这几天一直在查博客,发现NHibernate并不好用:
1.两张表完全没有主外键关系的时候,能用NHibernate吗?
2.两张表(比如订单,里面关联一个customer Name 通过customerID 关联)要关联查询某一个字段,而在子表中(比如上面的订单表)没有明显的外键,这时候在<join>标签中指定property-ref属性是完全不起作用的.(测试了一下,这时候无论你是否指定了property-ref NH都是默认用两张表的主键做关联的)
问题:NHibernate完全不适合两张毫无关系(数据库表建立的关系,而不是逻辑关系)的查询.
3.数据表中如果有冗余字段(比如上面订单中,除了CustomerID额外冗余CustomerName),这时候getter和setter的映射关系就比较难处理.
4.NH在建立关系映射的时候,非得指定Many-to-one,many-to-many等几种,映射关系,在查询的时候,有时候并不需要将one-to-many中的many查出来,插入的时候,可能并不需要初始化many,这种笨重的写法,实在不明白是不是设计的缺陷.关于这个国外的网站会提供下面的代码.
/// <summary>
/// There are no comments for NHibernate_Console.Person, NHibernate_Console in the schema.
/// </summary>
public partial class Person {

#region Extensibility Method Definitions

/// <summary>
/// There are no comments for OnCreated in the schema.
/// </summary>
partial void OnCreated();

#endregion
/// <summary>
/// There are no comments for Person constructor in the schema.
/// </summary>
public Person()
{
OnCreated();
}

/// <summary>
/// There are no comments for Id in the schema.
/// </summary>
public virtual int Id
{
get;
set;
}

/// <summary>
/// There are no comments for Name in the schema.
/// </summary>
public virtual string Name
{
get;
set;
}

/// <summary>
/// There are no comments for Address in the schema.
/// </summary>
public virtual string Address
{
get;
set;
}
public virtual string GradeName
{
get;
set;
}

/// <summary>
/// There are no comments for GradeId in the schema.
/// </summary>
public virtual System.Nullable<int> GradeId
{
get;
set;
}

/// <summary>
/// There are no comments for ThisGrade in the schema.
/// </summary>
public virtual Grade ThisGrade
{
get;
set;
}
}

#region Extensibility Method Definitions

/// <summary>
/// There are no comments for OnCreated in the schema.
/// </summary>
partial void OnCreated();

#endregion
/// <summary>
/// There are no comments for Grade constructor in the schema.
/// </summary>
public Grade()
{
this.Persons = new List<Person>();
OnCreated();
}

/// <summary>
/// There are no comments for Id in the schema.
/// </summary>
public virtual int Id
{
get;
set;
}

/// <summary>
/// There are no comments for Name in the schema.
/// </summary>
public virtual string Name
{
get;
set;
}

/// <summary>
/// There are no comments for Note in the schema.
/// </summary>
public virtual string Note
{
get;
set;
}

/// <summary>
/// There are no comments for Persons in the schema.
/// </summary>
public virtual IList<Person> Persons
{
get;
set;
}
}

=== 执行插入的时候:

public int Add(Person person)
{
using (ISession _session = NHibernateHelper.OpenSession())
{
using (ITransaction _tran = _session.BeginTransaction())
{

var _grade = _session.Get<Grade>(22);
person.ThisGrade = _grade;
_grade.Persons = new List<Person> { person};
_session.Save(_grade); //这里差点看成无限递归了
_session.Save(person);
_tran.Commit();
return 0;
}
}
}