在表实体框架之间配置多个1到0..1关系

问题描述

以下是今天的早期帖子：

Following on from earlier posts today:

我现在正在尝试配置以下关系：

I'm now trying to configure the following relationships:

Item1具有可选的RawData
Item2具有可选的RawData
Item3具有可选的RawData

Item1 has optional RawDataItem2 has optional RawDataItem3 has optional RawData

RawData必须附加到Item1，Item2或Item3-不应单独存在。

RawData must be attached to either Item1, Item2 or Item3 - it would not be expected to exist on its own.

当前结构为：

class ItemX
{
    [Key]
    public int Id { get; set; }

    public int? RawDataId { get; set; }
    [ForeignKey("RawDataId")]
    public virtual RawData RawData { get; set; }
}

public class RawData
{

    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    //other properties
}

我认为这是可以使用以下命令进行配置：

I thought this might be configured using:

modelBuilder.Entity<Item1>().HasOptional(d => d.RawData).WithOptionalPrincipal().WillCascadeOnDelete(true);
modelBuilder.Entity<Item2>().HasOptional(d => d.RawData).WithOptionalPrincipal().WillCascadeOnDelete(true);
modelBuilder.Entity<Item3>().HasOptional(d => d.RawData).WithOptionalPrincipal().WillCascadeOnDelete(true);

但这给出了以下错误：

这是相同的错误我今天在较早的职位上处理过。在这种情况下，我了解了由于共享主键而无法使用的原因。但是在本例中情况并非如此，因为RawData不能与Item1共享主键，因为Item2可能具有相同的ID。

This is the same error I was dealing with in an earlier post today. In that one I understand the reason it wasn't working due to a shared primary key. But that can't be the case in this example as RawData can't share a primary key with Item1 as Item2 might have the same id.

感谢您的帮助。

编辑

我已经使用：

modelBuilder.Entity<Item1>().HasOptional(d => d.RawData).WithMany().HasForeignKey(d=>d.RawDataId).WillCascadeOnDelete(true);
//etc.

数据库看起来不错。将其描述为WithMany似乎有些奇怪，但这也许是多重关系所必需的？

Database looks ok. Seems a little odd to be describing as WithMany though but perhaps this is what is required when then are multiple relationships??

推荐答案

您需要在RawDataclass中包含Item1，Item2和Item3：

You need to include Item1, Item2, and Item3 in the RawDataclass:

public class RawData
{

    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    public virtual Item1 i1 {get;set;}
    public virtual Item2 i2 {get;set;}
    public virtual Item3 i3 {get;set;}
    //other properties
}

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