DMZ 1.7.1 (DataMapper OverZealous Edition)

[eluser]TheJim[/eluser]
@rideearthtom

Right, that was probably unclear. I was just referring to the mistakes in my earlier post, not to any negative tone I was inferring from your response or anything like that. Just so we're clear.

@Overzealous and whoever else

So, to anyone interested in many-to-many reciprocal self relationships (say, documents related to each other where saving/deleting the relationship in one direction should also maintain the relationship in the reverse direction), the following may be useful. And when Phil gets some time, it might be small enough and handy enough to warrant permanent inclusion in DMZ. It's one of those things that seems to come up fairly often, and I think it makes sense for DMZ to manage it.

Anyway, the implementation that seemed convenient to me was to set up an additional option ('reciprocal') in the $has_many definition.

Code:

class Document extends DataMapper
{
    public $has_many = array('comment',
                'related_document'=>array(
                        'class'=>'document',
                        'other_field'=>'document',
                        'reciprocal'=>TRUE
                    ),
                 'document'=>array(
                        'other_field'=>'related_document'
                    )
        );
}

The changes necessary are pretty simple. In DMZ 1.7.1:

Code:

Starting at Line 649

if( ! isset($rel_props['join_other_as']))
{
    // add the key as the model to use in queries if not set
    $rel_props['join_other_as'] = $related_field;
}
if(isset($rel_props['reciprocal']))
{
    // only allow a reciprocal relationship to be defined if this is a has_many self relationship
    $rel_props['reciprocal'] = ($rel_props['reciprocal'] && $arr == 'has_many' && $this_class == $rel_props['class']);
}
else
{
    $rel_props['reciprocal'] = FALSE;
}
$new[$related_field] = $rel_props;

Code:

Starting at Line 4847

else if (isset($object->has_many[$other_field]))
{
    // We can add the relation since this specific relation doesn't exist, and a "has many" to "has many" relationship exists between the objects
    $this->db->insert($relationship_table, $data);

    // Self relationships can be defined as reciprocal -- save the reverse relationship at the same time
    if ($related_properties['reciprocal'])
    {
        $data = array($this_model . '_id' => $object->id, $other_model . '_id' => $this->id);
        $this->db->insert($relationship_table, $data);
    }

    return TRUE;
}

Code:

Starting at Line 4980

else
{
    $data = array($this_model . '_id' => $this->id, $other_model . '_id' => $object->id);

    // Delete relation
    $this->db->delete($relationship_table, $data);

    // Delete reverse direction if a reciprocal self relationship
    if ($related_properties['reciprocal'])
    {
        $data = array($this_model . '_id' => $object->id, $other_model . '_id' => $this->id);
        $this->db->delete($relationship_table, $data);
    }
}

Unless I'm mistaken, that's all it takes, but of course I'm open to ideas if I've missed an important detail or there's some other avenue for improvement.