Django Formsets

Formsets in a Django is an advanced way of handling multiple forms on a single webpage. In other words, Formsets are a group of forms in Django. One might want to initialize multiple forms on a single page all of which may involve multiple POST requests, for example

from django import forms
class McatutorialsForm(forms.Form):
    title = forms.CharField()
    pub_date = forms.DateField()

Now one might want to permit the user to create articles at once, so if thought in a conventional manner one uses multiple forms and different names for each form to handle data on a single page but this would complicate the code as well as functionality. A formset is a layer of abstraction to work with multiple forms on the same page. It can be best compared to a data grid. Now to create a formset of this

from django.forms import formset_factory
McatutorialsFormSet = formset_factory(McatutorialsForm)

Illustration of Rendering Django Forms Manually using an Example. Consider a project named mcatutorials having an app named mcatutorials.

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 ?

In your mcatutorials app make a new file called forms.py where you would be making all your forms. To create a Django form you need to use Django Form Class. Let’s demonstrate how,

In your forms.py Enter the following,

from django import forms 
  
# create a form 
class McatutorialsForm(forms.Form): 
    title = forms.CharField() 
    description = forms.CharField() 

Let’s explain what exactly is happening, left side denotes the name of the field and to right of it, you define various functionalities of an input field correspondingly. A field’s syntax is denoted as

Field_name = forms.FieldType(attributes)

Now to create a simple formset of this form, move to views.py and create a formset_view as below.

from django.shortcuts import render 
  
# relative import of forms 
from .forms import McatutorialsForm 
  
# importing formset_factory 
from django.forms import formset_factory 
  
def formset_view(request): 
    context ={} 
  
    # creating a formset 
    McatutorialsFormSet = formset_factory(McatutorialsForm) 
    formset = McatutorialsFormSet() 
      
    # Add the formset to context dictionary 
    context['formset']= formset 
    return render(request, "home.html", context) 

To render the formset through HTML, create a html file “home.html”. Now let’s edit templates > home.html

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

All set to check if our formset is working or not let’s visit http://localhost:8000/.

Our formset is working completely. Let’s learn how to modify this formset to use extra features of this formset.

Django formsets are used to handle multiple instances of a form. One can create multiple forms easily using extra attribute of Django Formsets. In mcatutorials/views.py,

from django.shortcuts import render 
  
# relative import of forms 
from .forms import McatutorialsForm 
  
# importing formset_factory 
from django.forms import formset_factory 
  
def formset_view(request): 
    context ={} 
  
    # creating a formset and 5 instances of McatutorialsForm 
    McatutorialsFormSet = formset_factory(McatutorialsForm, extra = 5) 
    formset = McatutorialsFormSet() 
      
    # Add the formset to context dictionary 
    context['formset']= formset 
    return render(request, "home.html", context)

The keyword argument extra makes multiple copies of same form. If one wants to create 5 forms enter extra = 5 and similarly for others. Visit http://localhost:8000/ to check if 5 forms are created.

Creating a form is much easier than handling the data entered into those fields at the back end. Let’s try to demonstrate how one can easily use the data of a formset in a view. When trying to handle formset, Django formsets required one extra argument {{ formset.management_data }}. To know more about Management data, visit Understanding the ManagementForm.

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

Now to check how and what type of data is being rendered edit formset_view to print the data. In mcatutorials/view.py,

from django.shortcuts import render 
  
# relative import of forms 
from .forms import McatutorialsForm 
  
# importing formset_factory 
from django.forms import formset_factory 
  
def formset_view(request): 
    context ={} 
  
    # creating a formset and 5 instances of McatutorialsForm 
    McatutorialsFormSet = formset_factory(McatutorialsForm, extra = 3) 
    formset = McatutorialsFormSet(request.POST or None) 
      
    # print formset data if it is valid 
    if formset.is_valid(): 
        for form in formset: 
            print(form.cleaned_data) 
              
    # Add the formset to context dictionary 
    context['formset']= formset 
    return render(request, "home.html", context) 

Now let’s try to enter data in the formset through http://localhost:8000/

Hit submit and data will be display in command line where server is running. One can use this data in any manner conveniently now.

Formset is advanced stuff which can be used to resolve a number of problems but should be used with correct syntax and field validations otherwise conflicts and errors will disrupt the normal functioning. To know more about Formsets, Visit Official Documentation for Formsets.