实体框架和纯POCO更新 [英] Entity framework and pure POCO update

问题描述

如何使用实体框架4对纯POCO对象进行更新？

How do I do an update on a pure POCO object using entity framework 4?

我说我更改了该人的名字并以这种方式调用存储库：

Lets say I change the person's first name and call the repository in this manner:

    public User Update(User user)
    {
        //User originalUser = GetUser(user.UserId);

        //Is there a way to update the values that are only changed?

        context.Users.Attach(user);
        context.ObjectStateManager.ChangeObjectState(user, EntityState.Modified);
        return user;
    }

我不希望使用null值将数据库更新为null。例如。假设我有 LastName 作为属性，但是将对象传递给更新函数时，它为null。我是否必须获取originalUser，然后相应地更新每个属性？

I dont want null values to update the database to null. For eg. Suppose I have LastName as a property but when passing the object to the update function, it was null. Am I going to have to get the originalUser and then update each property accordingly?

推荐答案

       "update each property accordingly?"

不，您可以使用，

       context.ObjectStateManager.TryGetObjectStateEntry(newItem, out entity);

      // this will gives you the entity present in db and after that I suggest to write your code to change the state and save.

还建议您阅读此
，以获取有关跟踪 POCO 实体

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