The problem I discovered was that obviously Doctrine didn’t know what the conditional relationships were, since it was dependant on the type column. I researched some different approaches:

1. Doctrine’s RawSql

   This approach worked for generating the correct SQL query without a problem, but the issue then arose of how Doctrine could hydrate the result set. Answer was – it couldn’t :-) Well, I lie – I could use Doctrine::HYDRATE_SCALAR but I had issues with other related models, where I was joining to a table twice but under different aliases, which failed, since the scalar hydration would override earlier joins on the same table.

2. Column aggregation

   Column aggregation looked great initially – I could have a “TypeAEntry” and a “TypeBEntry”, and Doctrine would have handled the typing of the Entry automatically. I couldn’t however see a way to query “in reverse” – get all Entries and their associated models.

3. Write a raw SQL query, and use Doctrine’s PDO instance to retrieve the data.

Option 3) was the one I settled for in the end. It meant of course that I had to specify column names, and perform all the joins myself, but it did mean I could specify precisely what data I wanted back. This came back in the form of a normal array.  I’d tried to stay away from this option intially, but after spending too long researching the other 2 and hitting brick walls, I bit the bullet and dropped down to the raw stuff.  And hey presto!

Note – this approach will only work if you want the data to be read-only. If you want to then use Doctrine’s model goodness, you’ll need to work out how to transform that *back* into a model.

One such tool is the Propel ORM which gives us objects to represent the tables we have in databases, it reduces the amount of SQL you have to write in an application to almost nil.

Sometimes however searching for information in a table can be a lot harder in Propel that it would be in SQL, you have to use “Criteria” objects and they are not as intuitive as they should be.

However François Zaninotto, one of the creators of the Symfony framework, has written a finder plugin for Propel Objects called sfPropelFinderPlugin which aims to make this process a lot easier and more intuitive.

// With Peer and Criteria
$c = new Criteria()
$c->add(ArticlePeer::TITLE, '%world', Criteria::LIKE);
$c->add(ArticlePeer::IS_PUBLISHED, true);
$c->addAscendingOrderByColumn(ArticlePeer::CREATED_AT);
$articles = ArticlePeer::doSelect($c);
// with sfPropelFinder
$articles = sfPropelFinder::from('Article')->whereTitle('like', '%world')->whereIsPublished(true)->orderByCreatedAt()->find();

If you use Propel outside of Symfony you can also use this plugin as it is standalone.

I like the quote from the wiki page.
“Think of sfPropelFinder as jQuery for Propel”