初次接触NHibernate遇到的问题及解决方法

今天初学NHibernate, 试着做了一个demo，遇到两个问题，在网上查了一下，解决了一个，另外一个靠经验解决了.

问题1 出现Could not compile the mapping document

问题出在你所使用的NHibernate的版本与你在配置文件中所设的不一致，例如，在配置文件中有如下信息,

<section name="nhibernate" type="System.Configuration.NameValueSectionHandler, System, Version=1.0.5000.0,Culture=neutral, PublicKeyToken=b77a5c561934e089" />

而你所引用的NHibernate.dll可能是最新的版本，于是就会出现这个问题.这时有一个简单的办法，就是到你存放NHibernate的文件夹下找到一个名为NHibernate.Examples.dll的文件，以文本文件打开，复制里面所有的内容，覆盖掉你配置文件里的所有内容，即可解决Could not compile the mapping document的问题.当然，别忘了更改数据库连接字符串!

问题2    The following types may not be used as proxies:
         Test.Model.Person: method set_Id should be virtual
         Test.Model.Person: method get_Name should be virtual
         Test.Model.Person: method set_Name should be virtual

         Test.Model.Person: method get_Id should be virtual

　　 网上搜到的三种解决方案：

1.   You can follow the advice of the exception and add "virtual" to all of your properties, and make sure your class is non-sealed. Obviously you'll want to do this if you think you might want to take advantage of the lazy-initializing proxy feature.   However, changing your classes may not be practical or advisable if you have a legacy codebase, or it may just bother you that a "transparent" persistence framework is dictating how you design certain aspects of your value classes.   That's where Options 2 and 3 come in.   Both of those involve changing back to the old behavior.

2.  To change the lazy-initialization proxy setting for a specific class, you can add a "lazy='false'" attribute to the <class> mapping element.   This might look something like:

<class
     name="NorthwindClasses.Category, NorthwindClasses"
     table="Categories"
     lazy="false"
>

3.  To change the lazy-initialization proxy setting for all classes in a given mapping file, you can add a "default-lazy='false'" attribute to the <hibernate-mapping> element, as follows:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0" default-lazy="false">

Unfortunately, Option 3 doesn't really help you much if you do one <class> mapping per <hibernate-mapping> file, a practice which I personally follow and recommend.   It's too bad, but there doesn't seem to be any way to set this default in the <nhibernate> global configuration.   But if you do happen to have all of your <class>'s in one .hbm.xml file, "default-lazy" can help you out.