Recently i moved to Symfony 2 and i have a litte question.
Let’s say i have the following Model:
“catalog” which contains “catalogs”. The model gets its data from files but also needs a database connection to verify things.
In the Zend framework or other past projects i loaded the dependencies by a static object which forms a kind of “registry”.
As i understand, Symfony 2 uses their service pattern (dependencie injection) instead. But how does this apply to my case.
Must i create a service for every model class i use to auto inject all dependencies? Or is it perfectly valid when i create a instance from my object myself and set for example the database connection in my constructor?
To create a service for every class which needs dependencies, seems a little bit overkill to me.
You can certainly create classes and inject dependencies the old-fashion way but take the time to learn the details of creating services. I think you will find:
Adding a new service is trivial. Copy/paste a few lines of configuration, adjust the class, id and maybe some parameters and you are done. Takes much less time than creating the actual class.
Very soon you will progress from just injecting a database connection to injecting other services as well as perhaps some parameters. Do you really want to have to remember to do all that stuff each time you need to new an object?
Using service id’s can divorce your controllers from the exact location/name of a class. The first time you need to do some refactoring and maybe move some services into their own bundle or perhaps swap out a service with another you will be glad that you won’t need to hunt down all your code and make changes.
S2 is not really focused on “Models”. Instead, think in terms of a service named CatalogManager which wraps access to assorted catalog functionality.