NHibernate default child collection and criteria strategies

Question

In the domain model, there are a number of entities that have a Status enum with values of either Active or Deleted.

I'm looking for documentation and advice on recommended approaches on how to handle:

1. When fetching a collection of entities that have a Status enum, to exclude those with the value set to Deleted by default (overridable on a case by case basis)

2. When fetching a child collection of entities, by default to exclude those with the value set to Deleted by default.

In summary, I effectively want to keep all data relating to entities with a Status enum property, but to exclude those that have a value of Deleted for status by default.

Any pointers in the right direction much appreciated.

Answer 1

You can use a feature in nhibernate called a filter.

Example:

  <class name="Post"  table="Posts">
     <id name="Id">
        <generator class="identity"/>
     <id>

    <property name="Title"/>
    <property name="Text"/>
    <property name="PostedAt"/>


    <filter name="NoDeleted" condition="Status <> 'Deleted'"/>
</class>

Then when you query:

 session.EnableFilter("NoDeleted")

For more: http://ayende.com/blog/3993/nhibernate-filters