On using Laravel with the repository pattern and Eloquent

Separation of concerns is a design principle, and states that each part of a software addresses a separate concern. Different patterns and abstractions can be used for that like MVC, DAOs and repositories.

Repositories help in the abstraction of the data layer. It provides an interface for retrieving data, independent of the implementation, acting like a collection of objects.

In Nestor-QA I had implemented repositories using some Java code I had in my mind, without paying too much attention to the abstraction layers. Two weeks ago, while working on some complicated issue in Nestor I noticed that the repositories in Nestor had been implemented using the Eloquent classes.

Eloquent is a library used in Laravel for data abstraction. It provides access to databases like MySQL and SQLite, kind like DAOs (and sometimes like repositories too). However, for Nestor being a test management tool, we are trying to be platform and framework independent. Here’s the old repository code in action:

class DbProjectRepository implements ProjectRepository {

    public function all()
    {
        return Project::where('project_statuses_id', '<>', 2)->get();
    }

    // ...

}

As you can see, we were returning the result of the get() method from Eloquent. Another big mistake was using these objects in the views. In the end we were not only using data layer elements in the wrong place, but we also had many queries to render an UI.

abstract class DbBaseRepository extends BaseRepository {

    protected $model;

    public function __construct($model)
    {
        $this->model = $model;
    }

    public function all()
    {
        return $this->model->all()->toArray();
    }

    // ...
}

After searching for a while, I found a nice example of a class design for repositories, where the return type is always an array. In the views you will have the array and keys, and in case someday you decide moving to another framework, you can leave the views unchanged (hopefully :-). Neat, no?

Happy hacking