Extending.md

Extending

Generally extending is accomplished with PHP's native Traits. You can also add functionality to be called on event trigger e.g. "save", "delete" etc. And you can add your own methods to the Find classes, by extending it.

Extending with traits

A quick naive implementation of slugs.

use Harp\Harp\Repo\Event;

trait ExtensionTrait
{
    public static function initialize($config)
    {
        // Here you can work with the config object as if you're in the model's initialize method itself
        $config->addEventAfter(Event::CONSTRUCT, function ($model) {
            $model->updateSlug();
        });
    }

    // Add a property to the model
    // By default all public properties are saved in the database
    public $slug;

    // adding a new function to search with from the model
    public static function findBySlug($slug)
    {
        // static keyword will refer to the class this trait will be extending
        return static::where('name', $slug)->loadFirst();
    }

    // add a method to the model itself
    public function updateSlug()
    {
        $this->slug = $this->id.$this->name;
    }
}

// In the model
class User extends AbstractModel
{
    use ExtensionTrait;

    public static function initialize($config)
    {
        ExtensionTrait::initialize($config);

        // ...
    }
}

Using events

You can subscribe to several events that get triggered in the life-cycle of models. All of these events are in the Harp\Harp\Repo\Event class:

Event	Action
Event::CONSTRUCT	Called after the constructor of the model has been executed
Event::INSERT	Called when the model is being inserted in the database
Event::UPDATE	Called when an already saved model is being updated
Event::DELETE	Called when a model is being deleted from the database. Works for normal and soft delete
Event::SAVE	Called either on INSERT or UPDATE
Event::VALIDATE	Called when a model is being validated. E.g. the "validate" method is being called. This is useful to add some custom validation before / after

All of these events have a "before" and "after" phase. Except "CONSTRUCT", which only has "after".

Here's an example:

use Harp\Harp\AbstractModel;
use Harp\Harp\Repo\Event;

class User extends AbstractModel
{
    public static function initialize($config)
    {
        $this
            ->addEventAfter(Event::SAVE, function ($model) {
                $model->preseveSave();
            })
            ->addEventBefore(Event::DELETE, function ($model) {
                $model->cleanUpDelete();
            });
    }
}

Extending Find

The Find class has a variety of methods for adding sql constraints. Methods like where, join, group, order etc. Sometimes you'll want to add your own methods there, specific to the repo. To do this you need to create your own class, extending Find, and modify the "findAll" method on the model to return your own class.

// In the repo
use Harp\Harp\AbstractModel;

class User extends AbstractModel
{
    // ...

    public static function findAll()
    {
        return new MyFind(static::getRepo());
    }
}

// Find class
use Harp\Harp\Find;

class MyFind extends Find
{
    public function whereSlug($slug)
    {
        return $this->where('slug', $slug);
    }
}