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Re: valueForKey(...) from within takeStoredValueForKey(...) = infinite loop
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Re: valueForKey(...) from within takeStoredValueForKey(...) = infinite loop


  • Subject: Re: valueForKey(...) from within takeStoredValueForKey(...) = infinite loop
  • From: Fabian Peters <email@hidden>
  • Date: Wed, 16 Jan 2008 20:31:28 +0100

Hi Florijan,

Am 16.01.2008 um 20:20 schrieb Florijan Stamenkovic:

Hi all,


I've been trying to override some EOCustomObject methods to perform event firing. However, I bumped into a problem when the objects are first being initialized with values. The thing is, i use the old value in the fired event. This meant my takeStoredValue method looks like this:



public void takeStoredValueForKey(Object object, String key){ Object oldValue = FIRE_EVENTS ? valueForKey(key) : null; super.takeStoredValueForKey(object, key); if(FIRE_EVENTS) fireDataObjectEvent(key, oldValue); }


However, during the first initialization of the EO the first line of the method (getting of the old value) triggers a fault to fire, which triggers EOF to get the value and set it on the EO using the takeStoredValueForKey(..) method. Which ends up in an infinite loop. Bummer.

I've been down that road as well. storedValueForKey is used behind the scenes by EOF. I ended up putting a method in a common superclass:


public void willChange(Object oldValue, Object newValue, String key) {
// to be used by subclasses
}


And then placing this in the setters created by EOGenerator:

willChange(storedValueForKey("theKey"), value, "theKey");



When I need this fine-grained change tracking on an EO, I fill in the willChange() method.

HTH,

Fabian


What I've tried is printing a stack trace of an exception as the first line in the takeStoredValueForKey(..) method, hoping to find out which method was calling it. Then I'd override that method, to skip event firing during the initialization (by setting the FIRE_EVENTS flag to false during it's duration). But, the stack trace does not imply any method in which I could do that (I edited out all the trace elements that are not from com.webobjects...):


java.lang.Exception
at org .jbnd .eof .FiringEOFDataObject.takeStoredValueForKey(FiringEOFDataObject.java: 102)
at com .webobjects .eodistribution .client .EODistributedObjectStore .initializeObject(EODistributedObjectStore.java:249)
at com .webobjects .eocontrol.EOEditingContext.initializeObject(EOEditingContext.java: 3805)
at com .webobjects .eodistribution .client .EODistributedObjectStore._fireFault(EODistributedObjectStore.java: 1129)
at com .webobjects .eodistribution .client .EODistributedObjectStore .initializeReplacementObject(EODistributedObjectStore.java:814)
at com .webobjects .eodistribution .client .EODistributedObjectStore ._replacementObjectForDecodedObject(EODistributedObjectStore.java:788)
at com .webobjects.foundation.NSSelector._safeInvokeMethod(NSSelector.java: 120)
at com.webobjects.foundation._NSDelegate._perform(_NSDelegate.java: 225)
at com.webobjects.foundation._NSDelegate.perform(_NSDelegate.java: 162)
at com .webobjects .eodistribution .common ._EOReferenceRecordingCoder .decodeObject(_EOReferenceRecordingCoder.java:559)
at com .webobjects .eodistribution .common ._EOReferenceRecordingCoder .decodeObjects(_EOReferenceRecordingCoder.java:587)
at com.webobjects.foundation.NSArray.decodeObject(NSArray.java:1309)
at com.webobjects.eodistribution.common._EOReferenceRecordingCoder $_Decoder.decodeObject(_EOReferenceRecordingCoder.java:704)
at com .webobjects .eodistribution .common ._EOReferenceRecordingCoder .decodeObject(_EOReferenceRecordingCoder.java:551)
at com .webobjects .eodistribution .common._EOServerReturnValue.decodeObject(_EOServerReturnValue.java: 62)
at com.webobjects.eodistribution.common._EOReferenceRecordingCoder $_Decoder.decodeObject(_EOReferenceRecordingCoder.java:704)
at com .webobjects .eodistribution .common ._EOReferenceRecordingCoder .decodeObject(_EOReferenceRecordingCoder.java:551)
at com .webobjects .eodistribution .common ._EOReferenceRecordingCoder .decodeObjects(_EOReferenceRecordingCoder.java:587)
at com.webobjects.foundation.NSArray.decodeObject(NSArray.java:1309)
at com.webobjects.eodistribution.common._EOReferenceRecordingCoder $_Decoder.decodeObject(_EOReferenceRecordingCoder.java:704)
at com .webobjects .eodistribution .common ._EOReferenceRecordingCoder .decodeObject(_EOReferenceRecordingCoder.java:551)
at com .webobjects .eodistribution .client.EOHTTPChannel._responseToMessage(EOHTTPChannel.java:533)
at com .webobjects .eodistribution .client.EOHTTPChannel.responseToMessage(EOHTTPChannel.java:603)
at com .webobjects .eodistribution .client.EODistributedObjectStore._send(EODistributedObjectStore.java: 594)
at com .webobjects .eodistribution .client.EODistributedObjectStore._send(EODistributedObjectStore.java: 623)
at com .webobjects .eodistribution .client .EODistributedObjectStore .objectsWithFetchSpecification(EODistributedObjectStore.java:506)
at com .webobjects .eocontrol .EOEditingContext .objectsWithFetchSpecification(EOEditingContext.java:4114)
at com .webobjects .eocontrol .EOEditingContext .objectsWithFetchSpecification(EOEditingContext.java:4500)


Anyone has any idea how I could do this? If not, I am stuck with events being fired only in value setters.

Thx
Flor
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