[英]Code first: One to many relationship of the same entity
I have an Entity Product
which can have multiple additional products. 我有一个实体Product
,可以有多个其他产品。 So what I need is a junction table to map a Product
to additional Product
s. 因此,我需要一个联结表将一个Product
映射到其他Product
。
What I tried to do is the following: 我试图做的是以下几点:
[Table("Product")]
public class Product : EntityBase
{
[Key]
public int Id { get; set; }
public virtual ICollection<Argument> Arguments { get; set; }
public virtual ICollection<Product> AdditionalProducts { get; set; }
}
Add a collection of Products, hoping that EF would build a junction table. 添加产品集合,希望EF可以建立联结表。 However I end up with this in my migration: 但是,在迁移过程中最终遇到了这个问题:
public partial class test1 : DbMigration
{
public override void Up()
{
AddColumn("dbo.Product", "Product_Id", c => c.Int());
CreateIndex("dbo.Product", "Product_Id");
AddForeignKey("dbo.Product", "Product_Id", "dbo.Product", "Id");
}
public override void Down()
{
DropForeignKey("dbo.Product", "Product_Id", "dbo.Product");
DropIndex("dbo.Product", new[] { "Product_Id" });
DropColumn("dbo.Product", "Product_Id");
}
}
What am I doing wrong here? 我在这里做错了什么?
As you said in the comment that: 正如您在评论中所说:
A product can be an additional product to multiple products. 一个产品可以是多个产品的附加产品。 And can also have its set of additional products. 并且还可以拥有其一套其他产品。
So, First make a model class named AdditionalProduct
as follows: 因此,首先制作一个名为AdditionalProduct
的模型类,如下所示:
[Table("AdditionalProduct")]
public class AdditionalProduct
{
[Key]
public int Id { get; set; }
public int ProductId {get; set;}
public int AdditionalProductId {get; set;}
public Product Product {get; set;}
public Product AdditionalProduct {get; set;}
}
And your Product
class should as follows: 并且您的Product
类应如下所示:
[Table("Product")]
public class Product : EntityBase
{
[Key]
public int Id { get; set; }
.......
public virtual ICollection<AdditionalProduct> HisAdditionalProducts { get; set; }
public virtual ICollection<AdditionalProduct> AdditionalProductsTo { get; set; }
}
Then in the OnModelCreating
as follows: 然后在OnModelCreating
中如下所示:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<AdditionalProduct>()
.HasRequired(m => m.Product)
.WithMany(t => t.HisAdditionalProducts)
.HasForeignKey(m => m.ProductId)
.WillCascadeOnDelete(false);
modelBuilder.Entity<AdditionalProduct>()
.HasRequired(m => m.AdditionalProduct)
.WithMany(t => t.AdditionalProductsTo)
.HasForeignKey(m => m.AdditionalProductId)
.WillCascadeOnDelete(false);
}
The great solution for you is: 您的最佳解决方案是:
First, make a new class for all your Aditional Productions
首先,为您的所有Aditional Productions
新的班级
[Table("AdditionalProducts")]
public class AdditionalProduct
{
[Key]
public int Id { get; set; }
public virtual ICollection<Product> AdditionalProducts { get; set; }
}
Second, create a relationship
one-to-one
to this class 其次,与该类one-to-one
建立relationship
[Table("Product")]
public class Product
{
[Key]
public int Id { get; set; }
public virtual ICollection<Argument> Arguments { get; set; }//your business
public int AdditionalProductsId { get; set; }
public virtual AdditionalProduct AdditionalProducts { get; set; }
}
Hope to be useful for you! 希望对您有用!
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.