使用基类查询和Entity Framework TPH模式将更改保存到子类属性 [英] Save changes to child class properties using base class query with Entity Framework TPH patten

问题描述

我有一个简单的TPH层次结构：

I have a simple TPH hierarchy:

public abstract class UserAccount
{
    public string FirstName { get;set; }
}

public class InterpreterAccount : UserAccount
{
    public string PhoneNumber { get;set; }
}

并在DbContext中：

and in DbContext:

//.......
public DbSet<UserAccount> UserAccounts { get; set; }
public DbSet<InterpreterAccount> InterpreterAccounts { get; set; }

此代码有效（将FirstName和PhoneNumber都保存到DB）：

This code works (saves both FirstName and PhoneNumber to DB):

var account = _context.InterpreterAccounts.Single(i => i.Id == id);
account.FirstName = "Ivan";
account.PhoneNumber = "+123";
_context.SaveChanges();

这不会保存PhoneNumber属性

And this doesn't save PhoneNumber property

var account = (InterpreterAccount)_context.UserAccounts.Single(i => i.Id == id);
account.FirstName = "Ivan";
account.PhoneNumber = "+123";
_context.SaveChanges();

但是在实际情况下，对象的类型只有在检索到之后才知道，因此需要

But in real scenarios, the type of object is known only after it is retrieved, hence the need to query the base collection.

所以问题是：我如何保存对通过查询基础对象集合检索的TPH层次结构的派生对象的更改在EF7中？

So the question is: how can I save changes to derived objects of TPH hierarchy retrieved by querying the base object collection in EF7?

推荐答案

...，并在接下来的10分钟内找到了解决方案。

...and found a solution in next 10 minutes. Still looks kinda ugly though.

要保存对通过基础对象集检索的派生对象的更改，我必须1）在查询时分离对象，2）根据以下内容附加到集合

To save changes to derived object retrieved via base object set, I had to 1) detach object on querying and 2) attach to collection based on it's type

var account = _context.UserAccounts.AsNoTracking().Single(i => i.Id == id);
account.FirstName = "Ivan";
if (account is InterpreterAccount)
{
    _context.InterpreterAccounts.Attach(account);
    ((InterpreterAccount)account).PhoneNumber = "+123";
}
_context.SaveChanges();

有效，但是涉及到条件逻辑，这似乎有些过分。我希望没有它就可以使用。

Works but involves conditional logic which seems overkill. I'd like to see it working without it.

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