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POGeneric DAO and nested properties support
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  1. POGeneric DAO and nested properties support
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    copied!<p>I am trying to perform a DB access through a DAO object, and I have bumped into the case where I need to query a field in another Entity.</p> <p>Considering two entities (EntityA and EntityB) that are connected in entity A through the foreign key <code>EntityA.idEntityB</code>.</p> <p>I have <code>GenericDao&lt;EntityA&gt; daoA</code> and I am trying to get all the results that match a determined field of EntityB: <code>idEntityB.fieldOfB</code> all in the same <em>find</em> method of the dao. </p> <p>Is it possible? And if so some directions would be nice. Thanks</p> <p><strong>edit</strong></p> <p>An example of my code: </p> <h3>Entities</h3> <pre><code>public class EntityA { @JoinColumn(name = "id_entity_b", referencedColumnName = "id") @ManyToOne(optional = false, fetch = FetchType.EAGER) private EntityB idEntityB; // getter+setter... } public class EntityB { // ... private String fieldOfB; // getter+setter... } </code></pre> <h3>DAO Access</h3> <pre><code>GenericDao&lt;EntityA&gt; daoA = // ... Set&lt;Criterion&gt; filter = new HashSet&lt;Criterion&gt;(); filter.add(Restrictions.eq("idEntityB.fieldOfB")); List&lt;EntityA&gt; list = dao.findByFilter(filter); </code></pre> <p>The error message is something like "<em>Could not resolve property idEntityB.fieldOfB</em>"</p> <p><strong>edit 2</strong></p> <p>I was able to find something like what I want to do. Although my API is slightly different I believe this is helful for anyone who gets across this problem at an early stage of their own project.</p> <p><a href="http://code.google.com/p/hibernate-generic-dao/" rel="nofollow">http://code.google.com/p/hibernate-generic-dao/</a></p> <blockquote> <p>The framework features a powerful and flexible search functionality. This is used by passing a search object to search methods on general and generic DAOs.</p> </blockquote> <p>Searches with nested properties are fully supported in this project.</p>
 

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