使用Fluent NHibernate映射大字符串

我正在使用Oracle DB,我正在尝试映射这个类:

public class Book { public virtual int Id { get; private set; } public virtual string Author { get; set; } public virtual string Title { get; set; } public virtual string Text { get; set; } } 

使用此映射类:

 public class BookMap : ClassMap { public BookMap() { Id(x => x.Id); Map(x => x.Author); Map(x => x.Title); Map(x => x.Text); } } 

但它生成的列类型是NVARCHAR(255), Book.Text属性有超过255个字符。

如何将其映射到可以包含非常大的字符串的类型(例如CLOB)?

 public class BookMap : ClassMap { public BookMap() { Id(x => x.Id); Map(x => x.Author); Map(x => x.Title); Map(x => x.Text).CustomSqlType("CLOB"); } } 

要么

 public class BookMap : ClassMap { public BookMap() { Id(x => x.Id); Map(x => x.Author); Map(x => x.Title); Map(x => x.Text).Length(500); // nvarchar(500) } }