Implement Controller Endpoint

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In this lesson, we'll implement a controller endpoint that lets event organizers retrieve the details of a specific event.

Implement the Controller Endpoint

The get event endpoint needs to handle both successful and unsuccessful requests. Let's implement this in our EventController:

@GetMapping(path = "/{eventId}")
public ResponseEntity<GetEventDetailsResponseDto> getEvent(
        @AuthenticationPrincipal Jwt jwt,
        @PathVariable UUID eventId
) {
    // Get the user's ID from the JWT token
    UUID userId = parseUserId(jwt);

    // Call the service layer and transform the response
    return eventService.getEventForOrganizer(userId, eventId)
            .map(eventMapper::toGetEventDetailsResponseDto)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
}

Let's break down what's happening:

We use @GetMapping with a path parameter {eventId} to capture the event identifier
The @PathVariable annotation maps the URL path parameter to our method parameter
We extract the user ID from the JWT token using our helper method
We use the service layer to find the event, which returns an Optional
We chain map operations to convert the event to a DTO and wrap it in a response
If no event is found, we return a 404 Not Found response

Error Handling

Our endpoint handles two main cases:

When the event exists and belongs to the organizer, it returns HTTP 200 with the event details
When the event doesn't exist or doesn't belong to the organizer, it returns HTTP 404

This approach follows REST best practices by using standard HTTP status codes to communicate the outcome of the request.

Summary

Implemented a GET endpoint to retrieve event details by ID
Used Optional to handle cases where events aren't found