Re: Help with NPE in EOCustomObject.willReadRelationship()
Re: Help with NPE in EOCustomObject.willReadRelationship()
- Subject: Re: Help with NPE in EOCustomObject.willReadRelationship()
- From: Chuck Hill <email@hidden>
- Date: Tue, 28 Apr 2009 21:40:23 -0700
Hi Peter,
On Apr 28, 2009, at 9:20 PM, Peter Vandoros wrote:
Hi All,
I have an issue where a NullPointerException is thrown within
EOCustomObject.willReadRelationship(). Before I log a radar, I want
to see if anyone else has had a similar issue and if so, what you
did to resolve it.
I believe the issue is that EOCustomObject.willReadRelationship() is
called firing a fault on a deleted EO. The only way that
EOCustomObject.willReadRelationship() will throw a NPE is if
editingContext() returns null and 'object' is a fault (ie.
EOFaultHandler.isFault(object) returns true).
What am I doing to cause this sequence of events you ask? it's
relatively simple:
- I have a class
(path.to.class.listening.to.editingcontext.notification.MyClass from
stack trace below) that listens to
EOEditingContext.EditingContextDidSaveChangesNotification
notifications and does some processing.
- The NPE occurs in a debug statement that prints the NSNotification
object passed to my MyClass.editingContextDidSaveChanges() method
before any processing occurs.
That is not going to have happy results...
- I tracked down the culprits to be 3 of 10 deleted objects in the
NSNotification's "deleted" userInfo key value, throwing NPE's in
their EOCustomObject.toString() method.
See! :-) Yes, you should not do anything to a deleted object. It
makes EOF rather cross.
Obviously deleted EO's shouldn't have editingContext()'s, but I
believe that EOCustomObject.eoDescription() should not fire _any_
faults
I don't think that I would agree with that. The information from
firing faults can be very useful. You can certainly re-implement it
to not fire the faults or output something very limited if
editingContext() == null. That is a reasonable suggestion to make in
a bug report.
or EOCustomObject.willReadRelationship() should check to see if
editingContext() is null when 'object' is a fault.
And throw an exception. That is a reasonable suggestion to make in a
bug report.
I can override EOCustomObject.willReadRelationship() in my super
class and return null when "editingContext() == null &&
EOFaultHandler.isFault(object)", but I want to know what other
potential issues this will cause.
That would make me nervous. If this method is called when
editingContext() == null, that indicates to me a coding mistake. An
exception seems appropriate and the NPE is not exactly helpful.
Chuck
Model:
Entity1 ----> Entity2 <<----> Entity3
- There are 3 similar relationships between Entity2 & Entity3 (used
for different purposes)
Stacktrace:
java.lang.NullPointerException
at
com
.webobjects
.eocontrol.EOCustomObject.willReadRelationship(EOCustomObject.java:
1293)
at com.webobjects.eocontrol._EOMutableKnownKeyDictionary$Initializer
$
_LazyGenericRecordBinding
.valueInObject(_EOMutableKnownKeyDictionary.java:560)
at
com
.webobjects
.eocontrol.EOCustomObject.storedValueForKey(EOCustomObject.java:1736)
at
path
.to
.my.eo.class._Entity3.myToManyRelationshipToEntity2(_AnEntity.java:
492)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun
.reflect
.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun
.reflect
.DelegatingMethodAccessorImpl
.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.webobjects.foundation.NSKeyValueCoding$ValueAccessor
$1.methodValue(NSKeyValueCoding.java:684)
at com.webobjects.foundation.NSKeyValueCoding
$_MethodBinding.valueInObject(NSKeyValueCoding.java:1160)
at
com
.webobjects.eocontrol.EOCustomObject.valueForKey(EOCustomObject.java:
1559)
at
com
.webobjects
.eocontrol.EOCustomObject.eoDescription(EOCustomObject.java:793)
at
com.webobjects.eocontrol.EOCustomObject.toString(EOCustomObject.java:
239)
at com.webobjects.foundation.NSArray.toString(NSArray.java:920)
at java.lang.String.valueOf(String.java:2827)
at java.lang.StringBuffer.append(StringBuffer.java:219)
at
com.webobjects.foundation.NSDictionary.toString(NSDictionary.java:541)
at java.lang.String.valueOf(String.java:2827)
at java.lang.StringBuffer.append(StringBuffer.java:219)
at
com
.webobjects.foundation.NSNotification.toString(NSNotification.java:
175)
at
path
.to
.class
.listening
.to
.editingcontext
.notification
.MyClass.editingContextDidSaveChanges(EOCacheChangeCollector.java:141)
Regards
Peter Vandoros
Software Engineer
Etech Group Pty Ltd
Level 3/21 Victoria St
Melbourne VIC 3000
Australia
Ph: +61 3 9639 9677
Fax: +61 3 9639 9577
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--
Chuck Hill Senior Consultant / VP Development
Come to WOWODC'09 in San Fran this June!
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