Nhibernate创建具有对象属性的对象

Question

我刚刚开始使用NHibernate。我有两个对象：

public class Supplier 
{
    public virtual int id{get;set;}
    public virtual SupplierAddress address{get;set;}
    public virtual string Name{get;set;}
}
public class SupplierAddress 
{
    public virtual int id{get;set;}
    public virtual Supplier{get;set;}
    public virtual string SupplierAddressLine{get;set;}
}

当我想创建一个新的Supplier时，我创建了一个新对象：

var supplierAddress = new SupplierAddress {
    SupplierAddressLine = "someLine"
}

var supplier = new Supplier 
{
    Name = "someName",
    SupplierAddress = SupplierAddressLine 
}

然后，当我尝试使用保存时：

_session.Save(supplier);

我收到错误：“无法将值NULL插入列'id'

更新1映射

for SupplierAddress

---

        Id(x => x.Id).GeneratedBy.Identity().Column("Id");
        References(x => x.Supplier).Column("SupplierId");
        Map(x => x.AddressLine1).Column("AddressLine1").Not.Nullable().Length(255);

供应商

---

        Id(x => x.Id).GeneratedBy.Identity().Column("Id");
        References(x => x.SupplierAddress).Column("SupplierAddressId").Not.Nullable();
        HasMany(x => x.SupplierAddresses).KeyColumn("SupplierId");

Answer 1

您应该在Supplier→SupplierAddress关系中设置一些cascade rules：

References(s => s.SupplierAddress)
    .Column("SupplierAddressId")
    .Not.Nullable()
    .Cascade.All(); /* Cascade operations that happen on `Supplier` */

否则，NHibernate不知道保存父（Supplier）也应该保存孩子（SupplierAddress）

修改：我认为您实际上在这里错误地使用了References。

在映射中，当你说另一个实体References时，你基本上告诉NHibernate 这段关系的另一面是HasMany

在您的情况下，Supplier和SupplierAddress实际上分别没有SupplierAddress个或Supplier个。

考虑到这一点，你可能意味着两件事之一：

1. 多个SupplierAddress共享Suppliers。这意味着SupplierAddress实际上有很多 Suppliers，但Supplier只有一个SupplierAddress。

   在C＃类中，这意味着SupplierAddress的集合为Suppliers（或者根本没有引用Supplier。

   在这种情况下，您的数据库表将如下所示：

   create table [SupplierAddress]
   (
       [Id] int identity(1,1) primary key clustered,
       [AddressLine1] nvarchar(255) not null
   );
   create table [Supplier]
   (
       [Id] int identity(1,1) primary key clustered,
       [SupplierAddressId] int not null references [SupplierAddress]([Id])
   )
   

   您的C＃类看起来像这样：

   public class Supplier
   {   
       public virtual int Id { get; set; }
   
       public virtual SupplierAddress SupplierAddress { get; set; }
   
       public virtual string Name { get; set; }
   }
   
   public class SupplierAddress
   {
       public virtual int Id { get; set; }
   
       public virtual string AddressLine1 { get; set; }
   }
   

   你的映射看起来像这样：

   public class SupplierMap : ClassMap<Supplier>
   {
       public SupplierMap()
       {
           Id(s => s.Id).GeneratedBy.Identity().Column("Id");
           References(s => s.SupplierAddress)
               .Column("SupplierAddressId")
               .Cascade.All();
       }
   }
   
   public class SupplierAddressMap : ClassMap<SupplierAddress>
   {
       public SupplierAddressMap()
       {
           Id(s => s.Id).GeneratedBy.Identity().Column("Id");
   
           Map(s => s.AddressLine1)
               .Column("AddressLine1")
               .Not.Nullable()
               .Length(255);
       }
   }
   

2. Supplier只有一个SupplierAddress，SupplierAddress只与一个Supplier相关联。另一种思考方式是整个SupplierAddress表可以在逻辑上合并到Supplier。

   在这种情况下，您的数据库表将如下所示：

   create table [SupplierAddress]
   (
       [Id] int identity(1,1) primary key clustered,
       [AddressLine1] nvarchar(255) not null,
       [SupplierId]  int not null
   );
   
   create table [Supplier]
   (
       [Id] int identity(1,1) primary key clustered,
       [SupplierAddressId] int references [SupplierAddress]([Id])
   );
   
   
   alter table [SupplierAddress] 
       add constraint [FK_SupplierAddress_Supplier] 
       foreign key ([SupplierId]) references [Supplier]([Id])
   

   您的C＃类看起来像这样：

   public class Supplier
   {   
       private SupplierAddress supplierAddress;
   
       public virtual int Id { get; set; }
   
       public virtual SupplierAddress SupplierAddress 
       {
           get { return this.supplierAddress; }
           set 
           { 
               this.supplierAddress = value;
               this.supplierAddress.Supplier = this;
           }
       }
   
       public virtual string Name { get; set; }
   }
   
   public class SupplierAddress
   {
       public virtual int Id { get; set; }
   
       public virtual string AddressLine1 { get; set; }
   
       public virtual Supplier Supplier { get; set; }
   }
   

   你的映射看起来像这样：

   public class SupplierMap : ClassMap<Supplier>
   {
       public SupplierMap()
       {
           Id(s => s.Id).GeneratedBy.Identity().Column("Id");
           HasOne(s => s.SupplierAddress).PropertyRef(s => s.Supplier)
               .Access.CamelCaseField()
               .Cascade.All();
       }
   }
   
   public class SupplierAddressMap : ClassMap<SupplierAddress>
   {
       public SupplierAddressMap()
       {
           Id(s => s.Id).GeneratedBy.Identity().Column("Id");
           Map(s => s.AddressLine1).Column("AddressLine1");
           References(s => s.Supplier).Column("SupplierId").Unique();
       }
   }
   

   请注意，当Supplier.SupplierAddress为set时，地址的Supplier属性已设置。