Lunchtime, Room 12
" @app.route("/about") def about(): return "Everyone is welcome.
" app.run() ``` :::keep-together **Someone visits /about. What does the site send back?** ☐ Both pages, one after the other ☐ Nothing: about() is never called ☐ A page with the heading About and "Everyone is welcome." ☐ The Chess club page My prediction, and why: {{lines-3}} ::: :::teacher-note **What happens:** The About page. @app.route("/about") joins the address /about to the function about(), so Flask calls it and sends back the HTML it returns. ::: ## Run Run the program in the tutorial. Was your prediction right? What was different? {{lines-2}} ## Investigate ```python from flask import Flask app = Flask(__name__) @app.route("/") def home(): page = "Lunchtime on Tuesdays, Room 12.
" page = page + "" return page @app.route("/about") def about(): return "Everyone is welcome, from beginners to champions.
" app.run() ``` :::keep-together ### An address with no route **What does a visitor see at /missing?** ☐ An empty page ☐ Python stops with an error ☐ The home page ☐ A Not Found page (error 404): no route matches that address ::: :::teacher-note **Answer:** A Not Found page (error 404): no route matches that address Flask looks for a route that matches the address. With none, it sends back the standard 404 Not Found page, as every website does. ::: :::keep-together ### Building the page **home() builds page with page = page + ... three times. What is the page?** ☐ Three separate pages ☐ Only the last part ☐ A list of three lines ☐ One piece of HTML text, joined from three parts ::: :::teacher-note **Answer:** One piece of HTML text, joined from three parts page is text; each line adds more HTML to the end. The browser shows the whole thing as one page. ::: :::keep-together ### Spot the bug **Clicking "About the club" shows Not Found, though about() is written. Click the line where the problem is.** ``` 1 from flask import Flask 2 3 app = Flask(__name__) 4 5 6 @app.route("/") 7 def home(): 8 return "Everyone is welcome.
" 13 14 15 app.run() ``` Line: {{field-15}} Why is it wrong? {{lines-2}} ::: :::teacher-note **Answer:** line 11 about() has no @app.route("/about") above it, so no address leads to it. A function only becomes a page when a route points to it. ::: :::typical ## Modify **A results page.** Add a `/results` page with a small table of players and their wins (as on the club page in HTML & CSS), and a link to it from the home page. **A visit counter.** Count the visits to the home page and show the number on it. Visit it a few times, then press **Run** again: what happens to the count? Work in the tutorial. Plan first: what will you change, and how will you test it? {{box-4}} :::teacher-note **One possible solution.** Other correct programs are fine; check that the program runs and does what the task asks. **A results page:** ```python from flask import Flask app = Flask(__name__) @app.route("/") def home(): page = "Lunchtime on Tuesdays, Room 12.
" page = page + "" page = page + "" return page @app.route("/about") def about(): return "Everyone is welcome, from beginners to champions.
" @app.route("/results") def results(): return "| Player | Wins |
|---|---|
| Ada | 5 |
| Sam | 4 |
Lunchtime on Tuesdays, Room 12.
" page = page + "" page = page + "This page has been visited " + str(visits) + " times.
" return page @app.route("/about") def about(): return "Everyone is welcome, from beginners to champions.
" app.run() ``` ::: ::: ## Make: your own site Make a small site for a club, a team or a hobby: a home page and at least two more pages, each linking back home. Work in the tutorial. Plan first: what will you change, and how will you test it? {{box-4}} :::teacher-note **One possible solution.** Other correct programs are fine; check that the program runs and does what the task asks. ```python from flask import Flask app = Flask(__name__) @app.route("/") def home(): return "