延迟加载实体的Doctrine Repository机制如何工作？

Question

So, I want to understand how the Doctrine Repository mechanism works.

For my entities I use annotations, so the resulting object is built somewhere during the execution of the script.

I'd like to unserstand which are the possibile ways of implementing the lazy loading of entities from another entity.

In concrete, using Doctrine, I have the ability to fetch information of related object (from the Symfony book). This fetching is done in a lazy way: only if I call the method to get the information about the Entity it is loaded from the database querying it.

Now, I'd like to better understand this mechanism: how an entity can implement repository methods? How can I reproduce this mechanism to implement it in other context similar to the one of a database data retrieval?

As the resulting object is really big, is there someone who can put me on the right way? Which classes should have I read to understand the mechanism? Are there any articles/posts that better explain how this mechanism is implemented? Are there better (or simply simpler) ways of implementing it?

Answer 1

I think the best description of the lazy loading can be found in Doctrine developer articles. http://www.giorgiosironi.com/2009/07/lazy-loading-of-objects-from-database.html http://www.giorgiosironi.com/2009/08/doctrine-2-now-has-lazy-loading.html

The main idea is to insert into Product's category list a set of objectes that are subclasses of Category. These and called "proxy objects" and created "on the fly" when Product is retrieved from database. These proxy objects have the same interface as Category object, but add functionality of loading actual Category items from database when needed.