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POForce refresh of collection JPA entityManager
 

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    <p>I am using SEAM with JPA (implemented as a Seam Managed Persistance Context), in my backing bean I load a collection of entities (ArrayList) into the backing bean.</p> <p>If a different user modifies one of the entities in a different session I want these changes to be propagated to the collection in my session, I have a method <code>refreshList()</code> and have tried the following...</p> <pre><code>@Override public List&lt;ItemStatus&gt; refreshList(){ itemList = itemStatusDAO.getCurrentStatus(); } </code></pre> <p>With the following query</p> <pre><code>@SuppressWarnings("unchecked") @Override public List&lt;ItemStatus&gt; getCurrentStatus(){ String s = "SELECT DISTINCT iS FROM ItemStatus iS "; s+="ORDER BY iS.dateCreated ASC"; Query q = this.getEntityManager().createQuery(s); return q.getResultList(); } </code></pre> <p>Re-executing the query, this just returns the same data I already have (I assume it is using the 1st level cache rather than hitting the database)</p> <pre><code>@Override public List&lt;ItemStatus&gt; refreshList(){ itemStatusDAO.refresh(itemList) } </code></pre> <p>Calling <code>entityManager.refresh()</code>, this should refresh from the database however I get a <code>javax.ejb.EJBTransactionRolledbackException: Entity not managed</code> exception when I use this, normally I would use <code>entityManager.findById(entity.getId)</code> before calling .refresh() to ensure it is attached to the PC but as I am refreshing a collection of entities I cant do that.</p> <p>It seems like quite a simple problem, I cant believe there is no way to force JPA/hibernate to bypass the cache and hit the database?!</p> <p>UPDATE TEST CASE:</p> <p>I am using two different browsers (1 and 2) to load the same web page, I make a modification in 1 which updates a boolean attribute in one of the ItemStatus entities, the view is refreshed for 1 to display the updated attribute, I check the database via PGAdmin and the row has been updated. I then press refresh in Browser 2 and the attribute has not been updated</p> <p>I tried using the following method to merge all entities before calling .refresh, but the entities were still not updated from the database.</p> <pre><code>@Override public void mergeCollectionIntoEntityManager(List&lt;T&gt; entityCollection){ for(T entity: entityCollection){ if(!this.getEntityManager().contains(entity)){ this.getEntityManager().refresh(this.getEntityManager().merge(entity)); } } } </code></pre>
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    1. CODid you merge your objects back into the entity manager prior to calling refresh?
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    2. CONo I didn't, the merge() method doesnt accept collections and I thought calling it on every member of the collection is a bit excessive?
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    3. COIt could be, if you have a really large list. But normal merges just synchronize the object state to the entity managers unit of work and are very fast. If merging takes too long you could always boot everything out of the second level cache with `entityMgr.getEntityManagerFactory().getCache().evictAll()`.
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