Joomla 1.5 - JTable queries always doing UPDATE instead of INSERT - joomla

Question

The following code is straight from the docs and should insert a row into the "test" table.
$row = &JTable::getInstance('test', 'Table');
if (!$row->bind( array('user_id'=>123, 'customer_id'=>1234) )) {
return JError::raiseWarning( 500, $row->getError() );
}
if (!$row->store()) {
JError::raiseError(500, $row->getError() );
}
My table class looks like this:
class TableTest extends JTable
{
var $user_id = null;
var $customer_id = null;
function __construct(&$db)
{
parent::__construct( '#__ipwatch', 'user_id', $db );
}
}
SELECT queries work fine, but not INSERT ones. Through debugging I find that the query being executed is UPDATE jos_test SET customer_id='1234' WHERE user_id='123', which fails because the row doesn't exist yet in the database (should INSERT instead of UPDATE).
While digging through the Joomla code I find this:
function __construct( $table, $key, &$db )
{
$this->_tbl = $table;
$this->_tbl_key = $key;
$this->_db =& $db;
}
.....
.....
function store( $updateNulls=false )
{
$k = $this->_tbl_key;
if( $this->$k)
{
$ret = $this->_db->updateObject( $this->_tbl, $this, $this->_tbl_key, $updateNulls );
}
else
{
$ret = $this->_db->insertObject( $this->_tbl, $this, $this->_tbl_key );
}
if( !$ret )
{
$this->setError(get_class( $this ).'::store failed - '.$this->_db->getErrorMsg());
return false;
}
else
{
return true;
}
}
_tbl_key here is "user_id" that I passed in my TableTest class, so it would appear that it will always call updateObject() when this key is set. Which is baffling.
Anyone have any insight?

Answer 1

function store( $updateNulls=false )
{
// You set user_id so this branch is executed
if( $this->$k)
{
$ret = $this->_db->updateObject( $this->_tbl, $this, $this->_tbl_key, $updateNulls );
}
// ...
Looking at the code it seems to me that store() check if the primary key field is present and if it use updateObject(). This means if you want to store a new user you can't specify the user_id.