拥有所有权的类型属性对于EF Core中的已修改实体不持久 [英] Owned type property not persisting for a modified entity in EF Core

问题描述

我正在尝试在EF Core中实现某些对我在EF 6中非常有效的功能.

I'm trying to achieve something in EF Core that worked very well for me in EF 6.

我正在将 List< T> 属性的内容序列化为DB中的Json字符串.< T> 几乎可以是任何东西，因为Json.Net负责序列化我们扔给它的任何东西.我的集合公开了一个 Json 字符串属性，并负责对自身进行序列化/反序列化.

I'm serializing the contents of a List<T> property as a Json string in the DB. <T> can be pretty much anything, since Json.Net takes care of serializing whatever we throw at it. My collection exposes a Json string property and takes care of serializing/deserializing itself.

对于结构化的嵌套数据，这种方法既方便又有效，因为关系模型会带来不必要的开销和复杂性.

This approach is convenient and efficient for structured nested data where a relational model would bring needless overhead and complexity.

在EF 6中，我将执行以下操作:

In EF 6 I would do something like this:

[ComplexType]
public class SelfSerializingCollection<T> : Collection<T>
{
    public void AddRange(IEnumerable<T> collection)
    {
        foreach (var item in collection)
        {
            Add(item);
        }
    }

    protected string Json
    {
        get { return JsonConvert.SerializeObject(this); }
        private set
        {
            Clear();

            if (value == null)
            {
                return;
            }

            AddRange(JsonConvert.DeserializeObject<T[]>(value));
        }
    }
}

EF 6不支持映射泛型类型，因此我们将为可能需要的每种List类型提供具体的实现:

EF 6 doesn't support mapping generic types, so we'd provide a concrete implementation for each type of List we might want:

public class PhoneNumberCollection : SelfSerializingCollection<PhoneNumber> { }

然后像这样使用它:

public class Contact {
    public PhoneNumberCollection PhoneNumbers { get; set; }
}

就是这样.现在，我正在尝试在EF Core 2.0中实现相同的目标.

And that was it. Now, I'm trying to achieve the same in EF Core 2.0.

这是我到目前为止所拥有的. SelfSerializingCollection< T> 类未更改.

Here's what I have so far. The SelfSerializingCollection<T> class is unchanged.

public class Contact {
    // EF Core supports generic types so we don't need a concrete implementation
    // for each collection type.
    public SelfSerializingCollection<PhoneNumber> PhoneNumbers { get; set; }
}

public class MyDbContext : DbContext
{
    // ...

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        // EF Core does not support the [ComplexType] attribute
        // but we now have .OwnsOne() in EF Core 2
        modelBuilder.Entity<Contact>().OwnsOne(p => p.PhoneNumbers);
    }
}

到目前为止，一切都很好.EF Core映射数据库中的 PhoneNumbers_Json 列.读取和创建新条目很好用.

So far so good. EF Core maps the PhoneNumbers_Json column in the DB. Reading and creating new entries works just fine.

但是，与EF 6不同，不对现有实体上的 PhoneNumbers 集合所做的任何更改都不会持久保存到数据库中.我正在使用 _context.Entry(contactModelFromRequestBody).State = EntityState.Modified; 在典型的PUT方法中进行更新-与以前相同.但是由于某种原因，EF Core并未将我的 Json 字符串属性持久保存到数据库中，以用于 Modified 实体.

But, unlike in EF 6, any changes to the PhoneNumbers collection on an existing entity are not being persisted back to the database. I am updating in a typical PUT method with _context.Entry(contactModelFromRequestBody).State = EntityState.Modified; - same as before. But for some reason, EF Core is not persisting my Json string property back to the DB for a Modified entity.

有什么想法吗?

推荐答案

EF Core将拥有的类型像没有自己的身份的实体类型一样对待，因此将指向拥有类型的属性视为导航属性.并且将父实体状态设置为 Modified 不会级联到导航属性.

EF Core treats owned types like entity types w/o own identity, hence properties that point to owned type are treated as navigation properties. And setting the parent entity state to Modified does not cascade to navigation properties.

但是 DbContext 或 DbSet 的 Update 方法确实可以级联，所以代替了

However the Update method of DbContext or DbSet does cascade, so instead of

_context.Entry(contactModelFromRequestBody).State = EntityState.Modified;

您应该使用

_context.Update(contactModelFromRequestBody);

这篇关于拥有所有权的类型属性对于EF Core中的已修改实体不持久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！