NHibernate单向一对一映射问题
我正在尝试使用 NHibernate 创建单向一对一关系。
示例:客户下达订单。
Customer{ID, Name, Address}
OrderN{ID, Customer, OrderDate}
此处,OrderN.Customer-field 旨在将 Customer.ID 存储为 FK。并且这个字段没有任何唯一的约束。
(OrderN 表被赋予这样的名称以避免 SQL 关键字冲突。)
问题是,执行此 C# 代码后,OrderN.Customer-field 存储空值。
但它应该存储客户的 ID。即1.
如果我在OrderN.hbm.xml中添加
,则会抛出异常:
Could not determine type for: NHibernate__One_To_One__Order_Customer.BO.Customer, NHibernate__One_To_One__Order_Customer.BO, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null, for columns: NHibernate.Mapping.Column(Customer)
如何解决这个问题?
也许这不是一对一的关系。我实际上想了解如何使用
标签。有人可以在这方面帮助我吗?
Customer.sql
CREATE TABLE [dbo].[Customer](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Name] [varchar](50) NULL,
[Address] [varchar](50) NULL,
CONSTRAINT [PK_Customer] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
Customer.cs
public class Customer
{
private int _id;
public virtual int ID
{
get { return _id; }
set { _id = value; }
}
private string _name;
public virtual string Name
{
get { return _name; }
set { _name = value; }
}
private string _address;
public virtual string Address
{
get { return _address; }
set { _address = value; }
}
}
Customer.hbm.xml
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping
xmlns="urn:nhibernate-mapping-2.2"
>
<class name="NHibernate__One_To_One__Order_Customer.BO.Customer, NHibernate__One_To_One__Order_Customer.BO" table="Customer">
<id name="ID" >
<generator class="native" />
</id>
<property name="Name" column="Name" />
<property name="Address" column="Address" />
</class>
</hibernate-mapping>
OrderN.sql
CREATE TABLE [dbo].[OrderN](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Customer] [int] NULL,
[OrderDate] [datetime] NULL,
CONSTRAINT [PK_Order] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[OrderN] WITH CHECK ADD CONSTRAINT [FK_Order_Customer] FOREIGN KEY([Customer])
REFERENCES [dbo].[Customer] ([ID])
GO
ALTER TABLE [dbo].[OrderN] CHECK CONSTRAINT [FK_Order_Customer]
OrderN.cs
public class OrderN
{
private int _id;
public virtual int ID
{
get { return _id; }
set { _id = value; }
}
private Customer _customer;
public virtual Customer Customer
{
get { return _customer; }
set { _customer = value; }
}
private DateTime _orderDate;
public virtual DateTime OrderDate
{
get { return _orderDate; }
set { _orderDate = value; }
}
}
OrderN.hbm.xml
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping
xmlns="urn:nhibernate-mapping-2.2"
>
<class name="NHibernate__One_To_One__Order_Customer.BO.OrderN, NHibernate__One_To_One__Order_Customer.BO" table="OrderN">
<id name="ID">
<generator class="native" />
</id>
<property name="OrderDate" column="OrderDate"/>
<one-to-one
name="Customer"
class="NHibernate__One_To_One__Order_Customer.BO.Customer, NHibernate__One_To_One__Order_Customer.BO" />
</class>
</hibernate-mapping>
主程序
OrderN o = new OrderN();
o.OrderDate = DateTime.Now;
o.Customer = new Repository<Customer>().Get<Customer>(1);
Repository<OrderN> rep = new Repository<OrderN>();
rep.Save(o);
I am trying to create a Unidirectional one-to-one relationship using NHibernate.
Example: An Order is given by a Customer.
Customer{ID, Name, Address}
OrderN{ID, Customer, OrderDate}
Here, OrderN.Customer-field is intended to store Customer.ID as an FK. And this field doesn't have any unique constraint.
(The OrderN-table is given such a name to avoid SQL keyword conflict.)
The problem is, After executing this c# code, OrderN.Customer-field is storing a null value.
But it was supposed to store the ID of the Customer. I.e. 1.
And if I add <property name="Customer" column="Customer" />
in OrderN.hbm.xml, an exception is thrown:
Could not determine type for: NHibernate__One_To_One__Order_Customer.BO.Customer, NHibernate__One_To_One__Order_Customer.BO, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null, for columns: NHibernate.Mapping.Column(Customer)
How to solve this problem?
May be it is not a one-to-one relationship. I am actually trying to understand how is the <one-to-one />
tag used. Can anyone please help me in this regard?
Customer.sql
CREATE TABLE [dbo].[Customer](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Name] [varchar](50) NULL,
[Address] [varchar](50) NULL,
CONSTRAINT [PK_Customer] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
Customer.cs
public class Customer
{
private int _id;
public virtual int ID
{
get { return _id; }
set { _id = value; }
}
private string _name;
public virtual string Name
{
get { return _name; }
set { _name = value; }
}
private string _address;
public virtual string Address
{
get { return _address; }
set { _address = value; }
}
}
Customer.hbm.xml
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping
xmlns="urn:nhibernate-mapping-2.2"
>
<class name="NHibernate__One_To_One__Order_Customer.BO.Customer, NHibernate__One_To_One__Order_Customer.BO" table="Customer">
<id name="ID" >
<generator class="native" />
</id>
<property name="Name" column="Name" />
<property name="Address" column="Address" />
</class>
</hibernate-mapping>
OrderN.sql
CREATE TABLE [dbo].[OrderN](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Customer] [int] NULL,
[OrderDate] [datetime] NULL,
CONSTRAINT [PK_Order] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[OrderN] WITH CHECK ADD CONSTRAINT [FK_Order_Customer] FOREIGN KEY([Customer])
REFERENCES [dbo].[Customer] ([ID])
GO
ALTER TABLE [dbo].[OrderN] CHECK CONSTRAINT [FK_Order_Customer]
OrderN.cs
public class OrderN
{
private int _id;
public virtual int ID
{
get { return _id; }
set { _id = value; }
}
private Customer _customer;
public virtual Customer Customer
{
get { return _customer; }
set { _customer = value; }
}
private DateTime _orderDate;
public virtual DateTime OrderDate
{
get { return _orderDate; }
set { _orderDate = value; }
}
}
OrderN.hbm.xml
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping
xmlns="urn:nhibernate-mapping-2.2"
>
<class name="NHibernate__One_To_One__Order_Customer.BO.OrderN, NHibernate__One_To_One__Order_Customer.BO" table="OrderN">
<id name="ID">
<generator class="native" />
</id>
<property name="OrderDate" column="OrderDate"/>
<one-to-one
name="Customer"
class="NHibernate__One_To_One__Order_Customer.BO.Customer, NHibernate__One_To_One__Order_Customer.BO" />
</class>
</hibernate-mapping>
Main-program
OrderN o = new OrderN();
o.OrderDate = DateTime.Now;
o.Customer = new Repository<Customer>().Get<Customer>(1);
Repository<OrderN> rep = new Repository<OrderN>();
rep.Save(o);
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那么一个客户只能有一个订单吗?我希望这是一个大的!
这不是一对一的关系,而是一对多的关系。客户是一侧,订单是多方(客户有订单)。尝试像这样映射它:
So a Customer can only ever have one Order? I hope it's a big one!
This isn't a one-to-one relationship, it's one-to-many. Customer is the one side, and Order is the many (Customer has Orders). Try mapping it like this: