Returning the correct class from a DBRef

[tonymillion]

I have a notification system where numerous objects could create a notification as such:

protected static $_requirements = array(
    'object'        => array('AsReference'),
);

further in the code $this->object is set to the object creating the notification (could be one of 4 types (so far)).

in the database it looks like:

'object' => 
  array (
    '$ref' => 'users',
    '$id' => new MongoId("4f721182304fbef21c000001"),
  ),

however when I come to dereference the object using $notification->object its always returned as a Shanty_Mongo_Document and not as a user object. Is there a way to get Shanty to return the right type based on the _type in the user object?

[coen-hyde]

Ah interesting. Yes maybe we can create a custom db ref with a _type.

[gwagner]

I have committed this in a new patch (2c44e606b0aea834a3e3f7aa917580204ddb511d) but here is the code in the mean time to fix your problem:

In getProperty() in Shanty_Mongo_Document, add this code:

<?php
/* try and grab the class name from the data first */
if(!$className && !empty($data) && isset($data['_type']) && count($data['_type']) >= 1 && class_exists($data['_type'][0]))
    $className = $data['_type'][0];

to this block:

<?php
// Find out the class name of the document or document set we are loaded
if ($className = $this->hasRequirement($property, 'DocumentSet')) {
    $docType = 'Shanty_Mongo_DocumentSet';
}
else {
    $className = $this->hasRequirement($property, 'Document');

    /* try and grab the class name from the data first */
    if(!$className && !empty($data) && isset($data['_type']) && count($data['_type']) >= 1 && class_exists($data['_type'][0]))
        $className = $data['_type'][0];

    // Load a document anyway so long as $data is not empty
    if (!$className && !empty($data)) {
        $className = 'Shanty_Mongo_Document';
    }

    if ($className) $docType = 'Shanty_Mongo_Document';
}

Normally what you could do is set a requirement with

<?php
protected static $_requirements = array(
    'object'        => array('Document:ObjectType', 'AsReference'),
);

But in your case with your mutating document type, my patch above will detect the document type out of the result rather than from a config file

[gwagner]

Also, digging through the code, it seems that $docType is old and currently unused. Do you remember what the original purpose of $docType was for?

[coen-hyde]

Thanks gwagner, I forgot how Shanty Mongo worked. What you are supposed to do is:

<?php
protected static $_requirements = array(
  'object'        => array('Document:User', 'AsReference'),
);

There is a problem with this though. You wouldn't be able to store references to documents of different types.

[gwagner]

That is where my patch comes in, we can get the object type off of the data being returned before we instantiate a generic object

[tonymillion]

I use things like:

<?php
protected static $_requirements = array( 'object' => array('Document:User', 'AsReference'));

Quite heavily in my code to enforce type, but in this case needed the type to mutate, thus the assumption on using just AsReference, I'm about to test the fix @gwagner pasted here, and will let you know.

[gwagner]

Tony (if that is your real name) how did the code snippet work?

[tonymillion]

It is indeed my real name! And, yes, it worked perfectly, never got a chance to reply again last night. Thanks for the quick fix!

[gwagner]

Wonderful. I have the code pushed to my branch (with corrected test) waiting to be integrated into the mainline.