This diagram visualizes the Ticket Booking Flow, demonstrating how the Controller, Service, and Database layers interact to handle bookings and concurrency.
Mermaid Source
sequenceDiagram
participant User
participant Frontend
participant "Booking Controller" as Controller
participant "Booking Service" as Service
participant "Data Access Layer" as DB
User->>Frontend: Select Event & Ticket Type
Frontend->>Controller: POST /api/bookings (eventId, ticketType)
activate Controller
Controller->>Service: createBooking(req.user.id, eventId, ticketType || "general")
activate Service
Service->>DB: findEventById(eventId)
activate DB
DB-->>Service: Event Details (capacity, bookedCount)
deactivate DB
alt Ticket Available
Service->>DB: incrementBookedCount(eventId)
activate DB
DB-->>Service: Success
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Service->>DB: saveBooking(userId, eventId, ticketType, amount)
activate DB
DB-->>Service: Booking Object
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Service-->>Controller: Booking Success
Controller-->>Frontend: 201 Created (Booking Details)
Frontend-->>User: Show Booking Confirmation & QR Code
else Ticket Sold Out
Service-->>Controller: Error: Tickets Sold Out
Controller-->>Frontend: 400 Bad Request
Frontend-->>User: Show Sold Out Message
end
deactivate Service
deactivate Controller