[appengine-java] GWT+JDO+GAE enhancement nightmare

[John Howe]

Using JDO, I persist without error an object containing List of String
elements. However, when I read back the object, I get this multi-part
error indicating that the object just persisted without error is not
persistable. If there was a problem persisting the object, it would
have been nice to get an exception when it was persisted. So, if I
think List is enhanced, then what?

I've seen many related posts on this, and the advice ranged from "the
solution is in the error message [you dummy]" to "this must be GWT
related" to "enhancing ArrayList doesn't work, so you are
expected to read each member as org.datanucleus.sco.backed.ArrayList."

This seems pretty basic. Can somebody wake me from this nightmare?


SEVERE: [1269227590728000] javax.servlet.ServletContext log: Exception
while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method
'public abstract java.util.List
com.sportzcasteralpha2a.myproject.client.
mvc.Service.boxDataFetch(java.util.List)' threw an unexpected
exception:
org.datanucleus.jdo.exceptions.ClassNotPersistenceCapableException:
 The class "The class "java.util.ArrayList" is not persistable. This
means that it either hasnt been enhanced, or that the enhanced
version
of the file is not in the CLASSPATH (or is hidden by an unenhanced
version), or the Meta-Data/annotations for the class are not found."
is n
ot persistable. This means that it either hasnt been enhanced, or that
the enhanced version of the file is not in the CLASSPATH (or is hidde
n by an unenhanced version), or the Meta-Data for the class is not
found.
NestedThrowables:
org.datanucleus.exceptions.ClassNotPersistableException: The class
"java.util.ArrayList" is not persistable. This means that it either
hasnt
 been enhanced, or that the enhanced version of the file is not in the
CLASSPATH (or is hidden by an unenhanced version), or the Meta-Data/a
nnotations for the class are not found.

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Re: [appengine-java] GWT+JDO+GAE enhancement nightmare

[Shawn Brown]

> This seems pretty basic. Can somebody wake me from this nightmare?

Sorry, been there...

If I was starting over, I'd seriously think about:

http://code.google.com/p/objectify-appengine/

for two reasons:

1) Objectify entities can be used in GWT without the need for Data
Transfer Objects.
2) it seems cold start up time is better when you take the jdo and
datanucleus stuff out. (judging by mail on this list)

There are much more knowledgeable people on this list but ... yeah I
know it's a nightmare to get it figured out in the beginning and don't
wonder if objectify isn't simpler.

Shawn

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Re: [appengine-java] GWT+JDO+GAE enhancement nightmare

[John Patterson]

On 22 Mar 2010, at 13:20, Shawn Brown wrote:


1) Objectify entities can be used in GWT without the need for Data
Transfer Objects.


Twig data models also have this property but with the advantage that  
they have no dependencies on the low-level datastore - just pure  
unrestricted pojos.



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