Class Based Generic Views Django (Create, Retrieve, Update, Delete) - GeeksforGeeks

21 Sep, 2021
Django is a Python-based web framework that allows you to quickly create web applications. It has built-in admin interface which makes easy to work with it. It is often called Batteries included framework because it provides built-in facilities for every functionality. Class Based Generic Views are advanced set of Built-in views which are used for implementation of selective view strategies such as Create, Retrieve, Update, Delete. Class based views simplify the use by separating GET, POST requests for a view. They do not replace function-based views, but have certain differences and advantages when compared to function-based views:
Organization of code related to specific HTTP methods (GET, POST, etc.) can be addressed by separate methods instead of conditional branching.
Object oriented techniques such as mixins (multiple inheritance) can be used to factor code into reusable components.
This article revolves around complete implementation of Class Based Views in Django (Create, Retrieve, Update, Delete). Let’s discuss what actually CRUD means,
CreateView – create or add new entries in a table in the database. Retrieve Views – read, retrieve, search, or view existing entries as a list(ListView) or retrieve a particular entry in detail (DetailView) UpdateView – update or edit existing entries in a table in the database DeleteView – delete, deactivate, or remove existing entries in a table in the database FormView – render a form to template and handle data entered by user
Illustration of How to create and use CRUD views using an Example. Consider a project named geeksforgeeks having an app named geeks.  
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 ?
After you have a project and an app, let’s create a model of which we will be creating instances through our view. In geeks/models.py,  
Python3
# import the standard Django Model# from built-in libraryfrom django.db import models  # declare a new model with a name "GeeksModel"class GeeksModel(models.Model):     # fields of the model    title = models.CharField(max_length = 200)    description = models.TextField()     # renames the instances of the model    # with their title name    def __str__(self):        return self.title
After creating this model, we need to run two commands in order to create Database for the same. 
Python manage.py makemigrations
Python manage.py migrate
Now we will create a Django ModelForm for this model. Refer this article for more on modelform – Django ModelForm – Create form from Models. create a file forms.py in geeks folder,  
Python3
from django import formsfrom .models import GeeksModel  # creating a formclass GeeksForm(forms.ModelForm):     # create meta class    class Meta:        # specify model to be used        model = GeeksModel         # specify fields to be used        fields = [            "title",            "description",        ]
At its core, a class-based view allows you to respond to different HTTP request methods with different class instance methods, instead of with conditionally branching code inside a single view function.
So where the code to handle HTTP GET in a view function would look something like: 
Python3
from django.http import HttpResponse def my_view(request):    if request.method == 'GET':        # <view logic>        return HttpResponse('result')
In a class-based view, this would become:
Python3
from django.http import HttpResponsefrom django.views import View class MyView(View):    def get(self, request):        # <view logic>        return HttpResponse('result')
Similarly in urls.py, one needs to use as_view() method to differentiate a class based view from function based view. 
Python3
# urls.pyfrom django.urls import pathfrom myapp.views import MyView urlpatterns = [     path('about/', MyView.as_view()), ]
Create View refers to a view (logic) to create an instance of a table in the database. We have already discussed basics of Create View in Create View – Function based Views Django. Class Based Views automatically setup everything from A to Z. One just needs to specify which model to create Create View for and the fields. Then Class based CreateView will automatically try to find a template in app_name/modelname_form.html. In our case it is geeks/templates/geeks/geeksmodel_form.html. Let’s create our class based view. In geeks/views.py, 
Python3
from django.views.generic.edit import CreateViewfrom .models import GeeksModel class GeeksCreate(CreateView):     # specify the model for create view    model = GeeksModel     # specify the fields to be displayed     fields = ['title', 'description']
Now create a url path to map the view. In geeks/urls.py, 
Python3
from django.urls import path # importing views from views..pyfrom .views import GeeksCreateurlpatterns = [    path('', GeeksCreate.as_view() ),]
Create a template in templates/geeks/geeksmodel_form.html, 
HTML
<form method="POST" enctype="multipart/form-data">     <!-- Security token -->    {% csrf_token %}     <!-- Using the formset -->    {{ form.as_p }}         <input type="submit" value="Submit"></form>
Let’s check what is there on http://localhost:8000/ 
To check complete implementation of Class based CreateView, visit Createview – Class Based Views Django. 
List View refers to a view (logic) to display multiple instances of a table in the database. We have already discussed basics of List View in List View – Function based Views Django. Class Based Views automatically setup everything from A to Z. One just needs to specify which model to create ListView for, then Class based ListView will automatically try to find a template in app_name/modelname_list.html. In our case it is geeks/templates/geeks/geeksmodel_list.html. Let’s create our class based view. In geeks/views.py, 
Python3
from django.views.generic.list import ListViewfrom .models import GeeksModel class GeeksList(ListView):     # specify the model for list view    model = GeeksModel
Now create a url path to map the view. In geeks/urls.py, 
Python3
from django.urls import path # importing views from views..pyfrom .views import GeeksListurlpatterns = [    path('', GeeksList.as_view()),]
Create a template in templates/geeks/geeksmodel_list.html, 
HTML
<ul>    <!-- Iterate over object_list -->    {% for object in object_list %}    <!-- Display Objects -->    <li>{{ object.title }}</li>    <li>{{ object.description }}</li>     <hr/>    <!-- If object_list is empty  -->    {% empty %}    <li>No objects yet.</li>    {% endfor %}</ul>
Let’s check what is there on http://localhost:8000/ 
To check complete implementation of Class based ListView, visit ListView – Class Based Views Django
Detail View refers to a view (logic) to display one instances of a table in the database. We have already discussed basics of Detail View in Detail View – Function based Views Django. Class Based Views automatically setup everything from A to Z. One just needs to specify which model to create DetailView for, then Class based DetailView will automatically try to find a template in app_name/modelname_detail.html. In our case it is geeks/templates/geeks/geeksmodel_detail.html. Let’s create our class based view. In geeks/views.py, 
Python3
from django.views.generic.detail import DetailView from .models import GeeksModel class GeeksDetailView(DetailView):    # specify the model to use    model = GeeksModel
Now create a url path to map the view. In geeks/urls.py, 
Python3
from django.urls import path # importing views from views..pyfrom .views import GeeksDetailViewurlpatterns = [    # <pk> is identification for id field,    # slug can also be used    path('<pk>/', GeeksDetailView.as_view()),]
Create a template in templates/geeks/geeksmodel_detail.html, 
HTML
<h1>{{ object.title }}</h1>   <p>{{ object.description }}</p>
Let’s check what is there on http://localhost:8000/1/ 
To check complete implementation of Class based DetailView, visit DetailView – Class Based Views Django 
UpdateView refers to a view (logic) to update a particular instance of a table from the database with some extra details. It is used to update entries in the database for example, updating an article at geeksforgeeks. We have already discussed basics of Update View in Update View – Function based Views Django. Class Based Views automatically setup everything from A to Z. One just needs to specify which model to create UpdateView for, then Class based UpdateView will automatically try to find a template in app_name/modelname_form.html. In our case it is geeks/templates/geeks/geeksmodel_form.html. Let’s create our class based view. In geeks/views.py, 
Python3
# import generic UpdateViewfrom django.views.generic.edit import UpdateView # Relative import of GeeksModelfrom .models import GeeksModel class GeeksUpdateView(UpdateView):    # specify the model you want to use    model = GeeksModel     # specify the fields    fields = [        "title",        "description"    ]     # can specify success url    # url to redirect after successfully    # updating details    success_url ="/"
Now create a url path to map the view. In geeks/urls.py, 
Python3
from django.urls import path # importing views from views..pyfrom .views import GeeksUpdateViewurlpatterns = [    # <pk> is identification for id field,    # <slug> can also be used    path('<pk>/update', GeeksUpdateView.as_view()),]
Create a template in templates/geeks/geeksmodel_form.html, 
HTML
<form method="post">    {% csrf_token %}    {{ form.as_p }}    <input type="submit" value="Save"></form>
Let’s check what is there on http://localhost:8000/1/update/ 
To check complete implementation of Class based UpdateView, visit UpdateView – Class Based Views Django. 
Delete View refers to a view (logic) to delete a particular instance of a table from the database. It is used to delete entries in the database for example, deleting an article at geeksforgeeks. We have already discussed basics of Delete View in Delete View – Function based Views Django. Class Based Views automatically setup everything from A to Z. One just needs to specify which model to create DeleteView for, then Class based DeleteViewde will automatically try to find a template in app_name/modelname_confirm_delete.html. In our case it is geeks/templates/geeks/geeksmodel_confirm_delete.html. Let’s create our class based view. In geeks/views.py, 
Python3
# import generic UpdateViewfrom django.views.generic.edit import DeleteView # Relative import of GeeksModelfrom .models import GeeksModel class GeeksDeleteView(DeleteView):    # specify the model you want to use    model = GeeksModel         # can specify success url    # url to redirect after successfully    # deleting object    success_url ="/"
Now create a url path to map the view. In geeks/urls.py, 
Python3
from django.urls import path # importing views from views..pyfrom .views import GeeksDeleteViewurlpatterns = [    # <pk> is identification for id field,    # slug can also be used    path('<pk>/delete/', GeeksDeleteView.as_view()),]
Create a template in templates/geeks/geeksmodel_confirm_delete.html, 
HTML
<form method="post">{% csrf_token %}       <p>Are you sure you want to delete "{{ object }}"?</p>       <input type="submit" value="Confirm"></form>
Let’s check what is there on http://localhost:8000/1/delete 
To check complete implementation of Class based DeleteView, visit DeleteView – Class Based Views Django
FormView refers to a view (logic) to display and verify a Django Form. For example a form to register users at geeksforgeeks. Class Based Views automatically setup everything from A to Z. One just needs to specify which form to create FormView for and template_name, then Class based FormView will automatically render that form. Let’s create our class based view. In geeks/views.py,  
Python3
# import generic FormViewfrom django.views.generic.edit import FormView # Relative import of GeeksFormfrom .forms import GeeksForm class GeeksFormView(FormView):    # specify the Form you want to use    form_class = GeeksForm         # specify name of template    template_name = "geeks / geeksmodel_form.html"     # can specify success url    # url to redirect after successfully    # updating details    success_url ="/thanks/"
Create a template for this view in geeks/geeksmodel_form.html, 
HTML
<form method="post">    {% csrf_token %}    {{ form.as_p }}    <input type="submit" value="Save"></form>
Map a url to this view in geeks/urls.py, 
Python3
from django.urls import path # importing views from views..pyfrom .views import GeeksFormViewurlpatterns = [    path('', GeeksFormView.as_view()),]
Now visit http://127.0.0.1:8000/, 
To check complete implementation of Class based FormView, visit FormView – Class Based Views Django 
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