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Laravel State workflow

Implement Symfony Workflow component in Laravel

A workflow consist of state and actions to get from one place to another. The actions are called transitions which describes how to get from one state to another.

Installation

For Laravel versions lower than 5.5, this step is important after running above script.

• Open your config/app.php file and add custom service provider:

Publish config/workflow.php file

Run migrations

Configuration

1. Open config/workflow.php and configure it

2. Add HasWorkflowTrait to your model class to support workflow

Usage

Manage State/Workflow

Fired Event

Each step has three events that are fired in order:

• An event for every workflow
• An event for the workflow concerned
• An event for the workflow concerned with the specific transition or state name

During state/workflow transition, the following events are fired in the following order:

1. Validate whether the transition is allowed at all. Their event listeners are invoked every time a call to workflow()->can(), workflow()->apply() or workflow()->getEnabledTransitions() is executed. Guard Event

2. The subject is about to leave a state. Leave Event

3. The subject is going through this transition. Transition Event

4. The subject is about to enter a new state. This event is triggered just before the subject states are updated. Enter Event

5. The subject has entered in the states and is updated. Entered Event

6. The subject has completed this transition. Completed Event

Subscriber

Create subscriber class to listen to those events and the class should extends WorkflowSubscriberHandler.

To register method to listen to specific even within subscriber use the following format for method name:

• on[Event] - onGuard()
• on[Event][Transition/State name] - onGuardActivate()

NB:

• Method name must start with on key word otherwise it will be ignored.
• Subscriber class must be register inside workflow.php config file with the appropriate workflow configuration.
• Subscriber class must extends WorkflowSubscriberHandler.
• Guard, Transition and Completed Event uses of transition name.
• Leave, Enter and Entered Event uses state name.

Event Methods

Each workflow event has an instance of Event. This means that each event has access to the following information:

• getOriginalEvent(): Returns the Parent Event that dispatched the event which has the following children methods:
  • getSubject(): Returns the object that dispatches the event.
  • getTransition(): Returns the Transition that dispatches the event.
  • getWorkflowName(): Returns a string with the name of the workflow that triggered the event.
  • isBlocked(): Returns true/false if transition is blocked.
  • setBlocked(): Sets the blocked value.

Artisan Command

Symfony workflow uses GraphvizDumper to create the workflow image by using the dot command. The dot command is part of Graphviz.

You will be required to download dot command to make use of this command. https://graphviz.gitlab.io/download/

Usage