Django Formsets

Implementing Django Formsets

Project Setup

Before learning about formsets, let us set up our Django example project. Simply run the following commands on the terminal to make a test project.

django-admin startproject testProject
cd testProject
django-admin startapp testApp 

Doing this, we would have a new Django project called “testProject” containing an app called “testApp.” We should have the following directory structure:

If there is an issue while setting up the project, head over to this link to set up the project. 

Creating our Formset

First, let us make a formset consisting of just one form. To do so, create a forms.py file in the testApp directory and add the following code. 

from django import forms
  
# Creating a form
class blogForm(forms.Form):
    blog = forms.CharField()
    author = forms.CharField()

You can also try this code with Online Python Compiler

Run Code

The above code creates a simple form that has two fields. The left side of the statement names the field, while the right side of the statement showcases the input type. In this form, there are two fields called blog and author. 

Now, we need to create a formset out of this form. To do so, add the following code to the views.py file in the testApp directory. 

from django.shortcuts import render
from .forms import testForm


# Importing the required formset class from the django.forms class
from django.forms import formset_factory


def formset_view(request):
    context ={}
    blogFormSet = formset_factory(blogForm) // Creates a formset
    formset = blogFormSet()
    context['formset']= formset
    return render(request, "testApp/home.html", context)

You can also try this code with Online Python Compiler

Run Code

With the view complete, let us complete our architecture for this form by creating the template for this formset. In the testApp subdirectory of the templates directory, create a file called home.html and add the following code.

<form method="POST" enctype="multipart/form-data">
    {{ formset.as_p }}
    <input type="submit" value="Submit">
</form>

You can also try this code with Online Python Compiler

Run Code

Let us head to http://localhost:8000/ to check our form.

Now our form is complete and ready. 

Formsets with Multiple Forms

As discussed earlier, the most extensive functionality of formsets is their ability to create and handle multiple forms at once. This is done using the extra attribute of formsets. For example, if we need to make three instances of the form, we can modify the code in our views.py file as follows.

from django.shortcuts import render
from .forms import testForm


# Importing the required formset class from the django.forms class
from django.forms import formset_factory


def formset_view(request):

    context ={}

    blogFormSet = formset_factory(blogForm, extra=3) // Creates a formset of 3 forms.
    formset = blogFormSet()


    context['formset']= formset
    return render(request, "testApp/home.html", context)

You can also try this code with Online Python Compiler

Run Code

The extra attribute is assigned the value of the number of instances we want of the form. We can do so for different forms as well.

Let us head to http://localhost:8000/ to check how this changes our form.

Now we have three forms in our formset. We need to understand that it is easy to create multiple forms; the main challenge arises in handling their data correctly in the backend. This challenging task is made easy using Django formsets. Let us see how we can handle data efficiently. For this example, we would print the data on our server terminal to see how the data is being processed. 

Add the data management function to manage formset data in the template code.

<form method="POST" enctype="multipart/form-data">
    
    <!-- Management data of formset -->
    {{ formset.management_data }}
    <!-- Using the formset -->
    {{ formset.as_p }}
    
    <input type="submit" value="Submit">
</form>

You can also try this code with Online Python Compiler

Run Code

To get the data printed on the terminal, make the following amendment to the views.py file.

from django.shortcuts import render
from .forms import testForm


# Importing the required formset class from the django.forms class
from django.forms import formset_factory


def formset_view(request):


    context ={}


    blogFormSet = formset_factory(blogForm, extra=3) // Creates a formset of 3 forms.
    formset = testFormSet()
            
            if formset.is_valid():
        for form in formset:
            print(form.cleaned_data)


    context['formset']= formset
    return render(request, "testApp/home.html", context)

You can also try this code with Online Python Compiler

Run Code

With this done, our formset is now complete. Let us fill in some dummy data and see how it is sent to the backend. 

Adding dummy data to our formset.

The terminal to view data.

Frequently Asked Questions

1. What are Django formsets?
   A Django formset is a layer of abstraction to work with multiple forms on the same page. It can be best compared to a data grid.
    
2. What is the max number of forms a formset can have?
   Although there is no such limit, we can limit the max number of forms in a formset by using the max_num parameter to formset_factory().

Key Takeaways

This blog looked into the critical aspects of the Django formsets. We created a sample app and project and demonstrated the working of three forms which constituted a formset by printing their output on our terminal. Formsets are an advanced concept and should be used with critical inspection of correct syntax; otherwise, many problems can arise. Continue learning Django and backend web development using this link!