Re: [Objectbridge-developers] A few problems

[Thomas M. <tho...@ho...>]

Hi Kief,

Kief Morris wrote:
> 
> Howdy, I've been banging on some code, and so far ojb is pretty cool,
> but I've run into a few things.
> 
> 1) Dates: I had some issues storing fields of type java.util.Date, which
>     may or may not be specific to the mySQL JDBC driver. I notice the
>     example application doesn't use and date/time fields, has this been
>     tested much with other drivers?
> 
>     The issue is that ojb uses PreparedStatement.setObject(int parameterIndex, Object x)
>     to store fields, and the mySQL driver at least doesn't automatically figure
>     out what type this is: the result is it stores 0 as the date/time value.
>     Using setObject(index, myDate, java.sql.Types.TIMESTAMP) works,
>     as does wrapping the Date object with java.sql.Timestamp, which is
>     the workaround I've used in my code.
> 

We have similar problems with other drivers too! The Oracle driver for
example returns all Number columns as BigDecimal even if the Objects
attribute is only a int.

We will have to improve this behaviour!
For the time being you might work with a ConversionStrategy that makes
an explicit TypeConversion before reading and writing from JDBC
ResultSets. See the tutorial on this topic:
http://objectbridge.sourceforge.net/conversions.html

> 2) ObjectCache doesn't appear to retrieve referenced objects. When I
>     store and then retrieve an object which references a collection, the
>     retrieved object doesn't have the collection items. If I insert:
> 
>         ojb.broker.accesslayer.ObjectCache.getInstance().clear();
> 
>     - between the store and the find, the retrieved object *does* have
>     the collection. I don't totally understand this - presumably the cache
>     should return the same object, including its references, but a comparison
>     of the two objects without the above call shows one has the collection,
>     the other's collection is empty.
> 

You are right, store does not cache the object. That's why a different
object reference is returned by getObjectByQuery(...)
There was no special reason for this, but I guess I will change it,
because the semantics is really a bit funny due to this asymmetry...

I have no idea why your Collection is not filled. This is a thing that
MUST work!
You might send me your source code (only the relevant stuff) and your
repository.xml file to check what's wrong.


regards,

Thomas


> Thanks,
> Kief
> 
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