Home/ Questions/Q 602397
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-13T16:49:06+00:00

Let’s say that I have a class/table called Images that, as it stands right

  • 0

Let’s say that I have a class/table called Images that, as it stands right now, is bound in a manner similar to this:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="Domain.Image, Domain" table="Images">
    <id name="id" column="ImageID" access="field" unsaved-value="0">
      <generator class="identity" />
    </id>    
<!-- other properties -->
    <property name="AssociatedObjectID" column="AssociatedObjectID" />
    <property name="AssociatedObjectType" column="AssociatedObjectType" />
  </class>
</hibernate-mapping>

Up until this point, this schema has worked, because a image was only associated with one object, so I could keep that reference without a discriminator.

However, now I wish to have a collection of these images on another entity called a PhotoShoot. Each PhotoShoot can have several images.

Is there a way to bind a collection such that I can have a List<Image> within PhotoShoot without extracting a base class and using the table-per-hierarchy inheritance pattern?

And if not, is table-per-hierarchy really the best way to go here? I hate to create subclasses, especially since there is nothing that needs to be abstracted from the Image entity.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    I would map this as an IList<Images> property on PhotoShoot, mapped via a join table (many-to-many).

    If the ordering of the list is important, map as a list otherwise as a bag. I have included both mappings.

    <class name="Domain.PhotoShoot, Domain" table="PhotoShoot">
    <id name="id" column="PhotoShootId" access="field" unsaved-value="0">
      <generator class="identity" />
    </id>    
    <!-- other properties -->

    <!-- unordered list -->
    <bag name="Images" table="PhotoShoot_Image" fetch="join" cascade="all-delete-orphan">
        <key column="PhotoShootId"/>
        <many-to-many class="Domain.Image, Domain" column="ImageId" />
    </bag>

    <!-- ordered list -->
    <list name="Images" table="PhotoShoot_Image" fetch="join" cascade="all-delete-orphan">
        <key column="PhotoShootId"/>
        <imdex column="position" />
        <many-to-many class="Domain.Image, Domain" column="ImageId" />
    </list>
</class>

public class PhotoShoot
{
    IList<Image> Images { get; set; }
}

    Using @ddango’s original class mapping we could instead do the following.

    <class name="Domain.PhotoShoot, Domain" table="PhotoShoot">
    <bag name="Images" table="Image" fetch="join" where="AssociatedObjectType='PhotoShoot'">
        <key column="AssociatedObjectId"/>
        <one-to-many class="Domain.Image, Domain" />
    </bag>
</class>
    • 0