The third block shows the configuration options required to connect to a database.
In this case, we’ll use a file-based SQLite database.
Metadata for an Entity can be configured using Doc Block annotations directly in the Entity class itself, or in an external XML file.
This Getting Started guide will demonstrate metadata mappings using two methods, but you only need to choose one.
Hydration is the most costly in terms of time and ORM memory.
That’s why when receiving large amount of data from the database only to display it, for example when retrieving a list, hydrating everything into entities objects will be very costly.
You have to configure and create it to use your entities with Doctrine 2.
I will show the configuration steps and then discuss them step by step: .
That’s why we have 5 more requests for the authors of the posts.
In order to optimize the Doctrine 2 ORM query we need to use JOIN and add the required entities to the sample.
Here is the optimized repository method code for obtaining a list of posts.
Doctrine 2 is an object-relational mapper (ORM) for PHP 5.4 that provides transparent persistence for PHP objects.
It uses the Data Mapper pattern at the heart, aiming for a complete separation of your domain/business logic from the persistence in a relational database management system.