问题描述
我正在尝试使用代码优先方法在 C# 中创建多对多关系。在现实世界中,一个产品可以有多个类别,一个类别可以有多个产品。所以这就是我想出的:
Product.cs:
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Category> Categories { get; set; }
}
类别.cs:
public class Category
{
public Category(CategoryEnum @enum)
{
Id = (int)@enum;
Name = @enum.ToString();
}
public Category() { }
[Key,DatabaseGenerated(DatabaseGeneratedOption.None)]
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Product> Products { get; set; }
public static implicit operator Category(CategoryEnum @enum) => new Category(@enum);
public static implicit operator CategoryEnum(Category category) => (CategoryEnum)category.Id;
}
Category
映射到一个 Enum
,看起来像:
public enum CategoryEnum
{
Electronics = 1,Gardening = 2
}
最后,DbContext
看起来像这样:
public class ProductDbContext : DbContext
{
public DbSet<Entities.Product> Products { get; set; }
public DbSet<Entities.Category> Categories { get; set; }
public ProductDbContext(DbContextOptions<ProductDbContext> options)
: base(options)
{ }
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
}
}
运行迁移时,我得到以下结果:
将列命名为 CategoriesId
和 ProductsId
有没有办法更改这些列的名称?
解决方法
试试这个:
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder
.Entity<Product>()
.HasMany(p => p.Categories)
.WithMany(p => p.Products)
.UsingEntity<Dictionary<string,object>>("ProductCategory",right => right.HasOne<Category>()
.WithMany()
.HasForeignKey("CategoryId")
.HasConstraintName("FK_ProductCategory_CategoryId__Category_Id")
.OnDelete(DeleteBehavior.Cascade),left => left.HasOne<Product>()
.WithMany()
.HasForeignKey("ProductId")
.HasConstraintName("FK_ProductCategory_ProductId__Product_Id")
.OnDelete(DeleteBehavior.Cascade)
);
}
它有效: