Django form view

Prerequisites

ways to send information to server

  • Can send the data in HTTP headers
  • Can send the data in HTTP request params
  • Can send the data in HTTP request body.

What is a form?

  • A form is used to send the information to the server
  • GET and POST are the only HTTP methods to use when dealing with forms.

Django forms

  • Django provides a way to create the form fields in a pythonic way with/without form context
  • Django forms validates the data when a data is submitted to the server.
  • Django forms also helpful in rendering the error or validation messages if submitted data is not in the required format.

django contact form

  • Let's create a simple django contact form.
  • Create a forms.py file in the django app my_app and add the below code.

my_app/forms.py

from django import forms

class ContactForm(forms.Form):
    first_name = forms.CharField(max_length=10)
    last_name = forms.CharField(max_length=10)
    email = forms.EmailField(max_length=100)

django form as HTML

  • Can generate HTML from the above django form.
  • Now, open django shell generate HTML from django form with below code.
form = ContactForm()
print(form.as_div())
  • It will generate below HTML
<div>
  <label for="id_first_name">First name:</label>
  <input type="text" name="first_name" maxlength="10" required id="id_first_name">
</div>
<div>
  <label for="id_last_name">Last name:</label>
  <input type="text" name="last_name" maxlength="10" required id="id_last_name">
</div>
<div>
  <label for="id_email">Email:</label>
  <input type="email" name="email" maxlength="10" required id="id_email">
</div>
  • we can use same HTML if the django template just like {{ form.as_div }}
  • similarly, we can use other form methods like form.as_p(), form.as_ul() and form.as_table()
  • we render the template with form fields for GET request.

Django Form for data validation

  • Django forms can be used to validate the form data as well.
  • Look at the below code.
data = {}
form = ContactForm(data)
print(form.is_valid())
# output: False
print(form.errors)
# output: <ul class="errorlist"><li>first_name<ul class="errorlist"><li>This field is required.</li></ul></li><li>last_name<ul class="errorlist"><li>This field is required.</li></ul></li><li>email<ul class="errorlist"><li>This field is required.</li></ul></li></ul>
print(form.errors.as_json())
# output: {"first_name": [{"message": "This field is required.", "code": "required"}], "last_name": [{"message": "This field is required.", "code": "required"}], "email": [{"message": "This field is required.", "code": "required"}]}
  • form.is_valid() method is used to check whether the form data is valid or not.

  • form.errors, form.errors.as_json() are used for form errors.

  • Let's use the valid data

data = {"email": "john@example.com", "first_name": "John", "last_name": "Doe"}
form = ContactForm(data)
print(form.is_valid())
# output: True
print(form.cleaned_data)
# output: {'first_name': 'John', 'last_name': 'Doe'}
  • form.cleaned_data returns the validated data.

Django form view

function based form view

  • we can use the forms with function based views for simple functionality.
  • lets write a simple form view to get the contact information.
  • we will be using the ContactForm mentioned in this article.
  • look at the below code
from django.http import HttpResponse
from django.shortcuts import render
from my_app.forms import ContactForm

def my_form_view(request):
    if request.method.lower() == "POST":
        form = ContactForm(request.POST)
        if form.is_valid():
            data = form.cleaned_data
            print(data)
            return HttpResponse("successfully submitted the form")
    else:
        form = ContactForm()
    context = {"form": form}
    return render(request, 'form_template.html', context)

form_template.html

<form action="" method="POST" enctype="multipart/form-data">
    {% csrf_token %}
    {{ form.as_table }}
    <input type="submit" value="submit" />
</form>

class based form view

from django.http import HttpResponse
from django.views.generic.edit import FormView
from my_app.forms import ContactForm

class MyFormView(FormView):
    template_name='form_template.html'
    form_class=ContactForm

    def form_valid(self, form):
      data = form.cleaned_data
      print(data)
      return HttpResponse("successfully submitted the form")
  • FormView is generic class provided by django.
  • It provides the generic functionality for form views.
  • It comes with methods like form_valid and form_invalid to handle the requests.
  • Only use it if your functionality matches with FormView implementation.

configure urls

  • open my_app/urls.py and add below code to it.
from django.urls import path
from my_app import views

urlpatterns = [
    # ...
    path('fbv_form_view', views.my_form_view, name='fmy_form_view'),
    path('cbv_form_view', views.MyFormView.as_view(), name='cmy_form_view'),
    # ...
]

References