Python Coding and Algorithmic Logic for Students in Chiang Mai

1. From Scripts to a Local Web Server

This lesson turns Flask theory into a running app: install the package, write a tiny route, and open the response in a browser.

2. Environment Setup

• Confirm Python: python --version
• Use VS Code (or similar) with the Python extension and a project folder such as my_flask
• Install Flask: pip install flask or python -m pip install flask

3. hello.py

from flask import Flask

app = Flask(__name__)

@app.route("/")
def home():
    return "Hello Flask, your ML API is alive!"

if __name__ == "__main__":
    app.run(debug=True, use_reloader=False)

4. Code Anatomy

• from flask import Flask — import the framework class
• app = Flask(__name__) — create the application object
• @app.route("/") — map the root URL to home()
• app.run(debug=True, ...) — start the development server with the interactive debugger

Keep debug=True while learning; turn it off for public deployment so error pages do not expose internals.

5. Run and Open in a Browser

python hello.py

The terminal shows a local URL such as http://127.0.0.1:5000. The IP is localhost (your machine); the port (often 5000) is where Flask listens. Paste that URL into a browser to see the hello message.