Using Mongoose in Express Routes

A persistent CRUD API

Remember the Express CRUD API that used an array? Now we replace the array with real database calls through a Mongoose model. The routes look almost the same — but the data is permanent.

const express = require("express");
const Task = require("./models/Task");   // a Mongoose model
const router = express.Router();

// READ all
router.get("/", async (req, res, next) => {
  try {
    const tasks = await Task.find();
    res.json(tasks);
  } catch (err) { next(err); }
});

// CREATE
router.post("/", async (req, res, next) => {
  try {
    const task = await Task.create({ text: req.body.text });
    res.status(201).json(task);
  } catch (err) { next(err); }
});

// DELETE
router.delete("/:id", async (req, res, next) => {
  try {
    await Task.findByIdAndDelete(req.params.id);
    res.json({ message: "Deleted" });
  } catch (err) { next(err); }
});

module.exports = router;

Each route is an async function so it can await the database. The GET / handler calls await Task.find() to load every task and sends them back as JSON. The POST / handler reads req.body.text (what the client sent), await Task.create({...}) saves a new task, and replies with status 201 (“Created”) plus the new task. The DELETE /:id handler reads the id from the URL (req.params.id), removes that task, and replies with a confirmation message. Every handler is wrapped in try/catch, and on any error it calls next(err) to hand the problem to the central error handler.

Here is the full request → response flow for one of these routes, end to end:

1. The client (browser or React app) sends an HTTP request, e.g. POST / with a JSON body.
2. Express matches the URL and method to the right route handler.
3. express.json() middleware has already parsed the body, so req.body.text is ready to use.
4. The handler awaits a Mongoose call (Task.create(...)) which writes to MongoDB.
5. MongoDB stores the document permanently and returns it (with its new _id).
6. The handler sends a response — res.status(201).json(task) — back to the client.
7. If anything throws, try/catch passes the error to next(err) and the error handler replies instead.