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POAutomatically updating corresponding collection in NHibernate?
 

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    <p>My database has two tables:</p> <pre><code>Users UserId PK Likes LikeId PK LikedUserId FK LikingUserId FK </code></pre> <p>These tables represent user 'likes'. Likes are directional - user A likes user B, but user B does not like user A.</p> <p>I am mapping with NHibernate like this:</p> <pre><code>&lt;class name="User" table="Users"&gt; &lt;id name="UserId"&gt; &lt;generator class="assigned"&gt;&lt;/generator&gt; &lt;/id&gt; &lt;idbag name="LikedBy" table="Likes" inverse="true"&gt; &lt;collection-id column="LikeId" type="guid"&gt; &lt;generator class="guid.comb"/&gt; &lt;/collection-id&gt; &lt;key column="LikedUserId"/&gt; &lt;many-to-many column="LikingUserId" class="User"/&gt; &lt;/idbag&gt; &lt;idbag name="Liking" table="Likes"&gt; &lt;collection-id column="LikeId" type="guid"&gt; &lt;generator class="guid.comb"/&gt; &lt;/collection-id&gt; &lt;key column="LikingUserId"/&gt; &lt;many-to-many column="LikedUserId" class="User"/&gt; &lt;/idbag&gt; &lt;/class&gt; </code></pre> <p>Corresponding to this class:</p> <pre><code>public class User { public Guid UserId { get; set; } public ICollection&lt;User&gt; LikedBy { get; set; } public ICollection&lt;User&gt; Liking { get; set; } } </code></pre> <p>This works fine. However, the <code>Liking</code> and <code>LikedBy</code> collections for two different users can get out of sync. For instance:</p> <pre><code>using (var session = new NHibHelp.OpenSession()) { var user1 = session.GetById&lt;User&gt;(id1); var user2 = session.GetById&lt;User&gt;(id2); int initialCount = user2.LikedBy.Count(); user1.Liking.Add(user2); session.Update(user1); int finalCount = user2.LikedBy.Count(); Assert.AreEqual(initalCount,finalCount); // passes } </code></pre> <p>So if I add to the <code>Liking</code> collection of one user, the <code>LikedBy</code> collection of another user is not updated. To have it updated, I need to do <code>Session.Refresh()</code>.</p> <p>This isn't ideal. I'm quite new to NHibernate, so I don't know if there is another solution - is there anything better I can do? For instance, is it possible to map this scenario in such a way that <code>LikedBy</code> is automatically updated when appropriate?</p>
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