Hacking application id equals() to allow more than one row per "primary key"

Question

I have a read only entity whose primary key is not the real primary key
on the underlying table. The result is that I get more than one row per
"primary key". This is what I want. However KODO will not allow me do
it, because I am storing the collection in a HashSet() and the equals()
method on the application id object ensures that this set contains no
duplicates (as defined by the application id). At least thats how it
seems to behave.
So, I have hacked the equals() method to do this:
public boolean equals (Object ob)
if (this == ob)
return true;
// Doing this because we expect more than one row from
// REF_CODES for the same domain/shortCode combination.
// This is ok to do (I guess?) as long as we are only
// doing selects using this class.
return false;
Will this hack have any side effects? Is there another option? Like
using a list collection? Is so, which collections are supported?
Thanks,
Mike.

Answer 1

The "primary key" I am using it already a compound key of two columns.
The real key on the underlying table is a three column key. But the
problem is that the table represents two different application level
entities. I could deal with it when I was hand-writing SQL (I could do
a distinct for example) but now I am relying on foreign key
relationships since I moved to JDO. Not sure what to do. Best solution
is to rework the table, but there is a lot of legacy code (that other
teams use and maintain) relying on this table. I guess I'll use the
weekend for inspiration ;-)
Steve Kim wrote:
This sounds like a dangerous operation. Even if this works now, I
cannot promise future compatibility... and in fact may result in bad
data (for example in caching both at the PM and PMF level) Is there no
other field that you can reference as part of the primary key? Primary
Keys can be multi columned (e.g. last_name, soc_sec_number)
Mike Hogan wrote:
I have a read only entity whose primary key is not the real primary
key on the underlying table. The result is that I get more than one
row per "primary key". This is what I want. However KODO will not
allow me do it, because I am storing the collection in a HashSet() and
the equals() method on the application id object ensures that this set
contains no duplicates (as defined by the application id). At least
thats how it seems to behave.
So, I have hacked the equals() method to do this:
public boolean equals (Object ob)
if (this == ob)
return true;
// Doing this because we expect more than one row from
// REF_CODES for the same domain/shortCode combination.
// This is ok to do (I guess?) as long as we are only
// doing selects using this class.
return false;
Will this hack have any side effects? Is there another option? Like
using a list collection? Is so, which collections are supported?
Thanks,
Mike.