NHibernate的关联映射(one-to-one,one-to-many,many-to-many)以及cascade分析
2007-08-22 15:25
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NHibernate的关联映射(one-to-one,one-to-many,many-to-many)以及cascade分析
一、典型设置
cascade：（默认为none）级联。指明哪些操作会从对象级联到关联的对象。
inverse： (默认为false) 标记这个集合作为双向关联关系中的方向一端。在双向关联时才需要设置。在设为false的一端对cascade进行维护。处于性能的考虑，一般在数据少的一端或者被依赖端设置inverse="true",而让数据多的一段维护cascade。
1.one-to-one
1.1 数据库表结构
其中T_Person为主表，T_Employee为子表。T_Employee的PersonId参照T_Peson的PersonId。
1.2 示例映射类文件
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Person
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _personid;
private string _name;
private Employee _employee;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Person()
{
_personid = 0;
_name = null;
_employee = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int PersonId
{
get
{ return _personid; }
set
{
_isChanged |= (_personid != value);
_personid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public Employee Employee
{
get
{ return _employee; }
set
{ _employee = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Person castObj = (Person) obj;
return (castObj != null) &&
(_personid == castObj.PersonId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_personid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Employee
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _personid;
private string _job;
private Person _person;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Employee()
{
_personid = 0;
_job = null;
_person = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int PersonId
{
get
{ return _personid; }
set
{
_isChanged |= (_personid != value);
_personid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Job
{
get
{ return _job; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Job", value, value.ToString());
_isChanged |= (_job != value);
_job = value;
}
}
public Person Person
{
get
{ return _person; }
set
{ _person = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Employee castObj = (Employee) obj;
return (castObj != null) &&
(_personid == castObj.PersonId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_personid.GetHashCode();
return hash;
}
#endregion
}
}
1.3 示例映射文件
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne.Person,DDLLY.TestNHibernate.TestAssociation" table="T_Person">
<id name="PersonId" column="PersonId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<one-to-one name="Employee" class="DDLLY.TestNHibernate.TestAssociation.OneToOne.Employee,DDLLY.TestNHibernate.TestAssociation" cascade="all"></one-to-one>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne.Employee,DDLLY.TestNHibernate.TestAssociation" table="T_Employee">
<id name="PersonId" column="PersonId" type="Int32" unsaved-value="0">
<generator class="foreign">
<param name="property">Person</param>
</generator>
</id>
<property column="Job" type="String" name="Job" length="64" />
<one-to-one name="Person" class="DDLLY.TestNHibernate.TestAssociation.OneToOne.Person,DDLLY.TestNHibernate.TestAssociation" constrained="true"></one-to-one>
</class>
</hibernate-mapping>
1.4 说明
constrained（约束）: 表明该类对应的表对应的数据库表，和被关联的对象所对应的数据库表之间，通过一个外键引用对主键进行约束。这个选项影响Save()和Delete()在级联执行时的先后顺序（也在schema export tool中被使用）。
property-ref: (可选) 指定关联类的一个属性，这个属性将会和本外键相对应。如果没有指定，会使用对方关联类的主键。
<generator class="foreign">:表示使用另外一个相关联的对象的标识符，来创建主健。T_Employee的PersonId来自T_Person的ParentId。
Employee依赖于Person,所以通常在Person设置cascade。
2.另一种one-to-one
2.1数据库表结构
其中T_Person1为主表，T_Employee1为子表。T_Employee1的PersonId设置唯一约束，参照T_Person1的PersonId。
2.2示例映射类文件
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Person
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _personid;
private string _name;
private Employee _employee;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Person()
{
_personid = 0;
_name = null;
_employee = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int PersonId
{
get
{ return _personid; }
set
{
_isChanged |= (_personid != value);
_personid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public Employee Employee
{
get
{ return _employee; }
set
{ _employee = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Person castObj = (Person) obj;
return (castObj != null) &&
(_personid == castObj.PersonId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_personid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Employee
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _employeeId;
private string _job;
private Person _person;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Employee()
{
_employeeId = 0;
_job = null;
_person = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int EmployeeId
{
get
{ return _employeeId; }
set
{
_isChanged |= (_employeeId != value);
_employeeId = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Job
{
get
{ return _job; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Job", value, value.ToString());
_isChanged |= (_job != value);
_job = value;
}
}
public Person Person
{
get
{ return _person; }
set
{ _person = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Employee castObj = (Employee) obj;
return (castObj != null) &&
(_employeeId == castObj.EmployeeId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_employeeId.GetHashCode();
return hash;
}
#endregion
}
}
2.3示例映射文件
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Person,DDLLY.TestNHibernate.TestAssociation" table="T_Person1">
<id name="PersonId" column="PersonId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<one-to-one name="Employee" class="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Employee,DDLLY.TestNHibernate.TestAssociation" cascade="all"></one-to-one>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Employee,DDLLY.TestNHibernate.TestAssociation" table="T_Employee1">
<id name="EmployeeId" column="EmployeeId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Job" type="String" name="Job" length="64" />
<many-to-one name="Person" class="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Person,DDLLY.TestNHibernate.TestAssociation" column="PersonId" unique="true"></many-to-one>
</class>
</hibernate-mapping>
2.4说明
这种one-to-one实际上是一种特殊的one-to-many,如果T_Employee1的PersonId不设置唯一约束，则可成为one-to-many。所以在T_Employee端设置many-to-one而不是one-to-one,记住要加上unique="true"表示唯一约束。
3.one-to-many
3.1 数据库表结构
T_Parent为主表，T_Child的ParentId参照T_Parent的ParentId。
注意:对于单向的one-to-many映射,cascade过程中会用到把T_Child表的ParentId设置为Null,所以ParentId应设为允许NULL;
而双向one-to-many映射,建议把T_Child的ParentI设置为不允许NULL
3.2 示例映射类文件(单向)
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Parent
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _parentid;
private string _name;
private IList _children;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Parent()
{
_parentid = 0;
_name = null;
_children = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ParentId
{
get
{ return _parentid; }
set
{
_isChanged |= (_parentid != value);
_parentid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual IList Children
{
get
{ return _children; }
set
{
_isChanged |= (_children != value);
_children = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Parent castObj = (Parent) obj;
return (castObj != null) &&
(_parentid == castObj.ParentId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_parentid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Child
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _childid;
private string _name;
private int _parentid;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Child()
{
_childid = 0;
_name = null;
_parentid = 0;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ChildId
{
get
{ return _childid; }
set
{
_isChanged |= (_childid != value);
_childid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual int ParentId
{
get
{ return _parentid; }
set
{
_isChanged |= (_parentid != value);
_parentid = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Child castObj = (Child) obj;
return (castObj != null) &&
(_childid == castObj.ChildId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_childid.GetHashCode();
return hash;
}
#endregion
}
}
3.3 示例映射文件（单向）
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany1.Parent,DDLLY.TestNHibernate.TestAssociation" table="T_Parent">
<id name="ParentId" column="ParentId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<bag name="Children" cascade="all" lazy="true">
<key column="ParentId"/>
<one-to-many class="DDLLY.TestNHibernate.TestAssociation.OneToMany1.Child,DDLLY.TestNHibernate.TestAssociation"/>
</bag>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany1.Child,DDLLY.TestNHibernate.TestAssociation" table="T_Child">
<id name="ChildId" column="ChildId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<property column="ParentId" type="Int32" name="ParentId"/>
</class>
</hibernate-mapping>
3.4 示例映射类文件(双向)
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Parent
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _parentid;
private string _name;
private IList _children;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Parent()
{
_parentid = 0;
_name = null;
_children = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ParentId
{
get
{ return _parentid; }
set
{
_isChanged |= (_parentid != value);
_parentid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual IList Children
{
get
{ return _children; }
set
{
_isChanged |= (_children != value);
_children = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Parent castObj = (Parent) obj;
return (castObj != null) &&
(_parentid == castObj.ParentId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_parentid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Child
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _childid;
private string _name;
private Parent _parent;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Child()
{
_childid = 0;
_name = null;
_parent = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ChildId
{
get
{ return _childid; }
set
{
_isChanged |= (_childid != value);
_childid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual Parent Parent
{
get
{ return _parent; }
set
{
_isChanged |= (_parent != value);
_parent = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Child castObj = (Child) obj;
return (castObj != null) &&
(_childid == castObj.ChildId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_childid.GetHashCode();
return hash;
}
#endregion
}
}
3.5 示例映射类文件(双向)
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany.Parent,DDLLY.TestNHibernate.TestAssociation" table="T_Parent">
<id name="ParentId" column="ParentId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<bag name="Children" cascade="all" inverse="true" lazy="true">
<key column="ParentId"/>
<one-to-many class="DDLLY.TestNHibernate.TestAssociation.OneToMany.Child,DDLLY.TestNHibernate.TestAssociation"/>
</bag>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany.Child,DDLLY.TestNHibernate.TestAssociation" table="T_Child">
<id name="ChildId" column="ChildId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<many-to-one name="Parent" column="ParentId" class="DDLLY.TestNHibernate.TestAssociation.OneToMany.Parent,DDLLY.TestNHibernate.TestAssociation" />
</class>
</hibernate-mapping>
3.6 说明
在NHibernate配置文件中使用<set>, <list>, <map>, <bag>, <array> 和 <primitive-array>等元素来定义集合。<bag>是典型的一个，代码中我们用IList和它对应。我们以后会详细讲集合这个话题。
lazy表示允许延迟加载。表示在需要使用时才加载需要的数据。例如使用lazy时我们Load一个Parent他的Children为空，只有我们访问它的某一个Child时数据才会被加载；而不设置lazy我们Load一个Parent时其Children将同时加载。注意：使用lazy加载必须保证对应ISession的打开，否则懒加载会失败。
one-to-many可以设置单向和双向映射，设置单向时Child一段不设置many-to-one，而设置了ParentId的属性。
双向映射需要设置inverse而单向不需要。
单项映射在cascade时会对把T_Child的ParentId使用Update为Null的操作。
建议尽量使用双向映射。
4.many-to-many
4.1 数据库表结构
4.2 示例映射类文件
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.ManyToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class User
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _userid;
private string _username;
private string _password;
private string _email;
private IList _roles;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public User()
{
_userid = 0;
_username = null;
_password = null;
_email = null;
_roles = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int UserId
{
get
{ return _userid; }
set
{
_isChanged |= (_userid != value);
_userid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string UserName
{
get
{ return _username; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for UserName", value, value.ToString());
_isChanged |= (_username != value);
_username = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Password
{
get
{ return _password; }
set
{
if (value != null)
if (value.Length > 32)
throw new ArgumentOutOfRangeException("Invalid value for Password", value, value.ToString());
_isChanged |= (_password != value);
_password = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Email
{
get
{ return _email; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Email", value, value.ToString());
_isChanged |= (_email != value);
_email = value;
}
}
public IList Roles
{
get
{ return _roles; }
set
{ _roles = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
User castObj = (User) obj;
return (castObj != null) &&
(_userid == castObj.UserId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_userid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.ManyToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Role
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _roleid;
private string _rolename;
private IList _users;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Role()
{
_roleid = 0;
_rolename = null;
_users = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int RoleId
{
get
{ return _roleid; }
set
{
_isChanged |= (_roleid != value);
_roleid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string RoleName
{
get
{ return _rolename; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for RoleName", value, value.ToString());
_isChanged |= (_rolename != value);
_rolename = value;
}
}
public IList Users
{
get
{ return _users; }
set
{ _users = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Role castObj = (Role) obj;
return (castObj != null) &&
(_roleid == castObj.RoleId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_roleid.GetHashCode();
return hash;
}
#endregion
}
}
4.3 示例映射文件
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.ManyToMany.User,DDLLY.TestNHibernate.TestAssociation" table="T_User">
<id name="UserId" column="UserId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="UserName" type="String" name="UserName" not-null="true" length="64" />
<property column="Password" type="String" name="Password" not-null="true" length="32" />
<property column="Email" type="String" name="Email" length="64" />
<bag name="Roles" table="T_User_Role" lazy="true">
<key column="UserId"/>
<many-to-many class="DDLLY.TestNHibernate.TestAssociation.ManyToMany.Role,DDLLY.TestNHibernate.TestAssociation" column="RoleId"/>
</bag>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.ManyToMany.Role,DDLLY.TestNHibernate.TestAssociation" table="T_Role">
<id name="RoleId" column="RoleId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="RoleName" type="String" name="RoleName" not-null="true" length="64" />
<bag name="Users" table="T_User_Role" lazy="true" inverse="true">
<key column="RoleId"/>
<many-to-many class="DDLLY.TestNHibernate.TestAssociation.ManyToMany.User,DDLLY.TestNHibernate.TestAssociation" column="UserId"/>
</bag>
</class>
</hibernate-mapping>
4.4 说明
many-to-many性能不佳，数据量大时应尽可能避免使用。并尽可能使用lazy="true"。
在数据量少的一端设置inverse="true"，让数据量多的一段维护cascade。
二、cascade分析
1.总述
cascade：（默认为none）级联。指明哪些操作会从对象级联到关联的对象。
orphans：孤儿,没有夫对象的子对象。对于代码Child.Parent==null,对于数据库T_Child表中ParentId为Null的数据。
delete orphans表示cascade时删除孤儿。
一般系统中是不允许孤儿存在的，我们可以通过数据库的约束来限制孤儿，例如T_Child的ParentId设为Not NULL。
如果确实存在孤儿请考虑适合的cascade策略。
2.one-to-one
a.初始化数据
b.测试方法
TestAddPersonWithAddEmployee
Person person = new Person();
person.Name = "newPerson";
Employee employee = new Employee();
employee.Job = "newJob";
person.Employee = employee;
employee.Person = person;
session.Save(person);
TestUpdatePersonWithAddEmployee
Person person = session.Load(typeof (Person), 2) as Person;
person.Employee = new Employee();
person.Employee.Person = person;
person.Employee.Job = "LLYJob";
session.Update(person);
TestUpdatePersonWithUpdateEmployee
Person person = session.Load(typeof (Person), 1) as Person;
person.Employee.Job = "DDL'New Job";
session.Update(person);
TestDeletePersonWithDeleteEmployee
Person person = session.Load(typeof (Person), 1) as Person;
session.Delete(person);
c.测试结果
2.另一种one-to-one
a.初始化数据
b.测试方法
TestAddPersonWithAddEmployee
不支持
TestUpdatePersonWithAddEmployee
Person person = session.Load(typeof (Person), 2) as Person;
person.Employee = new Employee();
person.Employee.Person = person;
person.Employee.Job = "LLYJob";
session.Update(person);
session.Flush();
TestUpdatePersonWithUpdateEmployee
Person person = session.Load(typeof (Person), 1) as Person;
person.Employee.Job = "DDL'New Job";
session.Update(person);
session.Flush();
TestDeletePersonWithDeleteEmployee
Person person = session.Load(typeof (Person), 1) as Person;
session.Delete(person);
session.Flush();
c.测试结果
3.one-to-many(双向)
a.初始化数据
b.测试方法
TestAddParentWithAddChild
Parent parent = new Parent();
parent.Name = "NewParent";
Child child = new Child();
child.Name = "NewChild";
child.Parent = parent;
parent.Children.Add(child);
session.Save(parent);
session.Flush();
TestUpdateParentWithAddChild
Parent parent = session.Load(typeof (Parent), 2) as Parent;
Child child = new Child();
child.Name = "NewChild";
child.Parent = parent;
parent.Children.Add(child);
session.Update(parent);
session.Flush();
TestUpdateParentWithUpdateChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
Child child = (Child) parent.Children[0];
child.Name = "UpdateName";
session.Update(parent);
session.Flush();
TestDeleteParentWithChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
session.Delete(parent);
session.Flush();
c.测试结果
4.one-to-many(单向)
a.初始化数据
同上
b.测试方法
TestAddParentWithAddChild
不支持
TestUpdateParentWithAddChild
Parent parent = session.Load(typeof (Parent), 2) as Parent;
Child child = new Child();
child.Name = "NewChild";
child.ParentId = parent.ParentId;
parent.Children.Add(child);
session.Update(parent);
session.Flush();
TestUpdateParentWithUpdateChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
Child child = (Child) parent.Children[0];
child.Name = "UpdateName";
session.Update(parent);
session.Flush();
TestDeleteParentWithChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
session.Delete(parent);
session.Flush();
c.测试结果
5.many-to-many
many-to-many和别的关联映射有所不同。例子中：Role和User没有直接的依赖关系，而是通过一张中间表完成。在删除User时一般不会要求删除Role，而是删除之间的关系（即从中间表删除数据）。
a.初始化数据
b.测试方法
TestAddRoleToUser
User user = session.Load(typeof (User), 1) as User;
Role role = session.Load(typeof (Role), 3) as Role;
user.Roles.Add(role);
role.Users.Add(user);
session.Update(user);
session.Flush();
TestRemoveRoleFromUser
User user = session.Load(typeof (User), 1) as User;
Role role = session.Load(typeof (Role), 2) as Role;
user.Roles.Remove(role);
role.Users.Remove(user);
session.Update(user);
session.Flush();
TestUpdateUserWithRole
User user = session.Load(typeof(User), 2) as User;
((Role) user.Roles[0]).RoleName = "UpdateRole";
session.Update(user);
session.Flush();
TestDeleteUserWithSetRole
User user = session.Load(typeof (User), 1) as User;
session.Delete(user);
session.Flush();
c.测试结果
三、结论
关联是NHibernate里面功能很强的一块，但也使很容易滥用而造成引起性能或其他问题的地方。所以请慎重的使用。
在使用之前，请考虑好以下问题：
1.关系分析，一对多，多对多，还是一对一。
2.确定依赖关系，例如：Child依赖于Parent。
3.是否允许存在孤儿，例如：存在Child没有Parent（即在数据库中ParentId为Null的Child）。
4.在对等的关系中是否有主动端。例如：需要给Parent设置Child还是给Child找Parent，或者两边都可以操作。
5.关联两端可能出现的数据量以及在页面显示时是否分页。如果数据量大或者页面上需要分页显示，建议不要采用关联映射。如果数据量大，性能会不好，如果需要分页，关联所有数据似乎没有什么意思。
6.页面上可能的对象操作方法。例如：先读取一个Parent，然后添加Child，然后保存。
请根据你的情况设置关联映射，而对于cascade标准的设置可以满足绝大多数的需要，如一有特殊情况，请按照上面的分析选择合适的。
下载代码
一、典型设置
cascade：（默认为none）级联。指明哪些操作会从对象级联到关联的对象。
inverse： (默认为false) 标记这个集合作为双向关联关系中的方向一端。在双向关联时才需要设置。在设为false的一端对cascade进行维护。处于性能的考虑，一般在数据少的一端或者被依赖端设置inverse="true",而让数据多的一段维护cascade。
1.one-to-one
1.1 数据库表结构
其中T_Person为主表，T_Employee为子表。T_Employee的PersonId参照T_Peson的PersonId。
1.2 示例映射类文件
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Person
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _personid;
private string _name;
private Employee _employee;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Person()
{
_personid = 0;
_name = null;
_employee = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int PersonId
{
get
{ return _personid; }
set
{
_isChanged |= (_personid != value);
_personid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public Employee Employee
{
get
{ return _employee; }
set
{ _employee = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Person castObj = (Person) obj;
return (castObj != null) &&
(_personid == castObj.PersonId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_personid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Employee
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _personid;
private string _job;
private Person _person;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Employee()
{
_personid = 0;
_job = null;
_person = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int PersonId
{
get
{ return _personid; }
set
{
_isChanged |= (_personid != value);
_personid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Job
{
get
{ return _job; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Job", value, value.ToString());
_isChanged |= (_job != value);
_job = value;
}
}
public Person Person
{
get
{ return _person; }
set
{ _person = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Employee castObj = (Employee) obj;
return (castObj != null) &&
(_personid == castObj.PersonId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_personid.GetHashCode();
return hash;
}
#endregion
}
}
1.3 示例映射文件
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne.Person,DDLLY.TestNHibernate.TestAssociation" table="T_Person">
<id name="PersonId" column="PersonId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<one-to-one name="Employee" class="DDLLY.TestNHibernate.TestAssociation.OneToOne.Employee,DDLLY.TestNHibernate.TestAssociation" cascade="all"></one-to-one>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne.Employee,DDLLY.TestNHibernate.TestAssociation" table="T_Employee">
<id name="PersonId" column="PersonId" type="Int32" unsaved-value="0">
<generator class="foreign">
<param name="property">Person</param>
</generator>
</id>
<property column="Job" type="String" name="Job" length="64" />
<one-to-one name="Person" class="DDLLY.TestNHibernate.TestAssociation.OneToOne.Person,DDLLY.TestNHibernate.TestAssociation" constrained="true"></one-to-one>
</class>
</hibernate-mapping>
1.4 说明
constrained（约束）: 表明该类对应的表对应的数据库表，和被关联的对象所对应的数据库表之间，通过一个外键引用对主键进行约束。这个选项影响Save()和Delete()在级联执行时的先后顺序（也在schema export tool中被使用）。
property-ref: (可选) 指定关联类的一个属性，这个属性将会和本外键相对应。如果没有指定，会使用对方关联类的主键。
<generator class="foreign">:表示使用另外一个相关联的对象的标识符，来创建主健。T_Employee的PersonId来自T_Person的ParentId。
Employee依赖于Person,所以通常在Person设置cascade。
2.另一种one-to-one
2.1数据库表结构
其中T_Person1为主表，T_Employee1为子表。T_Employee1的PersonId设置唯一约束，参照T_Person1的PersonId。
2.2示例映射类文件
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Person
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _personid;
private string _name;
private Employee _employee;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Person()
{
_personid = 0;
_name = null;
_employee = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int PersonId
{
get
{ return _personid; }
set
{
_isChanged |= (_personid != value);
_personid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public Employee Employee
{
get
{ return _employee; }
set
{ _employee = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Person castObj = (Person) obj;
return (castObj != null) &&
(_personid == castObj.PersonId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_personid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToOne1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Employee
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _employeeId;
private string _job;
private Person _person;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Employee()
{
_employeeId = 0;
_job = null;
_person = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int EmployeeId
{
get
{ return _employeeId; }
set
{
_isChanged |= (_employeeId != value);
_employeeId = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Job
{
get
{ return _job; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Job", value, value.ToString());
_isChanged |= (_job != value);
_job = value;
}
}
public Person Person
{
get
{ return _person; }
set
{ _person = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Employee castObj = (Employee) obj;
return (castObj != null) &&
(_employeeId == castObj.EmployeeId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_employeeId.GetHashCode();
return hash;
}
#endregion
}
}
2.3示例映射文件
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Person,DDLLY.TestNHibernate.TestAssociation" table="T_Person1">
<id name="PersonId" column="PersonId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<one-to-one name="Employee" class="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Employee,DDLLY.TestNHibernate.TestAssociation" cascade="all"></one-to-one>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Employee,DDLLY.TestNHibernate.TestAssociation" table="T_Employee1">
<id name="EmployeeId" column="EmployeeId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Job" type="String" name="Job" length="64" />
<many-to-one name="Person" class="DDLLY.TestNHibernate.TestAssociation.OneToOne1.Person,DDLLY.TestNHibernate.TestAssociation" column="PersonId" unique="true"></many-to-one>
</class>
</hibernate-mapping>
2.4说明
这种one-to-one实际上是一种特殊的one-to-many,如果T_Employee1的PersonId不设置唯一约束，则可成为one-to-many。所以在T_Employee端设置many-to-one而不是one-to-one,记住要加上unique="true"表示唯一约束。
3.one-to-many
3.1 数据库表结构
T_Parent为主表，T_Child的ParentId参照T_Parent的ParentId。
注意:对于单向的one-to-many映射,cascade过程中会用到把T_Child表的ParentId设置为Null,所以ParentId应设为允许NULL;
而双向one-to-many映射,建议把T_Child的ParentI设置为不允许NULL
3.2 示例映射类文件(单向)
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Parent
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _parentid;
private string _name;
private IList _children;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Parent()
{
_parentid = 0;
_name = null;
_children = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ParentId
{
get
{ return _parentid; }
set
{
_isChanged |= (_parentid != value);
_parentid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual IList Children
{
get
{ return _children; }
set
{
_isChanged |= (_children != value);
_children = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Parent castObj = (Parent) obj;
return (castObj != null) &&
(_parentid == castObj.ParentId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_parentid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany1
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Child
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _childid;
private string _name;
private int _parentid;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Child()
{
_childid = 0;
_name = null;
_parentid = 0;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ChildId
{
get
{ return _childid; }
set
{
_isChanged |= (_childid != value);
_childid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual int ParentId
{
get
{ return _parentid; }
set
{
_isChanged |= (_parentid != value);
_parentid = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Child castObj = (Child) obj;
return (castObj != null) &&
(_childid == castObj.ChildId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_childid.GetHashCode();
return hash;
}
#endregion
}
}
3.3 示例映射文件（单向）
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany1.Parent,DDLLY.TestNHibernate.TestAssociation" table="T_Parent">
<id name="ParentId" column="ParentId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<bag name="Children" cascade="all" lazy="true">
<key column="ParentId"/>
<one-to-many class="DDLLY.TestNHibernate.TestAssociation.OneToMany1.Child,DDLLY.TestNHibernate.TestAssociation"/>
</bag>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany1.Child,DDLLY.TestNHibernate.TestAssociation" table="T_Child">
<id name="ChildId" column="ChildId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<property column="ParentId" type="Int32" name="ParentId"/>
</class>
</hibernate-mapping>
3.4 示例映射类文件(双向)
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Parent
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _parentid;
private string _name;
private IList _children;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Parent()
{
_parentid = 0;
_name = null;
_children = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ParentId
{
get
{ return _parentid; }
set
{
_isChanged |= (_parentid != value);
_parentid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual IList Children
{
get
{ return _children; }
set
{
_isChanged |= (_children != value);
_children = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Parent castObj = (Parent) obj;
return (castObj != null) &&
(_parentid == castObj.ParentId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_parentid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
namespace DDLLY.TestNHibernate.TestAssociation.OneToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Child
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _childid;
private string _name;
private Parent _parent;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Child()
{
_childid = 0;
_name = null;
_parent = null;
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int ChildId
{
get
{ return _childid; }
set
{
_isChanged |= (_childid != value);
_childid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Name
{
get
{ return _name; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Name", value, value.ToString());
_isChanged |= (_name != value);
_name = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual Parent Parent
{
get
{ return _parent; }
set
{
_isChanged |= (_parent != value);
_parent = value;
}
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Child castObj = (Child) obj;
return (castObj != null) &&
(_childid == castObj.ChildId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_childid.GetHashCode();
return hash;
}
#endregion
}
}
3.5 示例映射类文件(双向)
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany.Parent,DDLLY.TestNHibernate.TestAssociation" table="T_Parent">
<id name="ParentId" column="ParentId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<bag name="Children" cascade="all" inverse="true" lazy="true">
<key column="ParentId"/>
<one-to-many class="DDLLY.TestNHibernate.TestAssociation.OneToMany.Child,DDLLY.TestNHibernate.TestAssociation"/>
</bag>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.OneToMany.Child,DDLLY.TestNHibernate.TestAssociation" table="T_Child">
<id name="ChildId" column="ChildId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="Name" type="String" name="Name" length="64" />
<many-to-one name="Parent" column="ParentId" class="DDLLY.TestNHibernate.TestAssociation.OneToMany.Parent,DDLLY.TestNHibernate.TestAssociation" />
</class>
</hibernate-mapping>
3.6 说明
在NHibernate配置文件中使用<set>, <list>, <map>, <bag>, <array> 和 <primitive-array>等元素来定义集合。<bag>是典型的一个，代码中我们用IList和它对应。我们以后会详细讲集合这个话题。
lazy表示允许延迟加载。表示在需要使用时才加载需要的数据。例如使用lazy时我们Load一个Parent他的Children为空，只有我们访问它的某一个Child时数据才会被加载；而不设置lazy我们Load一个Parent时其Children将同时加载。注意：使用lazy加载必须保证对应ISession的打开，否则懒加载会失败。
one-to-many可以设置单向和双向映射，设置单向时Child一段不设置many-to-one，而设置了ParentId的属性。
双向映射需要设置inverse而单向不需要。
单项映射在cascade时会对把T_Child的ParentId使用Update为Null的操作。
建议尽量使用双向映射。
4.many-to-many
4.1 数据库表结构
4.2 示例映射类文件
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.ManyToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class User
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _userid;
private string _username;
private string _password;
private string _email;
private IList _roles;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public User()
{
_userid = 0;
_username = null;
_password = null;
_email = null;
_roles = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int UserId
{
get
{ return _userid; }
set
{
_isChanged |= (_userid != value);
_userid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string UserName
{
get
{ return _username; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for UserName", value, value.ToString());
_isChanged |= (_username != value);
_username = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Password
{
get
{ return _password; }
set
{
if (value != null)
if (value.Length > 32)
throw new ArgumentOutOfRangeException("Invalid value for Password", value, value.ToString());
_isChanged |= (_password != value);
_password = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string Email
{
get
{ return _email; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for Email", value, value.ToString());
_isChanged |= (_email != value);
_email = value;
}
}
public IList Roles
{
get
{ return _roles; }
set
{ _roles = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
User castObj = (User) obj;
return (castObj != null) &&
(_userid == castObj.UserId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_userid.GetHashCode();
return hash;
}
#endregion
}
}
/**//*
/*作者：DDL
/*联系：http://renrenqq.cnblogs.com/
*/
using System;
using System.Collections;
namespace DDLLY.TestNHibernate.TestAssociation.ManyToMany
{
/**//// <summary>
///
/// </summary>
[Serializable]
public class Role
{
Private Members#region Private Members
private bool _isChanged;
private bool _isDeleted;
private int _roleid;
private string _rolename;
private IList _users;
#endregion
Default ( Empty ) Class Constuctor#region Default ( Empty ) Class Constuctor
/**//// <summary>
/// default constructor
/// </summary>
public Role()
{
_roleid = 0;
_rolename = null;
_users = new ArrayList();
}
#endregion // End of Default ( Empty ) Class Constuctor
Public Properties#region Public Properties
/**//// <summary>
///
/// </summary>
public virtual int RoleId
{
get
{ return _roleid; }
set
{
_isChanged |= (_roleid != value);
_roleid = value;
}
}
/**//// <summary>
///
/// </summary>
public virtual string RoleName
{
get
{ return _rolename; }
set
{
if (value != null)
if (value.Length > 64)
throw new ArgumentOutOfRangeException("Invalid value for RoleName", value, value.ToString());
_isChanged |= (_rolename != value);
_rolename = value;
}
}
public IList Users
{
get
{ return _users; }
set
{ _users = value; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsChanged
{
get
{ return _isChanged; }
}
/**//// <summary>
/// Returns whether or not the object has changed it's values.
/// </summary>
public bool IsDeleted
{
get
{ return _isDeleted; }
}
#endregion
Public Functions#region Public Functions
/**//// <summary>
/// mark the item as deleted
/// </summary>
public void MarkAsDeleted()
{
_isDeleted = true;
_isChanged = true;
}
#endregion
Equals And HashCode Overrides#region Equals And HashCode Overrides
/**//// <summary>
/// local implementation of Equals based on unique value members
/// </summary>
public override bool Equals(object obj)
{
if (this == obj) return true;
if ((obj == null) || (obj.GetType() != GetType())) return false;
Role castObj = (Role) obj;
return (castObj != null) &&
(_roleid == castObj.RoleId);
}
/**//// <summary>
/// local implementation of GetHashCode based on unique value members
/// </summary>
public override int GetHashCode()
{
int hash = 57;
hash = 27*hash*_roleid.GetHashCode();
return hash;
}
#endregion
}
}
4.3 示例映射文件
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.ManyToMany.User,DDLLY.TestNHibernate.TestAssociation" table="T_User">
<id name="UserId" column="UserId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="UserName" type="String" name="UserName" not-null="true" length="64" />
<property column="Password" type="String" name="Password" not-null="true" length="32" />
<property column="Email" type="String" name="Email" length="64" />
<bag name="Roles" table="T_User_Role" lazy="true">
<key column="UserId"/>
<many-to-many class="DDLLY.TestNHibernate.TestAssociation.ManyToMany.Role,DDLLY.TestNHibernate.TestAssociation" column="RoleId"/>
</bag>
</class>
</hibernate-mapping>
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="DDLLY.TestNHibernate.TestAssociation.ManyToMany.Role,DDLLY.TestNHibernate.TestAssociation" table="T_Role">
<id name="RoleId" column="RoleId" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<property column="RoleName" type="String" name="RoleName" not-null="true" length="64" />
<bag name="Users" table="T_User_Role" lazy="true" inverse="true">
<key column="RoleId"/>
<many-to-many class="DDLLY.TestNHibernate.TestAssociation.ManyToMany.User,DDLLY.TestNHibernate.TestAssociation" column="UserId"/>
</bag>
</class>
</hibernate-mapping>
4.4 说明
many-to-many性能不佳，数据量大时应尽可能避免使用。并尽可能使用lazy="true"。
在数据量少的一端设置inverse="true"，让数据量多的一段维护cascade。
二、cascade分析
1.总述
cascade：（默认为none）级联。指明哪些操作会从对象级联到关联的对象。
orphans：孤儿,没有夫对象的子对象。对于代码Child.Parent==null,对于数据库T_Child表中ParentId为Null的数据。
delete orphans表示cascade时删除孤儿。
一般系统中是不允许孤儿存在的，我们可以通过数据库的约束来限制孤儿，例如T_Child的ParentId设为Not NULL。
如果确实存在孤儿请考虑适合的cascade策略。
| cascade类型 | 对应操作 |
| all | Save / Delete / Update |
| all-delete-orphan | Save / Delete / Update + delete orphans |
| delete-orphan | Delete + delete orphans |
| none | No Cascades |
| delete | Delete |
| save-update | Save / Update |
a.初始化数据
| PersonId | Name | Job |
| 1 | DDL | 编程 |
| 2 | LLY | NULL |
TestAddPersonWithAddEmployee
Person person = new Person();
person.Name = "newPerson";
Employee employee = new Employee();
employee.Job = "newJob";
person.Employee = employee;
employee.Person = person;
session.Save(person);
TestUpdatePersonWithAddEmployee
Person person = session.Load(typeof (Person), 2) as Person;
person.Employee = new Employee();
person.Employee.Person = person;
person.Employee.Job = "LLYJob";
session.Update(person);
TestUpdatePersonWithUpdateEmployee
Person person = session.Load(typeof (Person), 1) as Person;
person.Employee.Job = "DDL'New Job";
session.Update(person);
TestDeletePersonWithDeleteEmployee
Person person = session.Load(typeof (Person), 1) as Person;
session.Delete(person);
c.测试结果
| 测试方法 | save-update | delete | delete-orphan | all | all-delete-orphan | none |
| TestAddPersonWithAddEmployee | Y | N | N | Y | Y | N |
| TestUpdatePersonWithAddEmployee | Y | N | N | Y | Y | N |
| TestUpdatePersonWithUpdateEmployee | Y | Y | Y | Y | Y | Y |
| TestDeletePersonWithDeleteEmployee | N | Y | Y | Y | Y | N |
a.初始化数据
| PersonId | Name | EmployeeId | Job |
| 1 | DDL | 1 | 编程 |
| 2 | LLY | NULL | NULL |
TestAddPersonWithAddEmployee
不支持
TestUpdatePersonWithAddEmployee
Person person = session.Load(typeof (Person), 2) as Person;
person.Employee = new Employee();
person.Employee.Person = person;
person.Employee.Job = "LLYJob";
session.Update(person);
session.Flush();
TestUpdatePersonWithUpdateEmployee
Person person = session.Load(typeof (Person), 1) as Person;
person.Employee.Job = "DDL'New Job";
session.Update(person);
session.Flush();
TestDeletePersonWithDeleteEmployee
Person person = session.Load(typeof (Person), 1) as Person;
session.Delete(person);
session.Flush();
c.测试结果
| 测试方法 | save-update | delete | delete-orphan | all | all-delete-orphan | none |
| TestAddPersonWithAddEmployee | 不支持 | 不支持 | 不支持 | 不支持 | 不支持 | 不支持 |
| TestUpdatePersonWithAddEmployee | Y | N | N | Y | Y | N |
| TestUpdatePersonWithUpdateEmployee | Y | Y | Y | Y | Y | Y |
| TestDeletePersonWithDeleteEmployee | N | Y | Y | Y | Y | N |
a.初始化数据
| ParentId | ParentName | ChildId | ChildName |
| 1 | Parent1 | 1 | Child1 |
| 2 | Parent2 | NULL | NULL |
TestAddParentWithAddChild
Parent parent = new Parent();
parent.Name = "NewParent";
Child child = new Child();
child.Name = "NewChild";
child.Parent = parent;
parent.Children.Add(child);
session.Save(parent);
session.Flush();
TestUpdateParentWithAddChild
Parent parent = session.Load(typeof (Parent), 2) as Parent;
Child child = new Child();
child.Name = "NewChild";
child.Parent = parent;
parent.Children.Add(child);
session.Update(parent);
session.Flush();
TestUpdateParentWithUpdateChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
Child child = (Child) parent.Children[0];
child.Name = "UpdateName";
session.Update(parent);
session.Flush();
TestDeleteParentWithChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
session.Delete(parent);
session.Flush();
c.测试结果
| 测试方法 | save-update | delete | delete-orphan | all | all-delete-orphan | none |
| TestAddParentWithAddChild | Y | N | N | Y | Y | N |
| TestUpdateParentWithAddChild | Y | N | N | Y | Y | N |
| TestUpdateParentWithUpdateChild | Y | Y | Y | Y | Y | Y |
| TestDeleteParentWithChild | N | Y | Y | Y | Y | N |
a.初始化数据
同上
b.测试方法
TestAddParentWithAddChild
不支持
TestUpdateParentWithAddChild
Parent parent = session.Load(typeof (Parent), 2) as Parent;
Child child = new Child();
child.Name = "NewChild";
child.ParentId = parent.ParentId;
parent.Children.Add(child);
session.Update(parent);
session.Flush();
TestUpdateParentWithUpdateChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
Child child = (Child) parent.Children[0];
child.Name = "UpdateName";
session.Update(parent);
session.Flush();
TestDeleteParentWithChild
Parent parent = session.Load(typeof (Parent), 1) as Parent;
session.Delete(parent);
session.Flush();
c.测试结果
| 测试方法 | save-update | delete | delete-orphan | all | all-delete-orphan | none |
| TestAddParentWithAddChild | 不支持 | 不支持 | 不支持 | 不支持 | 不支持 | 不支持 |
| TestUpdateParentWithAddChild | Y | N | N | Y | Y | N |
| TestUpdateParentWithUpdateChild | Y | Y | Y | Y | Y | Y |
| TestDeleteParentWithChild | Parent被删除，Child成为孤儿 | Y | Y | Y | Y | Parent被删除，Child成为孤儿 |
many-to-many和别的关联映射有所不同。例子中：Role和User没有直接的依赖关系，而是通过一张中间表完成。在删除User时一般不会要求删除Role，而是删除之间的关系（即从中间表删除数据）。
a.初始化数据
| UserId | UserName | Password | RoleId | RoleName | |
| 1 | DDL | 1 | NULL | 1 | 角色1 |
| 1 | DDL | 1 | NULL | 2 | 角色2 |
| 2 | LLY | 2 | NULL | 1 | 角色1 |
| 3 | 陌生人 | 3 | NULL | NULL | NULL |
| NULL | NULL | NULL | NULL | 3 | 角色3 |
TestAddRoleToUser
User user = session.Load(typeof (User), 1) as User;
Role role = session.Load(typeof (Role), 3) as Role;
user.Roles.Add(role);
role.Users.Add(user);
session.Update(user);
session.Flush();
TestRemoveRoleFromUser
User user = session.Load(typeof (User), 1) as User;
Role role = session.Load(typeof (Role), 2) as Role;
user.Roles.Remove(role);
role.Users.Remove(user);
session.Update(user);
session.Flush();
TestUpdateUserWithRole
User user = session.Load(typeof(User), 2) as User;
((Role) user.Roles[0]).RoleName = "UpdateRole";
session.Update(user);
session.Flush();
TestDeleteUserWithSetRole
User user = session.Load(typeof (User), 1) as User;
session.Delete(user);
session.Flush();
c.测试结果
| 测试方法 | save-update | delete | delete-orphan | all | all-delete-orphan | none |
| TestAddRoleToUser | Y | Y | Y | Y | Y | Y |
| TestRemoveRoleFromUser | Y | Y | Y | Y | Y | Y |
| TestUpdateUserWithRole | Y | Y | Y | Y | Y | Y |
| TestDeleteUserWithSetRole | N | Uer被删除,但和其有关的Role也被删除 | Uer被删除,但和其有关的Role也被删除 | Uer被删除,但和其有关的Role也被删除 | Uer被删除,但和其有关的Role也被删除 | N |
关联是NHibernate里面功能很强的一块，但也使很容易滥用而造成引起性能或其他问题的地方。所以请慎重的使用。
在使用之前，请考虑好以下问题：
1.关系分析，一对多，多对多，还是一对一。
2.确定依赖关系，例如：Child依赖于Parent。
3.是否允许存在孤儿，例如：存在Child没有Parent（即在数据库中ParentId为Null的Child）。
4.在对等的关系中是否有主动端。例如：需要给Parent设置Child还是给Child找Parent，或者两边都可以操作。
5.关联两端可能出现的数据量以及在页面显示时是否分页。如果数据量大或者页面上需要分页显示，建议不要采用关联映射。如果数据量大，性能会不好，如果需要分页，关联所有数据似乎没有什么意思。
6.页面上可能的对象操作方法。例如：先读取一个Parent，然后添加Child，然后保存。
请根据你的情况设置关联映射，而对于cascade标准的设置可以满足绝大多数的需要，如一有特殊情况，请按照上面的分析选择合适的。
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