services-structure.md

Services Structure

Base Structure

import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';

@Injectable()
export class ModuleService {
  constructor(
    private readonly repository: ModuleRepository,
    private readonly blockchainService: BlockchainService,
  ) {}

  async findAll(): Promise<Module[]> {
    return this.repository.findAll();
  }
}

Responsibilities

• Business logic: All logic should be here
• Orchestration: Coordinates calls to repositories, blockchain, other services
• Business validations: Rules that are not input validation
• Transformations: Converts data between layers

Dependency Injection

• Use constructor to inject dependencies
• Type all dependencies
• Avoid circular dependencies

Conventions

• Name: {Module}Service
• File: {module}.service.ts
• @Injectable() decorator always present
• Async methods when there's I/O
• Return explicit types (no any)

Error Handling

• Throw specific NestJS exceptions
• Don't catch errors unless transforming them
• Let filters handle response formatting