Query Strings

Part of the Django Basics section of Coddy's Django journey. Lesson 8 of 23.

The order page always says medium. The size a customer picks can travel in the address, after a question mark: /order/?size=large.

That part is the query string: name=value pairs joined by &. It is not part of the route, so path("search/", ...) matches /search/?q=cake too. The view reads the pairs from request.GET, which works like a dictionary:

def search(request):
    word = request.GET.get("q", "")
    if len(word) > 30:
        word = word[:30]
    return HttpResponse(f"Results for {word}")

.get() takes a default for a missing name; request.GET["q"] would crash instead. Every value arrives as text, and anyone can type anything after the ?, so check a value before you use it.

Challenge

Easy

Make /order/ read the size from the query string:

?size=large says You ordered a large coffee., and the same for small and medium;
no size, or one the café does not sell like huge, orders a medium coffee.

Press Run: the preview opens /order/?size=large.

Try it yourself

from django.http import HttpResponse

DRINKS = {
    "espresso": {"name": "Espresso", "price": 2.5, "description": "A short, strong shot of coffee."},
    "latte": {"name": "Latte", "price": 3.5, "description": "Espresso with lots of steamed milk."},
    "flat-white": {"name": "Flat White", "price": 3.75, "description": "Espresso with a thin layer of silky milk."},
    "hot-chocolate": {"name": "Hot Chocolate", "price": 3, "description": "Dark chocolate melted into warm milk."},
}


def home(request):
    return HttpResponse("<h1>Welcome to Corner Café</h1><p>Fresh coffee and cake every day.</p>")


def about(request):
    return HttpResponse("Corner Café opened in 2026.")


def hours(request):
    return HttpResponse("Open every day from 8:00 to 18:00.")


def contact(request):
    return HttpResponse("Write to us at hello@cornercafe.example.")


def table(request, number):
    return HttpResponse(f"<h1>Table {number}</h1>")


def drink(request, slug):
    item = DRINKS[slug]
    return HttpResponse(f"<h1>{item['name']}</h1><p>{item['description']}</p>")


def order(request):
    size = "medium"
    return HttpResponse(f"You ordered a {size} coffee.")