxonEntities（））
            {
                Context.Attach（newMember）;
                Context.ObjectStateManager.ChangeObjectState（newMember，EntityState.Modified）;
                Context.SaveChanges（）;
            }
        }
 

I had a question more detailed earlier which I had no answer, I will have the same question with a simpler way:

I have an EF database with foreign key to another table.

I would like to UPDATE an ENTITY. But I need to this like this and I'll write the codes below:

1. Go to database and retrieve the Member by id, return EF Member object
2. Do some changes on the object OUTSIDE the EF Context
3. Send the MODIFED EF Member into a Save method
4. In BL layer save method uses the context and save changes.

1)

MemberManager currentMemberManager = new MemberManager();
Member NewMember = currentMemberManager.GetById(2);

2)

NewMember.FirstName = "NewFirstName";
NewMember.LanguageId = 1;

3)

currentMemberManager.Save(NewMember);

4)

public void Save2(Member newMember)
{
    using (var Context = new NoxonEntities())
    {
        Member existingMember = Context.Member.First(c => c.Id == newMember.Id);
        existingMember.FirstName = newMember.FirstName;
        existingMember.Language = Context.Language.First(c => c.Id == newMember.LanguageId);
        Context.SaveChanges();//In here I get the error below
    }
}

The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: A referential integrity constraint violation occurred: The property values that define the referential constraints are not consistent between principal and dependent objects in the relationship.

Note: You may suggest to SEND a different class (Ex: public class MyMember) that has all the necessary properties and totally separated from EF. But this requires much work to get all EF object converting into my separate classes. Am I right?

I am hoping there is a way to Detach the entity just long enough for me to modify it and save the values into database. (Also, I tried the Detach method which updates no rows at all)

I've been trying to solve this for hours now.

Please, help me to understand it better, I really need a solution. Thank you so much to anyone how has some ideas.

解决方案

Could you do something simple like detaching the entity, then attaching it to the context when you're ready to save?

MemberManager currentMemberManager = new MemberManager();
Member NewMember = currentMemberManager.GetById(2);

The get:

public Member GetById(int id)
{ 
  var member = YourContext.Members.FirstOrDefault(m => m.id == id);
  YourContext.Detach(member);
  return member;
}

The save:

public void Save2(Member newMember)
        {
            using (var Context = new NoxonEntities())
            {
                Context.Attach(newMember);
                Context.ObjectStateManager.ChangeObjectState(newMember, EntityState.Modified);
                Context.SaveChanges();
            }
        }

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