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POUpdated JDO objects will not persist in GWT
 

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  1. POUpdated JDO objects will not persist in GWT
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    <p>I'm writing a small application using GWT and JDOs to store persistent data. I've been trying to write a function that updates multiple JDO objects based on a query. Its body looks something like this:</p> <pre><code>PersistenceManager pm = getPersistenceManager(); try { q = pm.newQuery(MyObject.class, query); List&lt;MyObject&gt; objects = (List&lt;MyObject&gt;) q.execute(); for (MyObject object: objects) { object.setMyField(newValue); } System.out.println(objects); //[1] } finally { pm.close(); } </code></pre> <p>If I look at the output of the print statement at [1], the objects all have the correctly updated values. When I make an RPC to retrieve the updated objects, however, the values are the same as they were before the update method was called. If I check the datastore in the admin panel, the updates also do not appear.</p> <p>All the other persistence behaviour in my application works fine (e.g. adding new objects, removing objects, querying objects), but I can't seem to figure out what's wrong here. Most of the resources I've found (like <a href="http://code.google.com/appengine/docs/java/datastore/jdo/creatinggettinganddeletingdata.html#Updating_an_Object" rel="nofollow">http://code.google.com/appengine/docs/java/datastore/jdo/creatinggettinganddeletingdata.html#Updating_an_Object</a>) suggest that just having the PersistenceManager open should persist any changes you make to retrieved objects.</p> <p>Any suggestions? I am truly baffled.</p> <p>Thank you!</p> <p><strong>SOLUTION</strong></p> <pre><code>PersistenceManager pm = getPersistenceManager(); try { q = pm.newQuery(MyObject.class, query); List&lt;MyObject&gt; objects = (List&lt;MyObject&gt;) q.execute(); for (MyObject object: objects) { object.setMyField(newValue); JDOHelper.makeDirty(object, myField); } } finally { pm.close(); } </code></pre>
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    1. COOf course as soon as I post this I find the related post with the answer. I'll just leave this here: http://stackoverflow.com/questions/7486710/updating-objects-in-gae
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    2. COObviously that's not a real answer. You retrieve objects non-transactional, so they are in what state ? (JDOHelper.getObjectState(obj) tells you). Any setter will make that field dirty (read the log, it tells you). You then never start a new txn, hence any changes don't go to the DB (using GAE v2 plugin the pm.close will certainly flush all remaining changes).
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