Event dispatching in Laravel - Step-by-Step Execution

Concept Flow - Event dispatching

Trigger Event in Code

↓

Create Event Object

↓

Dispatch Event

↓

Listeners React

↓

Perform Actions

↓

Finish Event Cycle

This flow shows how Laravel creates and dispatches an event, then listeners respond to it.

Execution Sample

Laravel

event(new UserRegistered($user));

class UserRegistered {
  public $user;
  public function __construct($user) {
    $this->user = $user;
  }
}

This code creates a UserRegistered event with a user and dispatches it to listeners.

Execution Table

Step	Action	Event Object State	Listeners Called	Result
1	Create UserRegistered event with user data	UserRegistered { user: UserObject }	None yet	Event object ready
2	Dispatch event using event() helper	UserRegistered { user: UserObject }	Listener1, Listener2	Listeners start processing
3	Listener1 handles event	UserRegistered { user: UserObject }	Listener2 pending	Listener1 sends welcome email
4	Listener2 handles event	UserRegistered { user: UserObject }	None	Listener2 logs registration
5	Event dispatch cycle ends	UserRegistered { user: UserObject }	None	All listeners done

💡 All listeners have processed the dispatched event, ending the cycle.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 5
eventObject	null	UserRegistered { user: UserObject }	UserRegistered { user: UserObject }	UserRegistered { user: UserObject }
listenersCalled	[]	[]	[Listener1, Listener2]	[Listener1, Listener2]

Key Moments - 2 Insights

Why do listeners get called after dispatching the event?

Because dispatching triggers Laravel's event system to find and run all listeners registered for that event, as shown in steps 2 to 4 in the execution table.

What is inside the event object when dispatched?

The event object holds the data passed during creation, like the user in UserRegistered, visible in the eventObject variable in the tracker and step 1.

Visual Quiz - 3 Questions

Look at the execution table, what happens at step 3?

A Event object is created

B Listener1 sends a welcome email

C Listeners finish processing

D Event dispatch cycle ends

💡 Hint

Check the 'Result' column at step 3 in the execution table.

At which step are all listeners done processing the event?

A Step 5

B Step 4

C Step 2

D Step 1

💡 Hint

Look at the 'Listeners Called' and 'Result' columns in the execution table.

If the event object had no user data, what would change in the variable tracker?

A eventObject would be null after step 1

B listenersCalled would be empty after step 5

C eventObject would have no user property after step 1

D listenersCalled would include extra listeners

💡 Hint

Check the 'eventObject' row in variable_tracker after step 1.

Concept Snapshot

Laravel Event Dispatching:
- Create an event class with data.
- Dispatch event using event(new EventClass(data)).
- Laravel calls all registered listeners.
- Listeners perform actions like sending emails.
- Event cycle ends after all listeners run.

Full Transcript

In Laravel, event dispatching starts by creating an event object with data, like a user. Then, the event is dispatched using the event() helper. Laravel finds all listeners registered for that event and calls them one by one. Each listener performs its task, such as sending emails or logging. After all listeners finish, the event dispatch cycle ends. Variables like the event object and listeners called change during this process, as shown in the execution table and variable tracker.