Django ModelForm – Create form from Models

Django ModelForm is a class that is used to directly convert a model into a Django form. If you’re building a database-driven app, chances are you’ll have forms that map closely to Django models. For example, a User Registration model and form would have same quality and quantity of model fields and form fields. So instead of creating a redundant code to first create a form and then map it to the model in a view, we can directly use ModelForm. It takes as argument the name of the model and converts it into a Django Form. Not only this, ModelForm offers a lot of methods and features which automate the entire process and help remove code redundancy.

To explain the working of the project, we will use project mcatutorials, create a model and map it to Django forms.

Refer to the following articles to check how to create a project and an app in Django.

• How to Create a Basic Project using MVT in Django?
• How to Create an App in Django ?

Now when we have our project ready, create a model in mcatutorials/models.py,

# import the standard Django Model 
# from built-in library 
from django.db import models 
   
# declare a new model with a name "McatutorialsModel" 
class McatutorialsModel(models.Model): 
        # fields of the model 
    title = models.CharField(max_length = 200) 
    description = models.TextField() 
    last_modified = models.DateTimeField(auto_now_add = True) 
    img = models.ImageField(upload_to = "images/") 
   
        # renames the instances of the model 
        # with their title name 
    def __str__(self): 
        return self.title

Now, run following commands to create the model,

Python manage.py makemigrations
Python manage.py migrate

We can check that model has been successfully created at

http://127.0.0.1:8000/admin/mca/mcatutorials/add/,

To create a form directly for this model, dive into mcatutorials/forms.py and Enter following code,

# import form class from django 
from django import forms 
  
# import McatutorialsModel from models.py 
from .models import McaModel 
  
# create a ModelForm 
class McaForm(forms.ModelForm): 
    # specify the name of model to use 
    class Meta: 
        model = McaModel 
        fields = "__all__"

This form takes two arguments fields or exclude>.

• fields – It is strongly recommended that you explicitly set all fields that should be edited in the form using the fields attribute. Failure to do so can easily lead to security problems when a form unexpectedly allows a user to set certain fields, especially when new fields are added to a model. Depending on how the form is rendered, the problem may not even be visible on the web page. Set the fields attribute to the special value ‘__all__’ to indicate that all fields in the model should be used.
• exclude – Set the exclude attribute of the ModelForm’s inner Meta class to a list of fields to be excluded from the form. For example:

class PartialAuthorForm(ModelForm):
    class Meta:
        model = Author
        exclude = ['title']

Finally, to complete our MVT structure, create a view that would render the form and directly save it to the database. In mca/views.py,

from django.shortcuts import render 
from .forms import McaForm 
  
def home_view(request): 
    context ={} 
  
    # create object of form 
    form = McaForm(request.POST or None, request.FILES or None) 
      
    # check if form data is valid 
    if form.is_valid(): 
        # save the form data to model 
        form.save() 
  
    context['form']= form 
    return render(request, "home.html", context)

Everything set, Now visit http://127.0.0.1:8000/,



Now you can see that every model field is mapped into a form field and displayed correspondingly. Field mappings are discussed later in this article. So now let’s try entering data into form and check if it gets saved into the database.



Hit submit and Bingo the form gets saved automatically to database. We can verify it at http://localhost:8000/admin/mca/mcatutorials/.

Field types

The generated Form class will have a form field for every model field specified, in the order specified in the fields attribute. Each model field has a corresponding default form field. For example, a CharField on a model is represented as a CharField on a form. A model ManyToManyField is represented as a MultipleChoiceField. Here is the full list of conversions:

MODEL FIELD	FORM FIELD
AutoField	Not represented in the form
BigAutoField	Not represented in the form
BigIntegerField	IntegerField with min_value set to -9223372036854775808 and max_value set to 9223372036854775807.
BinaryField	CharField, if editable is set to True on the model field, otherwise not represented in the form.
BooleanField	BooleanField, or NullBooleanField if null=True.
CharField	CharField with max_length set to the model field’s max_length and empty_value set to None if null=True.
DateField	DateField
DateTimeField	DateTimeField
DecimalField	DecimalField
DurationField	DurationField
EmailField	EmailField
FileField	FileField
FilePathField	FilePathField
FloatField	FloatField
ForeignKey	ModelChoiceField
ImageField	ImageField
IntegerField	IntegerField
IPAddressField	IPAddressField
GenericIPAddressField	GenericIPAddressField
ManyToManyField	ModelMultipleChoiceField
NullBooleanField	NullBooleanField
PositiveIntegerField	IntegerField
PositiveSmallIntegerField	IntegerField
SlugField	SlugField
SmallAutoField	Not represented in the form
TextField	CharField with widget=forms.Textarea
TimeField	TimeField
URLField	URLField

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