DetailView – 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 provide an alternative way to implement views as Python objects instead of functions. 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.
Class based views are simpler and efficient to manage than function-based views. A function based view with tons of lines of code can be converted into a class based views with few lines only. This is where Object Oriented Programming comes into impact.
Django DetailView – Class Based Views
Illustration of How to create and use Detail view using an Example. Consider a project named w3wiki having an app named Beginner.
Refer to the following articles to check how to create a project and 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 Beginner/models.py,
Python3
# import the standard Django Model# from built-in libraryfrom django.db import models # declare a new model with a name "BeginnerModel"class BeginnerModel(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 let’s create some instances of this model using shell, run form bash,
Python manage.py shell
Enter following commands
>>> from Beginner.models import BeginnerModel
>>> BeginnerModel.objects.create(
title="title1",
description="description1").save()
>>> BeginnerModel.objects.create(
title="title2",
description="description2").save()
>>> BeginnerModel.objects.create(
title="title2",
description="description2").save()
Now we have everything ready for back end. Verify that instances have been created from http://localhost:8000/admin/Beginner/Beginnermodel/ 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 Beginner/templates/Beginner/Beginnermodel_detail.html. Let’s create our class based view. In Beginner/views.py,
Python3
from django.views.generic.detail import DetailViewfrom .models import BeginnerModelclass BeginnerDetailView(DetailView): # specify the model to use model = BeginnerModel |
Now create a url path to map the view. In Beginner/urls.py,
Python3
from django.urls import path# importing views from views..pyfrom .views import BeginnerDetailViewurlpatterns = [ # <pk> is identification for id field, # slug can also be used path('<pk>/', BeginnerDetailView.as_view()),] |
Create a template in templates/Beginner/Beginnermodel_detail.html,
html
<h1>{{ object.title }}</h1><p>{{ object.description }}</p> |
Let’s check what is there on http://localhost:8000/1/
Manipulate Context Data in DetailView
By default DetailView will only display fields of a table. If one wants to modify this context data before sending it to template or add some extra field, context data can be overridden. In Beginner/views.py,
Python3
from django.views.generic.detail import DetailViewfrom .models import BeginnerModelclass BeginnerDetailView(DetailView): # specify the model to use model = BeginnerModel # override context data def get_context_data(self, *args, **kwargs): context = super(BeginnerDetailView, self).get_context_data(*args, **kwargs) # add extra field context["category"] = "MISC" return context |
In Beginner/templates/Beginnermodel_detail.html,
html
<h1>{{ object.title }}</h1><p>{{ object.description }}</p><p>{{ category }}</p> |
Now check, if the category is added.