Many-Many relations

Since POG 1.0 was launched about a year ago now, there has been numerous requests for object relations. POG 2.0 addressed the issues of parent-child (1-many, many-1) relations. Still, more work needed to be done for POG to really be useful in situations where many-many relations were needed. POG 2.5, released about a week ago, finally provides a simple, yet, powerful solution: Sibling Relations.

In the POG world, a sibling is an object that relates to one or many other sibling objects. Real world examples include the relations between Magazine and Subscribers: A subscriber can subscribe to one or more different magazines.

The object methods generated by POG to abstract many-many relations are similar to the ones generated for parent – child relations. We kept the API consistent so that the objects remain intuitive, and yet, are more powerful. The programmer can almost forget the underlying relations.

For instance, let’s say we have a Magazine and Subscriber object which are siblings. To associate a Magazine to a Subscriber, we only need to do something like this:

$subscriber->AddMagazine($magazine);

The thing to note here is that if Subscriber and Magazine were parent and child, instead of siblings, the code would still be

$subscriber->AddMagazine($magazine);

On the database level, however, the way the data is stored by POG is quite different. In the case of a parent-child relation, the child simply refers to the parentId using a column in the child table. In the case of siblings, POG generates a mapping (join) table which stores the sibling1_id and sibling2_id of related sibling. The data is inserted, retrieved and deleted from this mapping table transparently and does not have to be accessed directly by the developer.

More info on sibling relations can be found in the POG relations PDF document

We hope that the introduction of sibling relations will help accelerate your development even more.