Skip to content

2-routing.md

Latest commit

 

History

History
120 lines (81 loc) · 4.03 KB

2-routing.md

File metadata and controls

120 lines (81 loc) · 4.03 KB

Checkpoint 2: Routing

New Routes

First, update the "home_routes.py" file to define another route there:

# web_app/routes/home_routes.py

# ...

@home_routes.route("/hello")
def hello_world():
    print("HELLO...")
    
    # if the request contains url params, for example a request to "/hello?name=Harper"
    # the request object's args property will hold the values in a dictionary-like structure
    url_params = dict(request.args)
    print("URL PARAMS:", url_params) #> can be empty like {} or full of params like {"name":"Harper"}
    
    # get a specific key called "name" if available, otherwise use some specified default value
    # see also: https://www.w3schools.com/python/ref_dictionary_get.asp
    name = url_params.get("name") or "World"
    
    message = f"Hello, {name}!"
    return message
    #return render_template("hello.html", message=message)

Next, inside the "routes" directory, create new files called "book_routes.py" and "weather_routes.py", and place the following contents inside, respectively:

# web_app/routes/book_routes.py

from flask import Blueprint, jsonify

book_routes = Blueprint("book_routes", __name__)

@book_routes.route("/api/books")
@book_routes.route("/api/books.json")
def list_books():
    print("BOOKS...")
    books = [
        {"id": 1, "title": "Book 1", "year": 1957},
        {"id": 2, "title": "Book 2", "year": 1990},
        {"id": 3, "title": "Book 3", "year": 2031},
    ] # some dummy / placeholder data
    return jsonify(books)

@book_routes.route("/api/books/<int:book_id>")
@book_routes.route("/api/books/<int:book_id>.json")
def get_book(book_id):
    print("BOOK...", book_id)
    book = {"id": book_id, "title": f"Example Book", "year": 2000} # some dummy / placeholder data
    return jsonify(book)
# web_app/routes/weather_routes.py

from flask import Blueprint, request, jsonify

from app.weather_service import get_hourly_forecasts

weather_routes = Blueprint("weather_routes", __name__)

@weather_routes.route("/api/weather/forecast.json")
def weather_forecast_api():
    print("WEATHER FORECAST (API)...")
    
    url_params = dict(request.args)
    print("URL PARAMS:", url_params)

    country_code = url_params.get("country_code") or "US"
    zip_code = url_params.get("zip_code") or "20057"

    results = get_hourly_forecasts(country_code=country_code, zip_code=zip_code)
    if results:
        return jsonify(results)
    else:
        return jsonify({"message":"Invalid Geography. Please try again."}), 404

Finally, to let our app know about these new routes, let's un-comment the related "import" and "register" lines from the web app's "__init__.py" file.

Handling URL Parameters

Restart the server, and visit the following URLs in the browser. Notice we are now passing an optional URL parameter called "name" along with our requests:

FYI: the %20 character acts as a space character in the URL params

Review the code that handles the "hello" route. Notice the "hello" route referencing the request object from Flask, specifically looking at its args property (i.e. request.args), a dictionary-like object, to access the URL params.

Nice, our app is dynamically handling different URL parameters!

Responding with JSON

Finally, visit the following urls in the browser:

Review the code that handles these "book" routes. Notice how we are using the jsonify method from Flask to convert a Python list or dictionary to a JSON response.

Wow, we've just made our own JSON API!

Before moving on, make a commit with a message like "Web App Routing".