The new year is here so it is time to get cracking on infrastructure for the year’s development projects. There are a number of things we have been putting off, but now that a number of our client hosts support PHP 5.3, it is the right time to move up the stack for our ORM from Doctrine 1.2 to Doctrine 2 (which feels more like Hibernate) than anything else.
Well step 1 was downloading it, I went straight to Github (https://github.com/doctrine) , got the Doctrine-ORM unpacked it dropped it into the library/Doctrine and was chugging away when I got errors. Seems like some classes were missing …
Tip #1: Download the ORM or DBAL packages from the main project website and you will get all required classes
Anyway classes in tow, I started cutting away at the Doctrine 1 classes to remove all that is not supported it is alot. Doctrine 1 was an Active Record implementation (http://en.wikipedia.org/wiki/Active_record) which meant that you had to extend a base class Doctrine_Record, while Doctrine 2 is a data mapper (http://martinfowler.com/eaaCatalog/dataMapper.html), you write POPOs (Plain Old PHP Objects) for which you provide the mapping metadata so the database access is handled by a service layer.
We chose to use PHP Annotations over YAML and XML so that we do not introduce any dependencies and maintain the mapping metadata within the model classes.
Next step was integration with Zend Framework, so I followed the instructions at the Mayflower Blog (http://blog.mayflower.de/archives/799-06.12.-Doctrine-2-Zend-Framework-Integration.html) with the following tweaks:
- Application.ini – instead of using doctrine.connectionParameters maintained the resources.db.params configuration which we use for storing sessions in the database using Zend_Session
- Bootstrap – load the resources.db settings and change configurations user to username and adapter to driver which Doctrine2 expects.
- Change production caching to ArrayCache since the shared hosts do not usually support APC, this will change on a project to project basis.
At least now the pages load now into the model configurations. We use two base classes BaseRecord was the one which extends Doctrine_Record in 1.2, and BaseEntity which provides commonly used properties id (autoincrement), datecreated, created by, lastupdate date and last updated by columns which are common to all tables.
First step was to add the mapping annotations, the column definitions are similar to Doctrine 1 with sensible defaults, which helps. However the associations were a mean piece of code, since the Doctrine 2 conventions are a total mismatch to normal database terminologies which I was used to. Opened a github issue too at https://github.com/doctrine/orm-documentation/issues/80 (my first Github and Open Source issue)
Anyway what is interesting in the association mapping is that the mapping columns are defined in the annotation and private variables are not defined for the mapping columns (at least I do not see that in the examples) may come back to bite me later when I start saving the entities, but that is for another time
So anyway classes setup, now the next problem I ran into. In Doctrine 1, the Doctrine_Record provided two methods:
- Merge – which merges data into the object
- SynchronizeWithArray – same as merge, but had an added function, if you have relations defined and do not pass information in them, then the relations are removed, which was excellent for cases where you need to remove relations in a hurry
Where does this leave me now, action items are:
- Setup automated binding of an array of data to the object, and how to deal with relations …
- Update the application code to enable an object to load its details from the database … seems crude I will look at what others do
- Add Validators since Doctrine2 provides none. Now I need to poke into how I can use Zend_Validators without too much overhead and new changes for my team …
Anha one last one, I wanted to have a PDF of the documentation, since I wanted to use it on my PC faster than opening pages, but none was available. I pinged Jonathan Wage (http://www.jwage.com/) and he pointed me to Read the Docs ( http://readthedocs.org/) which generates documentation for projects from Github etc, so you should check it out. Anyway I searched for Doctrine ORM documentation, downloaded a PDF and now I am in business.
All in a day’s work, and I hope to keep plodding and poking into it as promised.
My take on Day 1, the models feel light weight and more like POJOs, well I think PHP is becoming more and more enterprise ready as it supports core patterns of Enterprise Architecture a Martin Fowler religion that I subscribe to …
Till next time