CHEGG BACKED DEV

Backend development reference

Well-structured backends separate concerns: routers define URLs, controllers translate HTTP to application calls, services own data access, and middleware handles cross-cutting behavior (validation, 404, errors). Study these patterns to keep files small, testable, and aligned with REST conventions.

Controller (.controller.js)

Controllers sit between HTTP and your domain: they read req.params, req.query, and req.body, call services, and send JSON with the right status code. See Route parameters and Query string sections for the distinction. Keep controllers thin (no Knex) and use next(err) for errors.

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How to use a controller module — Intermediate

Server Architecture / Routes Controller (.controller.js)
Keep route files thin by delegating request logic to controller functions.
Learn: A controller module exports functions the router references by name. Each function receives (req, res, next), calls the service layer, and shapes the HTTP response. The router never calls Knex; the controller never defines URL paths—that division is the core of the Organizing Express pattern.

Supplementary examples

Thin controller calling a service

async function list(req, res, next) {
  try {
    const pastes = await service.listByUser(req.params.userId);
    res.json({ data: pastes });
  } catch (err) {
    next(err);
  }
}

Set status for create

async function create(req, res, next) {
  try {
    const paste = await service.create(req.body);
    res.status(201).json({ data: paste });
  } catch (err) {
    next(err);
  }
}

Course example

// pastes.controller.js — HTTP in/out; calls service for data
const service = require("./pastes.service");

async function list(req, res, next) {
  try {
    const pastes = await service.list(req.params.userId);
    res.json({ data: pastes });
  } catch (err) {
    next(err);
  }
}

async function create(req, res, next) {
  try {
    const paste = await service.create(req.params.userId, req.body);
    res.status(201).json({ data: paste });
  } catch (err) {
    next(err);
  }
}

module.exports = { list, create };

Additional references & examples