Object ID reference

Hi I'm new to the list, and I'm new to the PostgreSQL also. But I have been using Object Relation Mapping for a period of time. I would like to put native binding with PostgreSQL . It is fairly easy to read and write Object into the relayed table e.g.

create table base (
myname text,
unique( myname )
);

create table child (
myfather base,
myname text
);

INSERT INTO base ( myname ) Values ( 'alex' ) ;
INSERT 56578 1 <<---- oid
INSERT INTO child ( myfather, myname ) values ( 56578::base, 'alexbaby' );
INSERT 56579 1 <<---- oid

However, there is no way to get the value back in the WHERE clause. because the return type is 'base' but the value output ( correct me if I'm wrong from digging the source by hand ) is actually oid returns int4 from internal seteval() function.
select * from child;
myfather myname
-------------------
56578 alexbaby

It could be a easy fix in the jdbc, or c to match the seteval(base.oid) with int4.[string, string] compare, but then I need to loop through the full Record Set by hand to get the data. is there a possible way to do some function to convert the TYPE 'base' to oid or int4 or string?
so I can do something like this

SELECT * from child where myfather=56578::base;

or how am I getting internal seteval to work right with the return set from a custom function.
I really want to see this coming out right... thanks a lot.
Alex