CakePHP Finite State Machine Behavior
A basic finite state machine behavior for CakePHP 2.x. A version for CakePHP 1 can be found in the branch cakephp1.
Describe a model's states and the events that cause transitions between them, then trigger these events to change your model to a new state.
Installation
If you're using composer then just add the following to your require block.
"burriko/cake-state-machine": "2.0.*@dev"
If you're not, then clone/copy the contents of this directory to app/Plugins/CakeStateMachine.
Configure
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Add the following line to your app/Config/bootstrap.php.
CakePlugin::load('CakeStateMachine');
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In your model add:
public $actsAs = array('CakeStateMachine.StateMachine');
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Create a new database table to store the states using the following schema, adjusting the table name and foreign key to match your model. For example, if you are adding states to a model name Placement you would use the following.
CREATE TABLE `placement_states` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `placement_id` int(11) unsigned NOT NULL, `state` varchar(50) NOT NULL DEFAULT '', `created` datetime NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
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Add a new varchar field to your model's table called 'state'.
ALTER TABLE `placements` ADD `state` VARCHAR(50);
Usage
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In your model describe the states and transitions you need like so.
public $states = array('state' => array('event' => 'new_state'));
Here's an example.
public $states = array( 'advertised' => array( 'select_appropriate_applicants' => 'shortlisted', 'no_appropriate_applicants' => 'unplaced' ), 'shortlisted' => array( 'select_for_interview' => 'interviews', 'no_appropriate_applicants' => 'unplaced' ), 'interviews' => array( 'select_successful_candidate' => 'placed', 'no_appropriate_applicants' => 'unplaced' ), 'placed' => array( 'placement_complete' => 'complete', 'problem_with_placement' => 'unplaced' ), 'unplaced' => array( 'readvertise' => 'advertised' ), 'complete' );
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When a new record is created by that model it will be assigned the first state in the list as it's initial state.
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To transition to a new state call pass the name of an event to the transition() method.
$this->Model->transition('event');
In this example if the Placement model was in the 'interviews' state it would transition to the 'placed' state.
$this->Placement->transition('select_successful_candidate');
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Every state change is recorded in the database. Every model that uses the StateMachine behavior will have an appropriate state model named ModelnameState. The model is related to this with a hasMany relationship. You can therefore use this model to look up state changes however you want.
$this->Placement->PlacementState->findByPlacementId($placement_id);
You can also find the current state of a model from the getCurrentState() method.
// set model id if not already set $this->Placement->id = $placement_id; $this->Placement->getCurrentState(); // returns 'placed'
Notes
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The current state of a record is also stored in the 'state' column of the model. This is to make it easier when querying the model by state.
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A callback method is supported for state changes. This should be titled _onState(). For example, to run a method when the model changes to a state named 'placed' add the following method to your model.
public function _onStatePlaced() {}
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You can check whether a state is currently set by calling is<NameOfState>(). For example to check whether a Placement record is currently set to shortlisted call the following.
$this->Placement->isShortlisted();