Call to undefined method stdClass - php

Question

I am occasionally getting the PHP Fatal error: Call to undefined method stdClass::transition() in agent.php on line 25 (I marked line 25 in the code). This code is called often, so struggling to see why it is happening.
Here is the snippet of agent.php that calls the
function agent_exam_complete($exam){
$ce = $exam->educational();
$ce->exam_id = $exam->exam_id;
$ce->exam_grade = $exam->score;
$ce->exams_remaining -= 1;
$ce->exam_received_date = sql_now();
if($exam->status()=='passed'){
$ce->transition('passed');
}elseif($ce->exams_remaining <= 0){
$ce->transition('failed');
}
$ce->save();
if($ce->is_certification_completed($ce->certification_id, $ce->client_no)){
agent_certification_complete($ce->certification_id, $ce->client_no);
}
}
function agent_certification_complete($certification_id, $client_no){
$ce = ClientPurchase::find('first', array('conditions' => "certification_id = '$certification_id' and is_certification = 1 and client_no='$client_no'"));
$ce->certification_date = date('Y-m-d');
$ce->transition('passed'); **//Line 25**
$ce->save();
}
transition() is defined in another file and is called often. I've included a little bit of it's code just for flavor.
function transition($event_tag){
$old_status = $this->status;
$next_status = $this->next_status_for_transition($event_tag);
if($next_status==''){
return; }
$this->status = $next_status;
My question is, why am I only getting this error periodically and not all the time? What can I do to eliminate the error and subsequent blank screen for my clients? I've only noticed that it is happening to those with Firefox or Chrome.
Thanks in advance,
Jim

Answer 1

The object $ce that contains the function is being generated multiple times. I suppose this is so transition is customized for whatever object is called.
Why not create another object for re-useable functions? Consider expanding the function so that it is compatible with all objects that would use it.
$my = new functionClass;
class functionClass
{
function transition()
{
$old_status = $this->status;
$next_status = $this->next_status_for_transition($event_tag);
if($next_status==''){
return; }
$this->status = $next_status;
}
}
$my->transition( 'passed' );
Something like that would cut down on unpredictability and I believe may solve your problem.

Answer 2

Try this little snippet of code to see whats going on:
$ce = false;
$ce->certification_date = date('Y-m-d');
var_dump($ce);
In this case $ce get cast to an object of stdClass when you try to set a property (certification_date).
Now your code:
function agent_certification_complete($certification_id, $client_no){
$ce = ClientPurchase::find('first', array('conditions' => "certification_id = '$certification_id' and is_certification = 1 and client_no='$client_no'"));
//$ce is probably false or null
//it gets cast to a stdClass object
$ce->certification_date = date('Y-m-d');
//stdClass does not have a transition method; ERROR
$ce->transition('passed'); **//Line 25**
$ce->save();
}
So in your code, if find() is returning null or false, or maybe some other choice values, $ce gets cast to a stdClass object on the next line. Then that stdClass object does not have a transition() method so you get an error.
To fix this, either adjust your find method or check its return value and handle accordingly.
As to it happening only in certain browser, I think thats a false conclusion. If find() is calling a query, it probably only happens at certain times depending on the result of that query.