Class-Based Views (CBVs) allow developers to handle HTTP requests in a structured and reusable way. With CBVs, different HTTP methods (like GET, POST) are handled as separate methods in a class, which helps with code organization and reusability.

Advantages of CBVs

• Separation of Logic: CBVs separate different behaviors (GET, POST) into separate methods.
• Reusable Components:Common functionality can be factored out into reusable mixins or base classes.
• Built-in Generic Views: Django provides several built-in CBVs like CreateView, ListView, DetailView, etc., for common tasks.

• 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

Django Class Based Views CRUD Operations

Illustration ofHow 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 ?

Let’s now see how to implement CRUD operations using CBVs in Django.

Step 1: Define the Model

The first step is to define the model in Django. For our example, let’s create a model named GeeksModel to store the title and description of a record.

Ingeeks/models.py:

fromdjango.dbimportmodelsclassGeeksModel(models.Model):title=models.CharField(max_length=200)description=models.TextField()def__str__(self):returnself.title

Explanation:

• title:A CharField for the title of the record.
• description:A TextField for the description of the record.

Run the following commands to create and apply database migrations:

Python manage.py makemigrations
Python manage.py migrate

Step 2: Create a ModelForm

To make it easier to create and update GeeksModel instances, let’s create a ModelForm. This form automatically generates a form for the model’s fields.

Ingeeks/forms.py:

fromdjangoimportformsfrom.modelsimportGeeksModelclassGeeksForm(forms.ModelForm):classMeta:model=GeeksModelfields=["title","description",]

Explanation:

• GeeksForm: A form class that generates a form for GeeksModel with fields title and description

Step 3: Create Class-Based Views

CreateView (For Creating Entries)

The CreateView class-based view provides the functionality to create new database records. We will use it to add new GeeksModel entries.

Ingeeks/views.py:

fromdjango.views.generic.editimportCreateViewfrom.modelsimportGeeksModelclassGeeksCreate(CreateView):model=GeeksModelfields=['title','description']template_name='geeks/geeksmodel_form.html'success_url='/'

Explanation:

• model: Specifies the model that the view will work with.
• fields:Specifies the fields that will be displayed on the form.
• template_name: Points to the HTML template where the form will be rendered.
• success_url: Defines the URL to redirect to after successfully creating a new entry.

reate the corresponding templategeeks/geeksmodel_form.html:

<formmethod="POST">    {% csrf_token %}    {{ form.as_p }}<inputtype="submit"value="Submit"></form>

URL Mapping:In geeks/urls.py, map theGeeksCreate view:

fromdjango.urlsimportpathfrom.viewsimportGeeksCreateurlpatterns=[path('create/',GeeksCreate.as_view(),name='geeks_create'),]

Let's check what is there on "http://localhost:8000/" 

To check complete implementation of Class based CreateView, visitCreateview – Class Based Views Django. 

ListView (For Retrieving Multiple Entries)

The ListView class-based view is used to retrieve and display a list of records.

Ingeeks/views.py:

fromdjango.views.generic.listimportListViewfrom.modelsimportGeeksModelclassGeeksList(ListView):model=GeeksModeltemplate_name='geeks/geeksmodel_list.html'context_object_name='geeks_list'

Create the corresponding template geeks/geeksmodel_list.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>

URL Mapping:In geeks/urls.py, map theGeeksList view:

fromdjango.urlsimportpathfrom.viewsimportGeeksListurlpatterns=[path('',GeeksList.as_view(),name='geeks_list'),]

Let's check what is there on "http://localhost:8000/"

To check complete implementation of Class based ListView, visitListView – Class Based Views Django

DetailView (For Retrieving a Single Entry)

The DetailView is used to display detailed information about a single record.

Ingeeks/views.py:

fromdjango.views.generic.detailimportDetailViewfrom.modelsimportGeeksModelclassGeeksDetailView(DetailView):# specify the model to usemodel=GeeksModel

Now create a url path to map the view. In geeks/urls.py, 

fromdjango.urlsimportpath# importing views from views..pyfrom.viewsimportGeeksDetailViewurlpatterns=[# <pk> is identification for id field,# slug can also be usedpath('<pk>/',GeeksDetailView.as_view()),]

Create a template in templates/geeks/geeksmodel_detail.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, visitDetailView – Class Based Views Django 

UpdateView (For Updating Entries)

The UpdateView allows you to edit an existing record.

Ingeeks/views.py:

fromdjango.views.generic.editimportUpdateViewfrom.modelsimportGeeksModelclassGeeksUpdateView(UpdateView):model=GeeksModelfields=["title","description"]success_url="/"

Now create a url path to map the view. In geeks/urls.py, 

fromdjango.urlsimportpathfrom.viewsimportGeeksUpdateViewurlpatterns=[path('<pk>/update',GeeksUpdateView.as_view()),]

Create a template in templates/geeks/geeksmodel_form.html, 

<formmethod="post">    {% csrf_token %}    {{ form.as_p }}<inputtype="submit"value="Save"></form>

Let's check what is there on "http://localhost:8000/1/update/" 

To check complete implementation of Class based UpdateView, visitUpdateView – Class Based Views Django. 

DeleteView (For Deleting Entries)

The DeleteView allows you to delete a record from the database.

Ingeeks/views.py:

fromdjango.views.generic.editimportDeleteViewfrom.modelsimportGeeksModelclassGeeksDeleteView(DeleteView):model=GeeksModelsuccess_url="/"

Now create a url path to map the view. In geeks/urls.py, 

fromdjango.urlsimportpathfrom.viewsimportGeeksDeleteViewurlpatterns=[path('<pk>/delete/',GeeksDeleteView.as_view()),]

Create a template in templates/geeks/geeksmodel_confirm_delete.html, 

<formmethod="post">{% csrf_token %}<p>Are you sure you want to delete "{{ object }}"?</p><inputtype="submit"value="Confirm"></form>

Let's check what is there on "http://localhost:8000/1/delete"

To check complete implementation of Class based DeleteView, visitDeleteView – Class Based Views Django

FormView (For Handling Forms)

The FormView is used to display and process forms. It provides a way to handle form submissions using CBVs.

Ingeeks/views.py:

fromdjango.views.generic.editimportFormViewfrom.formsimportGeeksFormclassGeeksFormView(FormView):form_class=GeeksFormtemplate_name="geeks / geeksmodel_form.html"success_url="/thanks/"

Create a template for this view in geeks/geeksmodel_form.html, 

<formmethod="post">    {% csrf_token %}    {{ form.as_p }}<inputtype="submit"value="Save"></form>

Map a url to this view in geeks/urls.py, 

fromdjango.urlsimportpathfrom.viewsimportGeeksFormViewurlpatterns=[path('',GeeksFormView.as_view()),]

Now visit "http://127.0.0.1:8000/"

To check complete implementation of Class based FormView, visitFormView – Class Based Views Django

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