Project: Build Course Enrollment API

Project scope

Create a production-style backend service for course enrollment with users, courses, and enrollments resources. Include validation, auth middleware, and persistent storage integration.

Milestone checklist

• Scaffold Express app with modular routes and controllers.
• Implement CRUD endpoints for users and courses.
• Create enrollment endpoint with duplicate-enrollment guard.
• Add pagination, filtering, and basic rate limiting.
• Write API tests for success and failure scenarios.

app.post("/api/enrollments", async (req, res, next) => {
  try {
    const { userId, courseId } = req.body;
    // 1) validate payload
    // 2) ensure user and course exist
    // 3) prevent duplicate enrollment
    // 4) insert enrollment row/document
    res.status(201).json({ message: "Enrollment created" });
  } catch (error) {
    next(error);
  }
});