Django's forms.Form vs forms.ModelForm - django

Question

Could anyone explain to me similarities and differences of Django's forms.Form & forms.ModelForm?

Answer 1

Forms created from forms.Form are manually configured by you. You're better off using these for forms that do not directly interact with models. For example a contact form, or a newsletter subscription form, where you might not necessarily be interacting with the database.
Where as a form created from forms.ModelForm will be automatically created and then can later be tweaked by you. The best examples really are from the superb documentation provided on the Django website.
forms.Form:
Documentation: Form objects
Example of a normal form created with forms.Form:
from django import forms
class ContactForm(forms.Form):
subject = forms.CharField(max_length=100)
message = forms.CharField()
sender = forms.EmailField()
cc_myself = forms.BooleanField(required=False)
forms.ModelForm:
Documentation: Creating forms from models
Straight from the docs:
If your form is going to be used to
directly add or edit a Django model,
you can use a ModelForm to avoid
duplicating your model description.
Example of a model form created with forms.Modelform:
from django.forms import ModelForm
from . import models
# Create the form class.
class ArticleForm(ModelForm):
class Meta:
model = models.Article
This form automatically has all the same field types as the Article model it was created from.

Answer 2

The similarities are that they both generate sets of form inputs using widgets, and both validate data sent by the browser. The differences are that ModelForm gets its field definition from a specified model class, and also has methods that deal with saving of the underlying model to the database.

Answer 3

Here's how I'm extending the builtin UserCreationForm myapp/forms.py:
from django import forms
from django.contrib.auth.forms import UserCreationForm
class RegisterForm(UserCreationForm):
first_name = forms.CharField(max_length=30)
last_name = forms.CharField(max_length=30)
email = forms.CharField(max_length=75)
class Meta(UserCreationForm.Meta):
fields = ('username','first_name','last_name', 'email')

Answer 4

The difference is simple, ModelForm serves to create the form of a Model.
meaning that Model is designed to create kind of schema of your table where you will save data from form submission and ModelForm simply creates a form of the model (from the schema of the table)
# This creates a form from model Article
class ArticleForm(ModelForm):
class Meta:
model = Article
fields = ['pub_date', 'headline', 'content', 'reporter']
Form is a common form that is unrelated to your database (model ).
# A simple form to display Subject and Message field
class ContactForm(forms.Form):
subject = forms.CharField(max_length=100)
message = forms.CharField(widget=forms.Textarea)
To say in other words,
If you have a model in your app and you want to create a Form to enter data in that model (and by it to a db) use forms.ModelForm
If you simple want to create a form using django use form.Form
But you can also use this together:
from django import forms
# A simple form to display Subject and Message field
class ContactForm(forms.ModelForm):
subject = forms.CharField(max_length=100)
message = forms.CharField(widget=forms.Textarea)
class Meta:
model = Contact #when you have this model
fields = [
'subject',
'message',
]