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Module Structure

A module is the basic building block of the Zochil API. Each module represents a specific business domain and contains two essential files: routes.ts and service.ts.

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Module Pattern

domain_module/
├── routes.ts    # Route definitions and Express router
└── service.ts   # Business logic and data access

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Routes (routes.ts)

The routes.ts file creates and exports an Express Router. It handles HTTP route definitions, request validation, and middleware integration.

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Example Route File

import { Router } from "express";
import { body as checkBody } from "express-validator";
import SomeService from "./service";
import { DBConnection } from "core/types";

export default (db: DBConnection) => {
  const routes: any = Router();
  const service = new SomeService(db);

  routes.get(
    "/list",
    service.handleOk(async (req) => await service.getAll(req.query))
  );

  routes.post(
    "/create",
    [checkBody("name").notEmpty()],
    service.handleOk(async (req) => await service.createRecord(req.body))
  );

  return routes;
};

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Route Responsibilities

  • Express Router: Create and configure HTTP routes
  • Validation: Input validation with express-validator
  • Authentication: Apply authentication middleware
  • Response Handling: Use service.handleOk() for consistent responses
  • Dependency Injection: Receive DBConnection from parent router

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Services (service.ts)

The service.ts file contains the business logic and data access layer. All service classes extend the base APIService class.

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Example Service File

import APIService from "core/base/service";
import { DBConnection, ID } from "core/types";

export default class SomeService extends APIService {
  constructor(db: DBConnection) {
    super(db, "table_name");
  }

  async getAll(filters = {}) {
    return await this.findForList(filters);
  }

  async createRecord(data: any) {
    return await this.create(data);
  }
}

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Service Responsibilities

  • Business Logic: Core domain logic and data processing
  • Database Access: Query database using Knex.js patterns
  • Multi-tenancy: Automatic filtering by shop_id/merchant_id
  • Error Handling: Use CustomError for structured exceptions
  • Event Publishing: Publish domain events via this.publishEvent()

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Base Classes

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APIService Base Class

Located at ./api/@core/base/service.ts, provides common functionality: 
import APIService from "core/base/service";

export default class ModuleService extends APIService {
  constructor(db: DBConnection) {
    super(db, "module_table_name");
  }

  // Inherited methods available:
  // - findForList(filters, pagination)
  // - findOneOrThrow(id)
  // - create(data)
  // - update(id, data)
  // - publishEvent(eventName, data)
}

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Merchant Service Composition

For merchant-related functionality, use the MerchantService as a composed property: 
import APIService from "core/base/service";
import MerchantService from "core/merchants/service";
import { DBConnection } from "core/types";

export default class ModuleWithMerchant extends APIService {
  private _merchantService: MerchantService;

  constructor(db: DBConnection) {
    super(db, "module_table_name");
    this._merchantService = new MerchantService(db, "shops");
  }

  async getMerchantData(merchantId: string) {
    return await this._merchantService.findOneOrThrow(merchantId);
  }
}

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Database Connection

All modules receive a DBConnection interface containing: 
export type DBConnection = {
  db: Knex; // PostgreSQL connection
  kv: RedisClient; // Redis connection
  paymentDB?: Knex; // Optional separate payment DB
};

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Database Access Patterns

  • Knex Queries: Use this.connector.db(tableName) for database access
  • Multi-tenancy: Always filter by shop_id or merchant_id
  • Transactions: Use Knex transactions for complex operations
  • Connection Pooling: Automatic connection management

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Authentication & Middleware

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Request Context

Authentication middlewares populate request objects with user context: 
// Available on authenticated requests
req.currentUser; // User data (excluding sensitive fields)
req.merchant_id; // Merchant ID from headers
req.device_id; // Device ID from headers

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Authentication Middleware

import { authenticateUser, authenticateAdmin } from "core/auth/middlewares";

// In routes.ts
routes.use("*", authenticateUser(db)); // For user endpoints
routes.use("*", authenticateAdmin(db)); // For admin endpoints

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Authorization

Role-based access control using user context: 
// Check user roles
if (!req.currentUser.is_super) {
  throw new CustomError("FORBIDDEN", "Super admin required");
}

// Check specific roles
if (!req.currentUser.roles.includes("merchant_manager")) {
  throw new CustomError("FORBIDDEN", "Insufficient permissions");
}