RESTful APIs are a way for different software systems to communicate over the internet using standard HTTP methods such as GET, POST, PUT, and DELETE. They provide a set of rules that allow programs to exchange data in a structured way, typically using JSON.

In Go, RESTful APIs are commonly built using web frameworks such as Fiber, Gin, or the standard net/http package. For this lesson, we will use the Fiber web framework because it is simple, fast, and inspired by Express.js, making it familiar for developers coming from Node.js.

To get started with Fiber, you can install it using the following command:

Fiber makes it easy to define routes, handle requests, and return JSON responses, which is ideal for building RESTful APIs.

This code creates a new Fiber app and starts the server on port 3000. The app will handle all incoming HTTP requests.

Install the session middleware with:

This code sets up session management using cookies. The middleware will automatically handle session creation, retrieval, and storage for each request.

This configuration allows the server to serve static files (CSS, JavaScript, images) from the "static" directory. This is essential for creating a web interface for your tutor service.

In your main function:

This code creates a controller that will handle HTTP requests and delegate business logic to the tutor service. The controller follows the dependency injection pattern, making it easier to test and maintain.

This helper method ensures each student has a unique identifier across requests, which is crucial for maintaining conversation context.

This handler serves the main page of the tutor application. It ensures a student ID exists in the session and renders a welcome message. This is the entry point for users accessing your tutor service.

This endpoint creates a new tutoring session for the student. It returns a session ID that will be used for subsequent queries. This is typically called when a student starts a new conversation with the tutor.

The CreateSession method typically returns:

• A response object containing the new session ID
• An HTTP status code (200 for success, 4xx/5xx for errors)

This endpoint processes student queries. It validates the input, calls the tutor service to process the query, and returns the response. This is the core functionality of the tutor service, where students ask questions and receive personalized answers.

The SendQuery method typically returns:

• A response object containing the tutor's answer
• An HTTP status code (200 for success, 4xx/5xx for errors)

Fiber allows you to handle errors by returning appropriate status codes and JSON responses directly in your handler functions. Use early returns and consistent error response structures as shown above.

Error handling is implemented directly in each handler with appropriate HTTP status codes and error messages. This approach provides clear feedback to clients about what went wrong and how to fix it.

This command compiles and runs your Go application. The server will start listening on port 3000, ready to handle requests from students.

1. Access the Index Route (/): The student visits the root URL, which ensures a session is established and the student receives a welcome message.
2. Create a Tutoring Session (/api/create_session): The student sends a POST request to create a new tutoring session. The server responds with a unique session ID, which is used for subsequent queries.
3. Send a Query (/api/send_query): The student sends a POST request with the session ID and their question. The server processes the query and responds with the tutor's answer, maintaining the conversation context using the session.

Sessions are managed using cookies and the session middleware, ensuring each student's interactions are kept separate and persistent across requests.

In this lesson, we built a RESTful API for our personal tutor service using Go and the Fiber web framework. We set up a web server, defined routes for tutoring operations, managed sessions, and explored how the TutorController integrates with session management and request handling in Go. This lesson brings together all the components we've developed so far into a functional web application that can deliver personalized academic support.

As you move on to the practice exercises, experiment with the Go API and reinforce the concepts covered in this lesson. This hands-on practice will prepare you for further development and exploration of additional Go web development and RESTful API concepts. Keep up the great work, and I look forward to seeing your progress!