DJANGO - local variable 'form' referenced before assignment

Question

I'm trying to make a form get information from the user and use this information to send a email. Here's my code:

#forms.py
from django import forms

class ContactForm(forms.Form):
    nome = forms.CharField(required=True)
    email = forms.EmailField(required=True)
    msg = forms.CharField(
        required=True,
        widget=forms.Textarea
    )

#views.py
from django.shortcuts import render, redirect, get_object_or_404, HttpResponseRedirect, render_to_response
from django.core.mail import send_mail
from .forms import ContactForm

def contato(request):
    form_class = ContactForm
    if request.method == 'POST':
        form = form_class(request.POST)
        if form.is_valid():
            nome = request.POST.get('nome')
            email = request.POST.get('email')
            msg = request.POST.get('msg')

            send_mail('Subject here', msg, email, ['[email protected]'], fail_silently=False)
            return HttpResponseRedirect('blog/inicio')
    return render(request, 'blog/inicio.html', {'form': form})


#contato.html
{% extends "blog/base.html" %}
{% block content %}

                    <form role="form" action="" method="post">
                        {% csrf_token %}
                        {{ form.as_p }}
                        <button type="submit">Submit</button>
                    </form>
{% endblock %}

and when I try to enter in contact page I get this error:

local variable 'form' referenced before assignment

It is saying tha the error is in this line of views.py:

return render(request, 'blog/inicio.html', {'form': form})

I'm a little new on Django, can you please help me?

Solution 1

You define the form variable in this if request.method == 'POST': block. If you access the view with a GET request form gets not defined. You should change the view to something like this:

def contato(request):
    form_class = ContactForm
    # if request is not post, initialize an empty form
    form = form_class(request.POST or None)
    if request.method == 'POST':

        if form.is_valid():
            nome = request.POST.get('nome')
            email = request.POST.get('email')
            msg = request.POST.get('msg')

            send_mail('Subject here', msg, email, ['[email protected]'], fail_silently=False)
            return HttpResponseRedirect('blog/inicio')
    return render(request, 'blog/inicio.html', {'form': form})

Solution 2

The Django docs handle this, but slightly differently from the other answers. See https://docs.djangoproject.com/en/dev/topics/forms/#using-a-form-in-a-view

Using an else, if the request is not POST then create the blank form. The below is pasted directly from the docs.

def get_name(request):
    # if this is a POST request we need to process the form data
    if request.method == 'POST':
        # create a form instance and populate it with data from the request:
        form = NameForm(request.POST)
        # check whether it's valid:
        if form.is_valid():
            # process the data in form.cleaned_data as required
            # ...
            # redirect to a new URL:
            return HttpResponseRedirect('/thanks/')

    # if a GET (or any other method) we'll create a blank form
    else:
        form = NameForm()

    return render(request, 'name.html', {'form': form})