Logger

The built-in Logger service provides structured, colored logging with context labels.

Basic Usage

import { Logger } from 'next-js-backend';

// Create with context name
const logger = new Logger('UserService');

logger.log('User created: u_123');
logger.warn('Session about to expire');
logger.error('Database connection failed', error.stack);
logger.debug('Resolving dependency: UserService');
logger.verbose('Incoming request headers', headers);

In Services

import { Injectable } from 'next-js-backend';
import { Logger } from 'next-js-backend';

@Injectable()
export class UserService {
  private readonly logger = new Logger(UserService.name);

  async findById(id: string) {
    this.logger.log(`Looking up user: ${id}`);
    const user = await this.repo.findById(id);
    if (!user) {
      this.logger.warn(`User not found: ${id}`);
      return null;
    }
    return user;
  }
}

Log Levels

Method	Level	Color
.log()	INFO	Green
.warn()	WARN	Yellow
.error()	ERROR	Red
.debug()	DEBUG	Blue
.verbose()	VERBOSE	Cyan

Log Format

[2024-03-16 10:30:15] [UserService] ℹ User created: u_123
[2024-03-16 10:30:16] [AuthGuard] ⚠ Invalid token received
[2024-03-16 10:30:17] [DatabaseService] ✖ Connection refused

Using in the Factory

The ElysiaFactory uses Logger internally for startup messages:

[ElysiaFactory] ℹ Registered route: GET /api/users
[ElysiaFactory] ℹ Application started on port 3000