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Re: Prototypes and Inheritance
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Re: Prototypes and Inheritance

  • Subject: Re: Prototypes and Inheritance
  • From: Mike Schrag <email@hidden>
  • Date: Fri, 26 Aug 2005 08:49:08 -0400
When I've gotten weird NPE's from a query, it's almost always been a bug w/ prototypes where EOModeler blanked out one of the fields on an attribute definition.  Specifically in this case look for a value class that is blank that's not supposed to be.  If you're running w/ eclipse, you can turn on the flag that breakpoints any time an exception is thrown and trace in and see the actual attribute name that it's trying to set -- that might be your fastest way of tracking this problem down.

The other time I've gotten really strange NPE's like this is when I switched the definition of my boolean fields, but EOModeler didn't remove the old references to factory methods and adaptorValueConversionMethodNames.  So search in your prototypes and your eomodel plist files for "adaptorValueConversionMethodName" and make sure what you see in the .plist file matches what you actually meant the definition to be (probably you will find this in your EOJDBCPrototypes.plist file).

Basically the error you're seeing should never happen, so it's almost certainly a malformed model.

ms

On Aug 25, 2005, at 10:55 PM, Alex Horovitz wrote:


On Aug 25, 2005, at 7:16 PM, Dev WO wrote:

The application starts with a loggin panel, I enter an email and a password which are in the database (from when the application was working) and got:
----
[2005-08-26 01:02:55 CEST] <WorkerThread1> java.lang.NullPointerException
    at com.webobjects.eoaccess.EOAttribute.adaptorValueByConvertingAttributeValue(EOAttribute.java:2020)
    at com.webobjects.jdbcadaptor.JDBCColumn.takeInputValue(JDBCColumn.java:562)
    at com.webobjects.jdbcadaptor.JDBCChannel._bindInputVariablesWithBindingsAndExecute(JDBCChannel.java:226)
    at com.webobjects.jdbcadaptor.JDBCChannel._evaluateExpression(JDBCChannel.java:303)
    at com.webobjects.jdbcadaptor.JDBCChannel.evaluateExpression(JDBCChannel.java:261)
    at com.webobjects.jdbcadaptor.JDBCChannel.selectAttributes(JDBCChannel.java:185)
    at com.webobjects.eoaccess.EODatabaseChannel._selectWithFetchSpecificationEditingContext(EODatabaseChannel.java:878)
    at com.webobjects.eoaccess.EODatabaseChannel.selectObjectsWithFetchSpecification(EODatabaseChannel.java:215)
    at com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEditingContext(EODatabaseContext.java:3205)
    at com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(EODatabaseContext.java:3346)
    at com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:539)
    at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4111)
    at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4497)
    at Session.validateMember(Session.java:105)
----
then the sql evaluation a couple lines below
----
[2005-08-26 01:02:55 CEST] <WorkerThread1>  === Begin Internal Transaction
[2005-08-26 01:02:55 CEST] <WorkerThread1>  evaluateExpression: <com.webobjects.jdbcadaptor.MySQLPlugIn$MySQLExpression: "SELECT t0.C_MEMBER_ADMIN_RIGHTS, t0.C_MEMBER_MANAGING_ITEMS_RIGHTS, t0.C_MEMBER_MANAGING_LINKS_RIGHTS, t0.C_MEMBER_MANAGING_TEXT_RIGHTS, t0.C_PERSON_ACTIVATION, t0.C_PERSON_EMAIL, t0.C_PERSON_FIRST_NAME, t0.C_PERSON_PERSON_ID, t0.C_PERSON_LAST_NAME, t0.C_PERSON_PASSWORD, t0.C_PERSON_REGISTRATION_DATE FROM MEMBER t0 WHERE t0.C_PERSON_EMAIL = ?" withBindings: 1:"email@hidden"(personEmail)>

----
and finally the line which lead to the crash in my application:
----
        if (password == null || password == "") return false;
        if (email == null || email == "") return false;
        NSMutableArray args = new NSMutableArray();
        args.addObject(email);
        EOQualifier qual = EOQualifier.qualifierWithQualifierFormat("personEmail = %@", args);
        EOFetchSpecification spec = new EOFetchSpecification("Member",qual,null);
        NSArray results = ec.objectsWithFetchSpecification(spec); //THIS is the line
----
So it looks like it doesn't find any entry in the database for this email?!


I know these should be morally equivalent, but, have you tried constructing your qualifier as follows:

EOKeyValueQualifier qual = new EOKeyValueQualifier("personEmail", EOQualifier.QualifierOperatorEqual, email);

also, you probably want to do this in case the user just registered...

spec.setRefreshesRefetchedObjects(true);

and, when you are actually talking to the database, if this is all happening outside a try catch you might want to be in a try catch ala          

NSArray results = null;

try {
    results = ec.objectsWithFetchSpecification(spec);
} catch (Exception e) {
    e.printStackTrace();
}

this way, if something strange happens when you are talking to the database, you don't bring everything crashing down around you...

Good luck!

Alex



--
Alex Horovitz
CTO | VP Engineering

The Brookeside Group, Inc.

"The 20th century will be chiefly remembered by future generations not as an era of political conflicts or technical inventions, but as an age in which human society dared to think of the welfare of the whole human race as a practical objective."

Arnold Toynbee (1889-1975)
English Historian


<ahorovit.vcf>



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  • Follow-Ups:
    • Re: Prototypes and Inheritance
      • From: Dev WO <email@hidden>
References: 
 >Prototypes and Inheritance (From: Dev WO <email@hidden>)
 >Re: Prototypes and Inheritance (From: Chuck Hill <email@hidden>)
 >Re: Prototypes and Inheritance (From: Dev WO <email@hidden>)

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