使用EF 4.1将父记录和多个子记录作为单个"工作单元"插入

Question

我正在练习代码优先的类,它们之间有父子关系.

public class Parent
{
    public int Id ( get; set; }
    public string Name { get; set; }
    public List<Child> Children { get; set; }

    public Parent()
    {
        Children = new List<Child>();
    }
}

public class Child()
{
    public int Id ( get; set; }
    public string Name { get; set; }
}

public class MyContext : DbContext
{
    public DbSet<Parent> Parents { get; set; }
    public DbSet<Child> Children { get; set; }
}

在一个简单的控制台应用程序中,我创建一个父级并创建两个子记录并将它们添加到父级.如果我然后调用SaveChanges(),则只将第一个子项添加到children表中.

var x = new MyContext();

var c1 = new Child { Name = "Alpha-Child" };
var c2 = new Child { Name = "Beta-Child" };

var p = new Parent {Name = "Alpha-Parent"};

p.Children.Add(c1);
p.Children.Add(c2);

x.Parents.Add(p);

x.SaveChanges();

那不是我想要的,所以我试图将其添加到父对象和上下文对象.

var x = new MyContext();

var c1 = new Child { Name = "Alpha-Child" };
var c2 = new Child { Name = "Beta-Child" };

var p = new Parent {Name = "Alpha-Parent"};

p.Children.Add(c1);
p.Children.Add(c2);

x.Children.Add(c1);
x.Children.Add(c2);

x.Parents.Add(p);

x.SaveChanges();

这使得子记录进入数据库,但只有其中一个(第一个)与父记录相关联.

最后,但并非最不重要的是,我在每次调用Parent.Add()之后尝试调用SaveChanges().

var x = new MyContext();

var c1 = new Child { Name = "Alpha-Child" };
var c2 = new Child { Name = "Beta-Child" };

var p = new Parent {Name = "Alpha-Parent"};

x.Parents.Add(p);

p.Children.Add(c1);
x.SaveChanges();

p.Children.Add(c2);
x.SaveChanges();

但是,这打破了我对"工作单元"模式如何运作的看法.我"应该能够调用SaveChanges()一次,并且我的所有更改都发生了,对吗？

那么,我做错了什么？

Answer 1

以下代码将保存在单个保存更改中.并始终使用事务处理器以单批存储.

public class Child 
{
  public int Id ( get; set; }
  public string Name { get; set; }
  public Parent Parent {set;get;}
}


var x = new MyContext();
var c1 = new Child { Name = "Alpha-Child" };
var c2 = new Child { Name = "Beta-Child" };

var p = new Parent {Name = "Alpha-Parent"};
c1.Parent = p;
c2.Parent = p;
x.Parents.Add(p);
x.SaveChanges();