Question

这可能是我的 la,但我无法找到一个容易的例子。

举我喜欢的电视表演博览仪,我的例子如下:

Table Throne (ThroneID)
Table King (ThroneID)

采用实体框架4,我有两张表格,彼此关系1:1。在法典中,我要将一位国王与一位国王联系起来。国王可以有0或1位国王。如果是1:Many,我有创建协会的Add()。我用的是1:1。

(现在我认识到,我的例子不是最好的......但是,在这个例子中,国王公投会与王牌一样执行1:1)

GameOfThronesContext context = new GameOfThronesContext();
Throne t = new Throne();
King k = new King();
t.Kings.Add(k);  // doesn t work because "Add" isn t available
context.Thrones.AddObject(t);

Answer 1

the solution below if for EF Code First 4.1, it shows how to design the two classes in order to have a relationshiop one-to-zero/one, the result will be:

Throne{Id(PK), Name..}
King {Id(PK,FK), Name..}



public class Throne
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public virtual King King { get; set; }
    }

public class King
{
    public int Id { get; set; }
    public virtual Throne Throne { get; set; }
    public string Name { get; set; }
}

The relationship is then defined in the OnModelCreating of the context or in a configuration class:


public class MyContext : DbContext
{
    public DbSet< Throne> Thrones { get; set; }
    public DbSet< King> Kings { get; set; }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {

        //We define the key for the King table
        modelBuilder.Entity< King>().HasRequired(x => x.Throne);
    }
}

You can then:


 var throne = new Throne(){Name = "First Throne"};
 var king = new King() { Name = "First King" };
 throne.King = king;
 context.Thrones.Add(throne);
 context.SaveChanges();

Answer 2

Updated to reflect OP s comments:

var t = new Throne {
    Id = Guid.NewGuid(),
    //...
    King = new King {
        Id = Guid.NewGuid()
        //...
    }
};

context.Thrones.Add(t);
context.SaveChanges();

EF4.1足以克服制约因素。

Answer 3

因此,我回答了我自己的问题:MS安排了这一问题,以便你在这种情况下必须把父母分配给孩子。《数据实体框架》产生的法典并没有造成出于某种原因将儿童分配给父母的能力。我会发现这一点。以下著作:

GameOfThronesContext context = new GameOfThronesContext();
Throne t = new Throne();
King k = new King();
//t.Kings.Add(k);  // doesn t work because "Add" isn t available
k.Throne = t;  // this is made available by the framework
context.Thrones.AddObject(t);

尽管如此,Gorge2giga表明如何加强这一模式,以便你能够把一名儿童添加到父母身上(我认为),以便你能够使用<代码>。 King = k;,这是我首先想采取的一种更好的解决办法。 Kudos。

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