datamapper

I asked a similar question a while back: Using the Data Mapper Pattern, Should the Entities (Domain Objects) know about the Mapper? However, it was generic and I'm really interested in how to accomplish a few things with Doctrine2 specifically . Here's a simple example model: Each Thing can have a Vote from a User , a User may cast more than one Vote but only the last Vote counts. Because other data ( Msssage , etc) is related to the Vote , when the second Vote is placed the original Vote can't just be updated, it needs to be replaced. Currently Thing has this function: public function addVote

Well I've been trying to find out the difference between data mapper and repository, but up to now I still have not. It seems to me that the expert programmer said "Repository is another layer of abstraction over the mapping layer where query construction code is concentrated". It seems understandable but is still somewhat very abstract. I read this article on stackoverflow before, and it just made me even more confused: How is the Data Mapper pattern different from the Repository Pattern? I guess what I need are simple explanations and concrete/practical examples on how the two patterns

I'm working with Doctrine2 for the first time, but I think this question is generic enough to not be dependent on a specific ORM. Should the entities in a Data Mapper pattern be aware - and use - the Mapper ? I have a few specific examples, but they all seem to boil down to the same general question. If I'm dealing with data from an external source - for example a User has many Messages - and the external source simply provides the latest few entities (like an RSS feed), how can $user->addMessage($message) check for duplicates unless it either is aware of the Mapper, or it 'searches' through

I'm using datamapper with ruby to store data to certain tables. Several of the tables have very large amounts of information and I want to clear them out when the user 'rebuilds database' (it basically deletes everything and re-calculates data). I originally tried Forum.all.destroy and did it for all the different tables, but I noticed some of them just werent deleted from within phpmyadmin. i can only imagine its because of foreign keys. Although I really dont know because my other table which foreing keys was successfully deleted. Not to mention, id rather just 'zero' it out anyway so the

I have entities which I would like to eagerly load , and on other ocassions lazy (or even extra lazy) load. My mappings have no fetch mode declared in my YAML- so they use the default (lazy loading). Currently the only way to eagerly load is to by constructing the DQL manually - and I need to update this every time I add a new entity. Ideally I would just load the root entity and the force eager loading all the associated objects. Is there any way I can do this? If not why (is there a reason beyond it being an unimplemented feature)? If you want to use built-in repository methods (find(),