REST API

RESTful API design for web services.

When to Use

• Web service APIs
• CRUD operations
• Resource-based endpoints
• Stateless communication

Quick Start

// Express REST endpoints
app.get("/api/users", getAllUsers);
app.get("/api/users/:id", getUserById);
app.post("/api/users", createUser);
app.put("/api/users/:id", updateUser);
app.delete("/api/users/:id", deleteUser);

Core Concepts

HTTP Methods

// GET - Retrieve resource
app.get("/api/users/:id", async (req, res) => {
  const user = await db.users.findUnique({ where: { id: req.params.id } });
  if (!user) return res.status(404).json({ error: "User not found" });
  res.json(user);
});

// POST - Create resource
app.post("/api/users", async (req, res) => {
  const user = await db.users.create({ data: req.body });
  res.status(201).json(user);
});

// PUT - Replace resource
app.put("/api/users/:id", async (req, res) => {
  const user = await db.users.update({
    where: { id: req.params.id },
    data: req.body,
  });
  res.json(user);
});

// PATCH - Partial update
app.patch("/api/users/:id", async (req, res) => {
  const user = await db.users.update({
    where: { id: req.params.id },
    data: req.body,
  });
  res.json(user);
});

// DELETE - Remove resource
app.delete("/api/users/:id", async (req, res) => {
  await db.users.delete({ where: { id: req.params.id } });
  res.status(204).send();
});

Status Codes

// 2xx Success
res.status(200).json(data); // OK
res.status(201).json(created); // Created
res.status(204).send(); // No Content

// 4xx Client Error
res.status(400).json({ error: "Bad request" }); // Bad Request
res.status(401).json({ error: "Unauthorized" }); // Unauthorized
res.status(403).json({ error: "Forbidden" }); // Forbidden
res.status(404).json({ error: "Not found" }); // Not Found
res.status(422).json({ error: "Validation failed" }); // Unprocessable

// 5xx Server Error
res.status(500).json({ error: "Internal error" }); // Internal Error

Common Patterns

Pagination

app.get("/api/users", async (req, res) => {
  const page = parseInt(req.query.page as string) || 1;
  const limit = parseInt(req.query.limit as string) || 20;
  const skip = (page - 1) * limit;

  const [users, total] = await Promise.all([
    db.users.findMany({ skip, take: limit }),
    db.users.count(),
  ]);

  res.json({
    data: users,
    meta: {
      page,
      limit,
      total,
      totalPages: Math.ceil(total / limit),
    },
  });
});

Error Handling

app.use((err: Error, req: Request, res: Response, next: NextFunction) => {
  console.error(err);
  res.status(500).json({
    error: "Internal server error",
    message: process.env.NODE_ENV === "development" ? err.message : undefined,
  });
});

Best Practices

Do:

• Use nouns for resources
• Return proper status codes
• Implement pagination
• Version your API

Don't:

• Use verbs in URLs
• Return 200 for errors
• Expose internal errors
• Skip input validation

Troubleshooting

Issue	Cause	Solution
404 on valid route	Wrong method	Check HTTP method
CORS error	Missing headers	Configure CORS
500 error	Unhandled exception	Add error handler

References

• REST API Tutorial
• HTTP Status Codes