EF Code First creating obsolete column?

Question

I have the following classes that I use for my database:

public abstract class BaseProduct
{
    public int ID { get; set; }

    [Required, StringLength(100), Display(Name = "Name")]
    public string ProductName { get; set; }

    [Required, StringLength(10000), Display(Name = "Product Description"), DataType(DataType.MultilineText)]
    public string Description { get; set; }

    public string ImagePath { get; set; }

    [Display(Name = "Price")]
    public double? UnitPrice { get; set; }

    public int? CategoryID { get; set; }

    public virtual Category Category { get; set; }

    public string Author { get; set; }

    public virtual ICollection<PriceRelation> Prices { get; set; }
}
[Table("Packages")]
public class Package : BaseProduct
{
    public virtual ICollection<Product> Products { get; set; }
}
[Table("Products")]
public class Product : BaseProduct
{
    public virtual ICollection<Package> Packages { get; set; }
}
public class Category
{
    [ScaffoldColumn(false)]
    public int CategoryId { get; set; }

    [Required, StringLength(100), Display(Name = "Name")]
    public string CategoryName { get; set; }

    [Display(Name = "Category Description")]
    public string Description { get; set; }

    public int? ParentID { get; set; }
    [ForeignKey("ParentID")]
    public virtual Category Parent { get; set; }

    public virtual ICollection<Category> Children { get; set; } 

    public virtual ICollection<Product> Products { get; set; }

}

And this is the model builder:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Package>().HasMany(p => p.Products).WithMany(p => p.Packages)
            .Map(m =>
                {
                    m.ToTable("PackageRelations");
                    m.MapLeftKey("PackageID");
                    m.MapRightKey("ProductID");
                });
    }
    }

It sets up the relations as I want to, in the following way:

Table: BaseProducts Columns: ID, ProductName, Description, ImagePath, UnitPrice, CategoryID, Author

Table: Packages Columns: ID

Table: Products Columns: ID, Category_CategoryID

The thing I'm wondering is, why does it create the column Category_CategoryID in the products table? When I populate the table, all the values in this column are null, so it doesn't look like it's being used for anything.

Also, it doesn't seem to have the relations right - because the virtual collection of Products on the category is always empty.

Answer 1

您可能需要将CategoryID重命名为CategoryId，以便EF可以将其识别为Category实体的关键字段。

Answer 2

I figured it out! The virtual ICollection in the category was of the type Product, when in fact it should be BaseProduct.

It makes sense that the Product would get an extra column to reference the Category when it has that reference for only that type.