[Rdfapi-php-interest] some problems with the replace function (DbModel.php)

[<van...@ce...>]

Hello,

I have some questions concerning the function replace from the DbModel.php.

First of all, I don't understand the conditions when the script checks 
the correctness of the passed params in particular the lines 666 to 668. 
I don't understand  why the replacement param could not be a Literal or 
a blanknode when the subject or the predicate is not null. Can you give 
me some precisions?

Secondly, I don't understand why we set the subject or the predicate in 
the sql query. (lines 680 to 688)  If I understand the goal of the 
function, we can change only the object. So, why we should set also the 
subject or the predicate? In addition, when the function changes the 
subject or the predicate, it changes with the replacement value. I think 
it's not the normal behaviour. In my script, this function changes the 
subject, the predicate and the object with the same value, the 
replacement param.

Finally, at line 689, why is there a condition of the object. In this 
case, we have to put the old object in param. The old object can't be 
null. Why?

I need this functions to update some statements of  my database.
For the moment, the original function don't allow me to change the 
object of the statement when I give the subject and the predicate.
I have modified the function for my needs and for me the function should 
look like this one:

    function replace($subject, $predicate, $object, $replacement) {

        // check the correctness of the passed parameters
        if ( ((!is_a($subject, 'Resource') && $subject != NULL) ||
        (!is_a($predicate, 'Resource') && $predicate != NULL) ||
        (!is_a($object, 'Node') && $object != NULL)))
        {
            $errmsg = RDFAPI_ERROR . '(class: DbModel; method: find): 
Parameter mismatch';
            trigger_error($errmsg, E_USER_ERROR);
        }

        if (!(!$subject && !$predicate && !$object)) {

            // create an update sql statement
            $comma = '';
            $sql = 'UPDATE statements
             SET ';
           
            $quotedObject = $this->dbConn->qstr($replacement->getLabel());
            $sql .= $comma .' object=' .$quotedObject
             .", object_is='" .$this->_getNodeFlag($replacement) ."' ";
            if (is_a($replacement, 'Literal')) {
            $sql .= ", l_language='" .$replacement->getLanguage() ."' "
            .", l_datatype='" .$replacement->getDataType() ."' ";
            }

            $sql .= 'WHERE modelID = ' .$this->modelID;
            $sql .= $this->_createDynSqlPart_SPO($subject, $predicate, 
$object);

            // execute the query
            $rs =& $this->dbConn->execute($sql);

            if (!$rs)
            echo $this->dbConn->errorMsg();
        }
    }

I'm waiting your feedbacks...   :-)

regards,

Aurélien Van Hamme