Request Lifecycle

Overview

When a request hits your Devux API, it flows through several layers in a specific order. Understanding this flow helps you know where to put your code.

The Flow

HTTP Request
     │
     ▼
┌─────────────┐
│ Controller  │  ← Receives request, orchestrates flow
└─────────────┘
     │
     ▼
┌─────────────┐
│  Validator  │  ← Validates input (Zod schema)
└─────────────┘
     │
     ▼
┌─────────────┐
│  Use-Case   │  ← Business logic (calls repos/services)
└─────────────┘
     │
     ▼
┌─────────────┐
│  Presenter  │  ← Formats output for response
└─────────────┘
     │
     ▼
HTTP Response

Step by Step

1. Controller

• Receives the HTTP request
• Extracts data from request (body, params, query)
• Calls the validator
• Calls the use-case
• Calls the presenter
• Sends the response

2. Validator

• Receives raw input data
• Validates against Zod schema
• Returns typed, validated data
• Throws validation error if invalid

3. Use-Case

• Receives validated input
• Executes business logic
• Calls repos for data access
• Calls services for additional operations
• Returns result (or throws business error)

4. Presenter

• Receives use-case output
• Transforms to response format
• Handles success/error formatting
• Returns final response body

Error Handling

Errors at any layer bubble up and are caught by the controller, which formats them appropriately:

• Validation errors → 400 Bad Request
• Business errors → 4xx (depends on error type)
• Unexpected errors → 500 Internal Server Error

Transaction Boundaries

The use-case is wrapped in a database transaction. If the use-case throws, all database operations are rolled back automatically.