NHibernate属性配置

Question

In the NHibernate, I have this config.

 <property name="Name" type="System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a222222229">
      <column name="Name" />
    </property>

what these mean ? msconrlib, version, culture, publicKeyToken ? why we need these ? I have worked on Hibernate in java env, I never use these tags.

Thanks

Answer 1

Type describes the .Net CLR type to be used for that property. In this case an ordinary string.

You dont have to specify it in this case. There are cases when you want to specify it, for example when you are working with custom types. Or when you want to map a DateTime.

Regarding the meaning of the parts of the type: The type is System.String, it is very precisely described regarding assembly name, culture and version. The publicKeyToken is a key for a strong name for the assembly - this allows for duplicate assembly names as long as they are signed with different keys.

You could write this mapping as

 <property name="Name">
      <column name="Name" />
 </property>

or

<property name="Name" type="String">
      <column name="Name" />
</property>

But if you wanted to use a custom type in some assembly you would need to specify if more detailed like you are doing right now.

Answer 2

In MS .Net it's called Strong assembly name. It's how specific type is identified in .Net Framework. So this particular string states that to use System.string from mscorlib library with version 4.0. with no preferences on localization. This allows .Net to use assemblies deployed to GAC - Global Assembly Cache which acts as a global directory of system dlls.