EF Table-Per-Type:将新的子项添加到现有父项

Question

我是ASP.NET MVC代码的新手。首先，我实现了一个按类型划分表的层次结构，如下所示：

public abstract class Request
{
    public int RequestId {gets;set;}
    public DateTime CreationDate {get;set;}
    public string CreatedBy {gets;set;}
    public bool Active {Get;set;}
}

public class RequestChildA : Request
{
    public string RequestChildAProp1 {get;set;}
    public string RequestChildAProp2 {get;set;}
    ...
}

public class RequestChildB : Request
{
    public string RequestChildBProp1 {get;set;}
    public string RequestChildBProp1 {get;set;}
    ...
}


Request table
+---------------+-------------------------+------------+--------+
|    RequestId  |       CreationDate      |  CreatedBy | Active | 
+---------------+-------------------------+------------+--------+
| 1             | 2019-08-19 09:40:39.817 | HydroFlask |    1   |
+---------------+-------------------------+------------+--------+

RequestChildA table
+---------------+-------------------------+---------------------+
|    RequestId  |   RequestChildAProp1    |  RequestChildAProp1 | 
+---------------+-------------------------+---------------------+
| 1             |         ValueA          |   ValueB            |
+---------------+-------------------------+---------------------+

ChildA和ChildB可以共享相同的请求。我的问题是，如何将新的ChildB添加到具有现有ChildA的现有请求中。

我已经尝试了通常的方法：

var childB = new childB { RequestChildBProp1 = "Value1", RequestChildBPro2 = "Value2" };
childB.RequestId = 1;
db.RequestChildB.Add(childB);
db.SaveChanges();

它在没有错误的情况下完成，但它创建了一个新请求。我需要一个新的ChildB，是与现有的相同的RequestId。请帮帮我！

我的设计可能是错的，请容忍我。谢谢!

Answer 1

尝试以下未经测试的方法：

public class Request
{
    public int RequestId {gets;set;}
    public DateTime CreationDate {get;set;}
    public string CreatedBy {gets;set;}
    public bool Active {Get;set;}
}

public class RequestChildA
{
    public string RequestChildAProp1 {get;set;}
    public string RequestChildAProp2 {get;set;}
    ...
    public virtual Request Request {get; set;}

}

public class RequestChildB
{
    public string RequestChildBProp1 {get;set;}
    public string RequestChildBProp1 {get;set;}
    ...
    public virtual Request Request {get; set;}
}

Answer 2

我认为你需要像这样创建你的RequestChildA和RequestChildB：

public class RequestChildB
{
    public virtual Request Request {get;set;}

    public string RequestChildBProp1 {get;set;}
    public string RequestChildBProp1 {get;set;}
}

并像这样插入数据：

db.RequestChildB.Add(new RequestChildB
{
    Request = db.Request.Find(1),
    //...other properties
});

db.SaveChanges();