Updating part of a composite key

I have a table 'broadcast', with a foreign key 'pid' to a table
'version',
and with primary key a composite of 'pid' and 'imi', i.e.:

  broadcast:                              version:

     pid  } broadcast  ----------->         pid  } version
     imi  }  key 0                                  key 0
       :::                                   :::

I want to write a test script that uses DBIx::Class to set up some
records, represented by $broadcast, $version_1, and $version_2,
such that initially $broadcast links to $version_1 and then is
changed by the following to link to $broadcast_2:

  $broadcast->version($version_2);

However, when I run the test it displays the following error
(referring to the line containing this call):

  Can't update Broadcast=HASH(0x2d72c14): row not found at
t/unit/misc/hack.t

The SQL log showed that this call led to the following SQL:

  UPDATE broadcast SET pid = ?
   WHERE ( imi = ? AND pid = ? ): `pidhack_2', `imix002', `pidhack_2' 

In other words, it is using the required new key value in the WHERE
clause,
instead of the current key value i.e. obviously _should_ be (in this
case):

  UPDATE broadcast SET pid = ?
   WHERE ( imi = ? AND pid = ? ): `pidhack_2', `imix002', `pidhack_1' 

Is there likely to be a problem with DBIx::Class updating parts of
composite
Keys using the above?

Impressive though it is, I realize DBIx::Class it can't be infallible,
and
maybe in this situation it needs things spelled out more explicitly.

If so, can anyone suggest an alternative format for the above call,
or some extra information I need to include in the schema definition?

Thanks in advance.


Cheers

John R Ramsden

http://www.bbc.co.uk/
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