li₃ Behaviors
This library provides base classes for implementing model behaviors.
Model behaviors provide a simple way to extend models. This pattern allow
common logic to be encapsulated inside behaviors for keeping models light
and composed only by its own business logic., (*1)
Installation
The preferred installation method is via composer. You can add
the library as a dependency via:, (*2)
composer require unionofrad/li3_behaviors
li₃ plugins must be registered within your application bootstrap phase
as they use a different (faster) autoloader., (*3)
Libraries::add('li3_behaviors')
The official manual has more information on
how to register the plugin
with the app or use alternative installation methods (i.e. via Git)., (*4)
Usage
Managing and Loading Behaviors
First to add the ability of using behaviors in a model, use
the behaviors trait in your model. After that define all behaviors you
plan to use in the $_actsAs property of the model class., (*5)
// ...
class Posts extends \lithium\data\Model {
use li3_behaviors\data\model\Behaviors;
protected $_actsAs = [
'Sluggable' => ['field' => 'slug', 'label' => 'title']
];
// ...
The Behaviors trait also makes some static methods available in the model,
which allows to manage behaviors as follows., (*6)
// Bind the sluggable behavior with configuration.
Posts::bindBehavior('Sluggable', ['field' => 'slug', 'label' => 'title']);
// Accessing configuration.
Posts::behavior('Sluggable')->config();
Posts::behavior('Sluggable')->config('field');
// Updating configuration.
Posts::behavior('Sluggable')->config('field', 'alt');
// Unbinding it again.
Posts::unbindBehavior('Sluggable');
Creating a Behavior
Now that we are able to load and manage behaviors we can create our own
behavior which must extend the Behavior base class. In the following example
we create a Sluggable behavior in extensions/data/behavior/Sluggable.php., (*7)
namespace app\extensions\data\behavior;
use lithium\util\Inflector;
class Sluggable extends \li3_behaviors\data\model\Behavior {
protected static $_defaults = [
'field' => 'slug',
'label' => 'title'
];
protected static function _filters($model, $behavior) {
Filters::apply($model, 'save', function($params, $next) use ($behavior) {
$params['data'][$behavior->config('field')] = static::_generate(
$params['data'][$behavior->config('label')]
);
return $next($params);
});
}
protected static function _generate($value) {
return strtolower(Inflector::slug($value));
}
}
Behavior Configuration
The configuration of each behavior can be accessed from within the
behavior via config(). By default configuration for the behavior will
be set automatically using the user provided configuration from the $_actsAs
property of the model and the defaults provided in the behavior as $_defaults., (*8)
The defaults are merged with the provided configuration using simple array
addition ($config += $defaults). If you want to change the way configuration
is merged read further., (*9)
Providing Custom Configuration Logic
Behaviors often come with different requirements towards configuration.
In some cases just a 1-dimensional array needs to be merged in other cases
nested multi-dimensional arrays must be merged
or even normalized in a custom way., (*10)
That's why merging the defaults with the provided configuration can be
controlled easily by yourself - the implementer. By default we do a simple
one-dimensional merge adding defaults and configuration to eachother. To
control configuration merging overwrite the _config() method of the base
class., (*11)
In the following example we will normalize certain configuration options
while merging with the behavior's defaults., (*12)
// ...
class Serializable extends \li3_behaviors\data\model\Behavior {
protected static $_defaults = [
'fields' => []
];
protected static function _config($model, $behavior, $config, $defaults) {
$config += $defaults;
$config['fields'] = Set::normalize($config['fields']);
foreach ($config['fields'] as $field => &$pass) {
if (!$pass) {
$pass = 'json';
}
}
return $config;
}
// ...
The _config() method gets the configuration and the defaults as defined in $_defaults as
the 3rd and 4th parameters. The method must finally return the configuration that should
be used for the behavior instance., (*13)
Exposing Static Methods to the Model
Any public static method present in the behavior is automically exposed on the model. This
allows for adding methods to the model easily. Each static method that is exposed gets
the name of the current model class as its first and the instance of the behavior as a second
parameter., (*14)
This is useful if you i.e. need to query the model for results or when you want to retrieve
configuration from the behavior., (*15)
The example below shows how we expose a token generation method to the model., (*16)
// ...
class TokenGenerator extends \li3_behaviors\data\model\Behavior {
protected static $_defaults = [
'short' => false
];
// Generates a random token either short (8 chars) or long (16 chars) and
// returns it. Default expiration is one year.
public static function token($model, $behavior) {
$token = substr(md5(Random::generate(32)), 0, $behavior->config('short') ? 8 : 16);
$expires = date('Y-m-d H:i:s', strtotime('+1 year'));
return compact('token', 'expires');
}
// ...
Exposing Instance Methods to the Model
Analog to exposing static methods, instance methods can also be exposed to the model easily. Any concrete
method implemented in the behavior will be exposed. Each behavior method will in addition to the $entity
parameter also receive the name of the model and an instance of the behavior as a second parameter i.e. to access configuration., (*17)
// ...
class Publishable extends \li3_behaviors\data\model\Behavior {
protected static $_defaults = [
'field' => 'is_published'
];
public function publish($model, $behavior, $entity) {
$field = $behavior->config('field');
$entity->{$field} = true;
}
// ...
Dynamically Adding Model Instance Methods
Sometimes you need to dynamically add methods to a model instance. I.e. when a field
name of a behavior is user configurable and needs to be added as a method on the entity., (*18)
This can be achived by overwriting the _methods() method and returning an array
of methods keyed by their alias on the model instance., (*19)
// ...
class Taggable extends \li3_behaviors\data\model\Behavior {
// ...
protected static function _methods($model, $behavior) {
return [
$behavior->config('field') => function() { /* ... */ }
]
}
// ...
The above exemplaric behavior would then enable the following
methods on each entity returned from the model., (*20)
Posts::bindBehavior('Taggable', ['field' => 'taxonomy']);
$item = Posts::create();
$item->taxonomy();
Attaching Filters to the Model
To modify existing model methods, filters should be used. If your behavior
needs to use filters a good place to attach them is the behavior's _filters()
method. Overwrite it to attach filters to the model during initialization phase., (*21)
// ...
class Timestamp extends \li3_behaviors\data\model\Behavior {
// ...
protected static function _filters($model, $behavior) {
Filters::apply($model, 'save', function($params, $next) use ($behavior) {
$params['data'] = static::_timestamp($behavior, $params['entity'], $params['data']);
return $next($params);
});
}
protected static function _timestamp($behavior, $entity, $data) {
// ...
}
// ...
Attaching Finders to the Model
To add finders to the model's find method, finders should be used. If your behavior
needs to use finders a good place to attach them is the behavior's _finders()
method. Overwrite it to add finders to the model during initialization phase., (*22)
// ...
class Taggable extends \li3_behaviors\data\model\Behavior {
// ...
protected static function _finders($model, $behavior) {
$model::finder('tag', function($params, $next) use ($behavior) {
// ...
return $next($params);
});
}
// ...
Copyright & License
Copyright 2010 Union of RAD. All rights reserved. This library
is distributed under the terms of the BSD 3-Clause License. The
full license text can be found in the LICENSE.txt file., (*23)
Credits for previous Implementations
- David Persson, https://github.com/davidpersson/li3_behaviors
- Nate Abele, https://github.com/nateabele/li3_behaviors
- Simon Jaillet, https://github.com/jails/li3_behaviors
Wallogit.com
