Am I doing these JDO operations wrong or is there a bug/limitation in
the appengine JDO implementation?
Using JDO, I can persist new entities in the datastore that contain a
serialized collection and read them back. But when I attempt to
update an existing entity, it persists the changes to all properties
except the serialized collection. Is there some way I'm supposed to
indicate that the serialized collection has changed and therefore
needs to be persisted?
Here is some test code that demonstrates the problem. Relevant output
follows the code.
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class SerialTest2
{
@SuppressWarnings("unused")
@PrimaryKey
@Persistent
private String key;
@Persistent
private String testString;
@Serialized
ArrayList<String> testStrings;
public SerialTest2()
{
}
public void setKey(String key)
{
this.key = key;
}
public void setTestString(String testString)
{
if (testStrings == null)
{
testStrings = new ArrayList<String>();
}
this.testString = testString;
this.testStrings.add(testString);
}
public String getTestString()
{
return this.testString;
}
public ArrayList<String> getTestStrings()
{
return this.testStrings;
}
}
log.info("Insert/Update
------------------------------------");
List<SerialTest2> st2List = null;
PersistenceManager pm = PMF.get().getPersistenceManager();
pm.currentTransaction().begin();
try
{
StringBuilder sb = new StringBuilder();
sb.append("select from ");
sb.append(SerialTest2.class.getName());
sb.append(" where key == 'A123'");
st2List = (List<SerialTest2>) pm.newQuery(sb.toString
()).execute();
if (st2List == null || st2List.size() < 1)
{
log.info("No existing record found");
SerialTest2 st2 = new SerialTest2();
st2.setKey("A123");
st2.setTestString("First Test String");
pm.makePersistent(st2);
}
else
{
log.info("Found existing record");
log.info("--testString: " + st2List.get
(0).getTestString());
ArrayList<String> testStrings = st2List.get
(0).getTestStrings();
for (String s: testStrings)
{
log.info("--testStrings: " + s);
}
st2List.get(0).setTestString("Second Test String");
log.info("Updated record ready to persist");
log.info("--testString: " + st2List.get
(0).getTestString());
testStrings = st2List.get(0).getTestStrings();
for (String s: testStrings)
{
log.info("--testStrings: " + s);
}
pm.makePersistentAll(st2List);
}
pm.currentTransaction().commit();
}
catch (javax.jdo.JDOObjectNotFoundException e)
{
log.info("Threw JDOObjectNotFoundException");
}
catch (Exception e)
{
StringWriter sw = new StringWriter();
e.printStackTrace(new PrintWriter(sw));
log.severe("Error during insert/update step: " +
sw.toString());
}
finally
{
if (pm.currentTransaction().isActive())
{
pm.currentTransaction().rollback();
}
pm.close();
}
log.info("Query
--------------------------------------------");
pm = PMF.get().getPersistenceManager();
try
{
StringBuilder sb = new StringBuilder();
sb.append("select from ");
sb.append(SerialTest2.class.getName());
sb.append(" where key == 'A123'");
st2List = (List<SerialTest2>) pm.newQuery(sb.toString
()).execute();
if (st2List == null || st2List.size() < 1)
{
log.info("No existing record found");
}
else
{
log.info("Found existing record");
log.info("--testString: " + st2List.get
(0).getTestString());
ArrayList<String> testStrings = st2List.get
(0).getTestStrings();
for (String s: testStrings)
{
log.info("--testStrings: " + s);
}
}
}
catch (javax.jdo.JDOObjectNotFoundException e)
{
log.info("Threw JDOObjectNotFoundException");
}
catch (Exception e)
{
StringWriter sw = new StringWriter();
e.printStackTrace(new PrintWriter(sw));
log.severe("Error during query step: " + sw.toString());
}
finally
{
pm.close();
}
First run (when it creates a new datastore entity):
INFO: Insert/Update ------------------------------------
INFO: No existing record found
INFO: Query --------------------------------------------
INFO: Found existing record
INFO: --testString: First Test String
INFO: --testStrings: First Test String
Second run (when it updates the entity):
INFO: Insert/Update ------------------------------------
INFO: Found existing record
INFO: --testString: First Test String
INFO: --testStrings: First Test String
INFO: Updated record ready to persist
INFO: --testString: Second Test String
INFO: --testStrings: First Test String
INFO: --testStrings: Second Test String
INFO: Query --------------------------------------------
INFO: Found existing record
INFO: --testString: Second Test String
INFO: --testStrings: First Test String
Note that the query returned an entity with "testString" updated, but
"testStrings" still contains only one item--in other words it was not
updated.
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