Re: Problem with reading records having a PK with value 0 (not null)

[Danilo Tommasina]

Hi Armin,

here a short example.

create TABLE FOO ( TAB_ID INTEGER PRIMARY KEY )
and put an entry into the table with ID = 0 (from SQL not from OJB)
/*****/
repoistory.xml
<class-descriptor class="org.apache.ojb.test.Foo" table="FOO" >

    <field-descriptor name="tabId" column="TAB_ID" jdbc-type="DECIMAL" 
            nullable="false" primarykey="true" autoincrement="true" />

<class-descriptor/>

/****/
public class Foo {
    public Integer tabId;

//Add getter and setter

}



/****/
some test code
(...)
Criteria c = new Criteria();
c.addEqualTo( "tabId", new Integer( 0 ) );
Query q = new QueryByCriteria( Foo.class, c );
Foo myFoo = (Foo) pb.getObjectByQuery( q );

pb.beginTransaction();
pb.store( myFoo );
pb.commitTransaction();
(...)
and now you have two entries in your database (Integer PK with value 0 
was interpreded as null and a new clone has been inserted)

This is actually a minor issue, since it is not possible through OJB to 
add a DB entry with a PK = 0, in this case the error will never occur.
However if you are using data inserted by other applications it is 
possible to have entries with ID = 0 to work with.

sorry I didn't tested the code, I hope it works...

bye
Danilo

Hi Danilo,

Danilo Tommasina wrote:

Hi,

I reported the same issue some months ago...
The problem lies in the support for primitive data types, since a 
primitive type cannot be null, the value 0 is interpreted as null.
It seems that non primitive data types also react the same way (even 
if they shouldn't, so from my point of view it is a bug)


if so, I agree sounds like a bug. Can you post a test case to reproduce 
the problem or describe what to do with pseudo code?

Fetching an object with ID = 0 works, however OJB will handle the 0 
value as null and put the next sequence value into the fetched object 
on next store or when calling a 
PeristenceBroker.retrieveAllReferencies( Object obj )


For OJB 1.1 a complete refactoring of the primitive data types handling 
is scheduled.
Here you can post your proposals for the upcoming 1.1 version

http://nagoya.apache.org/wiki/apachewiki.cgi?OJBProjectPages/OJBOnePointOne



The workaround is to never use IDs = 0 and this is actually what I am 
doing ;)


or don't use primitive data types for PK fields in your pc objects (or 
do both ;-)).

regards,
Armin
bye
Danilo
Hi,

 

It looks like OJB cannot fetch correctly records which have a BigInt 
primary
key with value 0; at least in the following conditions;

 

- I'm using RC5

- Have a table (here Locations) with a primary key Id with a 
auto-increment
sequence

- I'm using Oracle 9.2

- The table has a 1-N collection using a proxy.

 

 

For instance, I have the following mapping:

 

                <class-descriptor class="Locations" table="LOCATIONS">

 

            <field-descriptor name="id" column="ID"
jdbc-type="BIGINT" primarykey="true"
autoincrement="true"
sequence-name="locations_id_seq"/>
 

            <field-descriptor name="latitude" column="LATITUDE"
jdbc-type="BIGINT"/>
 

            <field-descriptor name="longitude" column="LONGITUDE"
jdbc-type="BIGINT"/>
            ...

            <collection-descriptor name="collElements"
element-class-ref="Elements" proxy="true">
                  <inverse-foreignkey field-ref="locationid"/>

            </collection-descriptor>

 

      </class-descriptor>

 

 

Now in the database, there is a location with Id=0.

When I use OJB to fetch this record (with a criteria on Id=0), the 
resulting
instance is correct except for the Id field which has the next sequence
value.

 

Tracing the code, what happens is when the query is executed:

 

-          RsIterator.getObjectFromResultSet reteive the simple fields
correctly
-          As there is a collection, retrieveCollections is called

-          The query to retrieve the collection is built: Query 
fkQuery =
getFKQuery(obj, cld, cds);
-          This retrieves the PK fields values (getFKQuery1toN ) which
indirectly calls getValuesForObject
-          When the value for the Id is retrieved 
(getAutoIncrementValue),
it is considered as Null (BrokerHelper.isNull) and thus the sequence is
called.

 

Can this be considered a bug?

Are there any workarounds?

 

 

Thanks,

 

-Alex

 




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