问题
I have this product class which has a list of products associated.
eg:
Product = StarWar
AssociatedProducts = Episode V: The Empire Strikes Back, Episode VI: Return of the Jedi, Episode VII: The Force Awakens
But EF generates the database with some extra columns.
This is my Product Class:
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public string ShortDescription { get; set; }
public string FullDescription { get; set; }
public decimal UnitPrice { get; set; }
......
public virtual ICollection<AssociatedProducts> AssociatedProducts { get; set; }
......
}
This is my AssociatedProduct Class:
public class AssociatedProducts
{
public int Id { get; set; }
public int ProductId { get; set; }
public int AssociatedProductId { get; set; }
public int DisplayOrder { get; set; }
public DateTime CreatedOn { get; set; }
public virtual Product Products { get; set; }
public virtual Product AssociatedProductsId { get; set; }
}
This is my mapping for AssocietedProduct class:
public AssociatedProductsMap()
{
// Primary Key
HasKey(a => a.Id);
// Properties
Property(a => a.CreatedOn).IsRequired();
Property(a => a.ProductId).IsRequired();
Property(a => a.AssociatedProductId).IsRequired();
Property(a => a.DisplayOrder).IsRequired();
//Relationship
HasRequired(a => a.Products)
.WithMany(p => p.Products)
.HasForeignKey(a => a.ProductId)
.WillCascadeOnDelete(false);
HasRequired(a => a.AssociatedProductsId)
.WithMany(p => p.AssociatedProducts)
.HasForeignKey(a => a.AssociatedProductId)
.WillCascadeOnDelete(false);
//Table
ToTable("AssociatedProducts");
}
And this is how I am seeding:
var associetedProducts = new List<AssociatedProducts>
{
new AssociatedProducts {ProductId= 1, AssociatedProductId = 3, DisplayOrder = 1, CreatedOn = DateTime.Now},
new AssociatedProducts {ProductId= 1, AssociatedProductId = 4, DisplayOrder = 2, CreatedOn = DateTime.Now},
new AssociatedProducts {ProductId= 1, AssociatedProductId = 5, DisplayOrder = 3, CreatedOn = DateTime.Now}
}
new List<Product>
{
new Product {Name = "StarWar", ShortDescription = "...", FullDescription = "P.......", UnitPrice = 15m, AssociatedProducts = associetedProducts},
new Product {Name = "StarWar Episode V", ShortDescription = "...", FullDescription = "P.......", UnitPrice = 15m},
new Product {Name = "StarWar Episode VI", ShortDescription = "...", FullDescription = "P.......", UnitPrice = 15m},
new Product {Name = "StarWar Episode VII", ShortDescription = "...", FullDescription = "P.......", UnitPrice = 15m},
}.ForEach(a => context.Products.AddOrUpdate(a));
context.SaveChanges();
This is what I expect from AssociatedProductsId Table: ID + ProductId (FK) + AssociatedProductsId(FK) + date + ......
But this is what I get:
What is my mistake ? Is this a good way to associate a product ?
回答1:
I think your classes are not right.
1 Problem: Why EF generates the table with extra columns?
In that case EF is using TPH strategy. Take a look at this link http://blogs.msdn.com/b/alexj/archive/2009/04/15/tip-12-choosing-an-inheritance-strategy.aspx
2 Problem: What is my mistake ? Is this a good way to associate a product ?
Your mapping should be something like this:
public class Product
{
public int ProductId { get; set; }
public string Name { get; set; }
public virtual ICollection<ProductAssociation> AssociatedProducts { get; set; }
public virtual ICollection<ProductAssociation> ProductsAssociatedThisProduct { get; set; }
}
public class ProductAssociation
{
public int ProductId { get; set; }
public int ProductAssociatedId { get; set; }
public DateTime CreationDate { get; set; }
public virtual Product Product { get; set; }
public virtual Product ProductAssociated { get; set; }
}
public class Context : DbContext
{
public Context() : base("Model2")
{
}
public DbSet<Product> Products { get; set; }
public DbSet<ProductAssociation> ProductsAssociations { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Product>()
.HasKey(i => i.ProductId);
modelBuilder.Entity<ProductAssociation>()
.HasKey(i => new {i.ProductId, i.ProductAssociatedId });
modelBuilder.Entity<Product>()
.HasMany(i => i.AssociatedProducts)
.WithRequired(i => i.ProductAssociated)
.HasForeignKey(i => i.ProductAssociatedId)
.WillCascadeOnDelete(false);
modelBuilder.Entity<Product>()
.HasMany(i => i.ProductsAssociatedThisProduct)
.WithRequired(i => i.Product)
.HasForeignKey(i => i.ProductId)
.WillCascadeOnDelete(false);
base.OnModelCreating(modelBuilder);
}
}
Seed
var product1 = new Product() { Name = "StarWars", ProductId = 1 };
var product2 = new Product() { Name = "StarWars II", ProductId = 2 };
context.ProductsAssociations.AddOrUpdate(new ProductAssociation { Product = product1, CreationDate = DateTime.Now, ProductAssociated = product2 });
context.Products.AddOrUpdate(product1);
context.Products.AddOrUpdate(product2);
context.SaveChanges();
来源:https://stackoverflow.com/questions/31461173/entity-framework-fluent-api-create-table-with-2-fk