Checking Input

Part of the Forms section of Coddy's Django journey. Lesson 4 of 20.

Send the form with an empty title and the board gets an event with no name. Anything can arrive in request.POST, so a view checks it before saving.

When the input is wrong, the view saves nothing and does not redirect: it renders the form page again with a message. A table booking form that takes 1 to 8 guests:

guests = request.POST["guests"]
if not guests.isdigit() or not 1 <= int(guests) <= 8:
    problem = "Choose between 1 and 8 guests."
    return render(request, "tables/book.html", {"problem": problem})
Booking.objects.create(guests=int(guests))

The check comes before create(): once the row is saved, the message is too late. For text, .strip() removes the spaces at both ends, so a title of only spaces becomes empty. The template shows the message only when there is one:

{% if problem %}
<p class="warning">{{ problem }}</p>
{% endif %}

Challenge

Easy

Refuse an event without a title:

When the title is empty or only spaces, new_event shows the form page again with Please give the event a title. above the form, and saves nothing.
A form with a title still adds the event and redirects to it.

Press Run and send the form with a title of three spaces.

Try it yourself

from django.shortcuts import get_object_or_404, redirect, render

from .models import Event


def event_list(request):
    q = request.GET.get("q", "")
    events = Event.objects.all()
    if q:
        events = events.filter(title__icontains=q)
    return render(request, "events/event_list.html", {"events": events, "q": q})


def event_detail(request, pk):
    event = get_object_or_404(Event, pk=pk)
    return render(request, "events/event_detail.html", {"event": event})


def new_event(request):
    if request.method == "POST":
        event = Event.objects.create(
            title=request.POST["title"],
            date=request.POST["date"],
            place=request.POST["place"],
        )
        return redirect("events:detail", pk=event.pk)
    return render(request, "events/new_event.html")