Full CRUD REST API Example

14 min read

Full CRUD REST API Example

A REST API exposes resources over HTTP using the four CRUD operations: Create (POST), Read (GET), Update (PUT/PATCH), and Delete (DELETE). Here is a self-contained in-memory example for a /users resource.

import express from "express";

const app = express();
app.use(express.json());

let users = [
  { id: 1, name: "Alice" },
  { id: 2, name: "Bob" }
];
let nextId = 3;

// READ ALL
app.get("/users", (req, res) => {
  res.json(users);
});

// READ ONE
app.get("/users/:id", (req, res) => {
  const user = users.find(u => u.id === Number(req.params.id));
  if (!user) return res.status(404).json({ error: "Not found" });
  res.json(user);
});

// CREATE
app.post("/users", (req, res) => {
  const user = { id: nextId++, name: req.body.name };
  users.push(user);
  res.status(201).json(user);
});

// UPDATE
app.put("/users/:id", (req, res) => {
  const idx = users.findIndex(u => u.id === Number(req.params.id));
  if (idx === -1) return res.status(404).json({ error: "Not found" });
  users[idx] = { id: Number(req.params.id), name: req.body.name };
  res.json(users[idx]);
});

// DELETE
app.delete("/users/:id", (req, res) => {
  users = users.filter(u => u.id !== Number(req.params.id));
  res.status(204).send();
});

app.listen(3000);

This example is intentionally simple. In a real application you would replace the in-memory array with database calls and add input validation, authentication, and proper error handling.

CPCODELAB students build a version of this pattern in every backend module — it is the skeleton that every more advanced pattern (auth, caching, pagination) is attached to.

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