Entity Framework code first database for one to one to many association

Question

我正在使用 entityframework 首先使用代码构建数据库。目的是通过 webservice 调用同步远程数据库。我已经为网络服务调用功能构建了一个结构化实体。

我需要如何对 dB 上下文进行编码才能创建以下关联？

cart.cs通过AssociationsCartAux给出cart_row，如下

public class order
{
    [Key]
    public long? id { get; set; }
    public long? id_cart { get; set; } //which is a foreign key
    public string invoice_number { get; set; }
    ....
}

public class cart
{
    public long? id { get; set; }
    ...
    public AssociationsCartAux associations { get; set; }
}

public class AssociationsCartAux : PrestaShopEntity
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long? id_virtual { get; set; }
    public List<cart_row> cart_rows { get; set; }

    public AssociationsCartAux()
    {
        this.cart_rows = new List<cart_row>();
    }
}

public class cart_row
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long? id_cartRow_fictive { get; set; }
    public long? id_product { get; set; }
    public int quantity { get; set; }
    ....
}

我在我的 dbcontext 文件中尝试了以下代码

    public DbSet<cart> cart { get; set; }
    public DbSet<cart_row> cart_row { get; set; }
    public DbSet<order> order { get; set; }

 protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<AssociationsCartAux>()
        .HasMany(p => p.cart_rows)
        .WithMany().Map(c =>
        {
            c.ToTable("cart_assocation");
        });

当我运行代码时，它正在构建下表

dbo.carts

dbo.cart_row

dbo.AssociationsCartAuxes

id_virtual

dbo.cart_assocation <=== 购物车与 CART_ROW

之间的关联

AssociationsCartAux_id_virtual
cart_row_id_cartRow_fictive

当我重新加载数据同步时 ==> 没问题当我通过订单更新重新加载数据同步时 ==> dbo.AssociationsCartAuxes 尽管更新了当前数据并仅添加了新数据，但现有数据的体积增加了一倍。涉及cart和cart_row之间的linq关联丢失。这让我假设我没有正确构建我的 dbcontext。

我不熟悉 entity framework 所以我尝试了一些方法来做到这一点将 AssociationsCartAux.cs 作为 ComplexType 但由于 cart_row 对象在里面。

提前感谢您的帮助。

有关其他信息，我将如何将数据放入表中

            foreach (cart panier in listcart)
            {
                var result = ctx.cart.SingleOrDefault(b => b.id == panier.id);
                if (result == null)
                {
                    ctx.cart.Add(panier);
                    ctx.SaveChanges();
                }
            }

          foreach (order commande in listorder)
            {
                var result = ctx.order.SingleOrDefault(b => b.id == commande.id);
                if (result == null)
                {
                    ctx.order.Add(commande);
                    ctx.SaveChanges();
                }
            }

Answer 1

一对多关系不需要辅助table，用:

就够了

public class cart
{
    public long? id { get; set; }
    ...
    public List<cart_row> cart_rows { get; set; }
}

而 EF 的魔力将完成剩下的工作，尽管在另一端显式定义关系也是一个好主意：

public class cart_row
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long? id_cartRow_fictive { get; set; }
    public long? id_product { get; set; }
    public int quantity { get; set; }
    ....
    public long? id_cart {get; set;}
    public cart cart {get; set;}
}

并且在 DbContext 中：

protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<cart_row>()
            .HasOne(cr => cr.cart)
            .WithMany(c => c.cart_rows)
            .HasForeignKey(cr => cr.id_cart);
    }

但是还有许多其他方法可以实现此目的，有关更多信息，请查看： https://docs.microsoft.com/en-us/ef/core/modeling/relationships

Answer 2

我找到了答案，也许它可以帮助某人建立这样的三级关联。只需添加： modelBuilder.Entity().ToTable("carts");

到数据库上下文如下。

在数据库上下文中：

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<cart>()
            .HasRequired(s => s.associations)
            .WithRequiredPrincipal(ad => ad.cart);

        modelBuilder.Entity<cart_row>()
            .HasRequired(cr => cr.AssociationsCartAux)
            .WithMany(c => c.cart_rows)
            .HasForeignKey(cr => cr.id_AssocCartAux);

        modelBuilder.Entity<AssociationsCartAux>().ToTable("carts"); <== this solved my issue

Entity Framework code first database for one to one to many association

Entity Framework code first database for one to one to many association

c#

database

entity-framework

entity-framework-6