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POUpdating objects in GAE
 

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    <p>I have a problem that I can't be able to solve. I've tried to search on the web for solutions, but I didn't find any generic solution. I want to update an object, whatever it's class may be, in the datastore. For that, here's the code I'm using for the project</p> <p>I'm using DataNucleus and Google AppEngine.</p> <p>Here's my jdoconfig.xml</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;jdoconfig xmlns="http://java.sun.com/xml/ns/jdo/jdoconfig" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://java.sun.com/xml/ns/jdo/jdoconfig"&gt; &lt;persistence-manager-factory name="transactions-optional"&gt; &lt;property name="javax.jdo.PersistenceManagerFactoryClass" value="org.datanucleus.store.appengine.jdo.DatastoreJDOPersistenceManagerFactory"/&gt; &lt;property name="javax.jdo.option.ConnectionURL" value="appengine"/&gt; &lt;property name="javax.jdo.option.NontransactionalRead" value="true"/&gt; &lt;property name="javax.jdo.option.NontransactionalWrite" value="true"/&gt; &lt;property name="javax.jdo.option.RetainValues" value="true"/&gt; &lt;property name="datanucleus.appengine.autoCreateDatastoreTxns" value="true"/&gt; &lt;/persistence-manager-factory&gt; &lt;/jdoconfig&gt; </code></pre> <p>My PMF class</p> <pre><code>public final class PMF { private static final PersistenceManagerFactory pmfInstance = JDOHelper.getPersistenceManagerFactory("transactions-optional"); private PMF() {} public static PersistenceManagerFactory get() { return pmfInstance; } public static PersistenceManager getPersistenceManager() { return pmfInstance.getPersistenceManager(); } } </code></pre> <p>My BaseModel class, wich is a superclass for all the models of the project</p> <pre><code>@Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE) @PersistenceCapable(detachable = "true", identityType = IdentityType.APPLICATION) public abstract class BaseModel implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) protected Key id; public boolean equals(Object obj) { try { return obj instanceof BaseModel ? this.getId().getId() == ((BaseModel) obj).getId().getId() : false; } catch (Exception e) { return false; } } } </code></pre> <p>Here's the class (<code>Project</code>) I want to save</p> <pre><code>@PersistenceCapable(detachable = "true", identityType = IdentityType.APPLICATION) public class Project extends BaseModel implements BeanModelTag { private static final long serialVersionUID = 3318013676594981107L; @Persistent private String name; @Persistent private String description; @Persistent private Date deadline; @Persistent private Integer status; @Persistent private Key manager; @Persistent private Set&lt;Key&gt; team; } </code></pre> <p>For that, I tried several things. This method below saves a NEW instance of Project with success, but when I call to for updating an already detached object, only the field <em>deadline</em> is updated, the other attributes aren't updated (and yet, I went in debug mode to check out if the other attributes where changed, and yes, they were, but only deadline get's saved).</p> <pre><code>public void save(BaseModel object) { PersistenceManager pm = PMF.getPersistenceManager(); try { pm.makePersistent(object); } finally { pm.close(); } } </code></pre> <p>So, I tried the following code</p> <pre><code>public void update(Project object) { PersistenceManager pm = PMF.get().getPersistenceManager(); try { pm.currentTransaction().begin(); Project p = pm.getObjectById(Project.class, object.getId()); p.setName(object.getName()); p.setDeadline(object.getDeadline()); p.setDescription(object.getDescription()); p.setTeam(p.getTeam()); p.setStatus(object.getStatus()); pm.currentTransaction().commit(); } catch (Exception e) { e.printStackTrace(); pm.currentTransaction().rollback(); } finally { pm.close(); } } </code></pre> <p>And it worked. Ok, it works in this way, but I need a generic method for all my models, so I tried this</p> <pre><code>public void update(BaseModel object) { PersistenceManager pm = PMF.get().getPersistenceManager(); try { pm.currentTransaction().begin(); BaseModel ob = pm.getObjectById(object.getClass(), object.getId()); for (Field f : ob.getClass().getDeclaredFields()) { if (!f.toString().contains("final")) { f.setAccessible(true); for (Field g : object.getClass().getDeclaredFields()) { g.setAccessible(true); if (f.getName().equals(g.getName())) { f.set(ob, g.get(object)); } g.setAccessible(false); } } f.setAccessible(false); } pm.makePersistent(ob); pm.currentTransaction().commit(); } catch (Exception e) { e.printStackTrace(); pm.currentTransaction().rollback(); } finally { pm.close(); } } </code></pre> <p>But it doesn't work at all, nothing gets saved, and yet when I System.out the attributes manually, they are changed. I tried with and without <code>pm.makePersistent(ob);</code> with no luck. I don't know what to do. I have 120 models in this project that inherits from <code>BaseModel</code> and I can't find a way to make an update that works with my model.</p> <h2>----------- Edit -----------</h2> <p>Thanks for the answer. Here's my solution for now. Of course, that printStrackTree will get out of there.</p> <pre><code>public void update(BaseModel object) { PersistenceManager pm = PMF.get().getPersistenceManager(); try { pm.currentTransaction().begin(); BaseModel ob = pm.getObjectById(object.getClass(), object.getId()); for (Field f : ob.getClass().getDeclaredFields()) { if (!Pattern.compile("\\bfinal\\b").matcher(f.toString()).find()) { f.setAccessible(true); for (Field g : object.getClass().getDeclaredFields()) { g.setAccessible(true); if (f.getName().equals(g.getName())) { f.set(ob, g.get(object)); JDOHelper.makeDirty(ob, f.getName()); } g.setAccessible(false); } f.setAccessible(false); } } pm.makePersistent(object); pm.currentTransaction().commit(); } catch (Exception e) { e.printStackTrace(); pm.currentTransaction().rollback(); } finally { pm.close(); } } </code></pre>
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