title: Fluent NHibernate mapping non Id Guid to Oracle
body: <p>I'm trying to map a Guid, which is not an Id property, to an Oracle CLOB column.</p>
  
  <p>In MsSQL I can map Guid to a <code>UniqueIdentifier</code> column as follows:</p>
  
  <pre><code>Map(x =&gt; x.Guid).Column("my_guid").CustomType&lt;GuidType&gt;();
  </code></pre>
  
  <p>and I generate the Guid in the constructor of my business entity:</p>
  
  <pre><code>public MyEntity()
  {
      this.Guid = Guid.NewGuid();
  }
  </code></pre>
  
  <p>However, when attempting to map Guid to a CLOB in Oracle, using the same mapping that works for MsSQL, it is always inserting a NULL value.</p>
  
  <p>It would be convenient if this problem could be solved similar to how you map a Guid Id field:</p>
  
  <pre><code>Id(x =&gt; x.Id).Column("my_guid").GeneratedBy.GuidComb();
  </code></pre>