Views in Python

A view function, or “view” for short, is simply a Python function that takes a web request and returns a web response. This response can be the HTML contents of a Web page, or a redirect, or a 404 error, or an XML document, or an image, etc. Example: You use view to create web pages, note that you need to associate a view to a URL to see it as a web page.

In Django, views have to be created in the app views.py file.

Simple View

We will create a simple view in myapp to say "welcome to my app!"

See the following view −

1)

from django.http import HttpResponse

def hello(request):
   text = """<h1>welcome to my app !</h1>"""
   return HttpResponse(text)

In this view, we use HttpResponse to render the HTML (as you have probably noticed we have the HTML hard coded in the view). To see this view as a page we just need to map it to a URL (this will be discussed in an upcoming chapter).

We used HttpResponse to render the HTML in the view before. This is not the best way to render pages. Django supports the MVT pattern so to make the precedent view, Django - MVT like, we will need −

2)

A template: myapp/templates/hello.html

And now our view will look like −

from django.shortcuts import render

def hello(request):
   return render(request, "myapp/template/hello.html", {})

Views can also accept parameters −

3)

from django.http import HttpResponse

def hello(request, number):
   text = "<h1>welcome to my app number %s!</h1>"% number
   return HttpResponse(text)

When linked to a URL, the page will display the number passed as a parameter. Note that the parameters will be passed via the URL (discussed in the next chapter).

Cd D:\django\myproject\myapp

Create vi views.py

from django.shortcuts import render

# Create your views here.
from django.http import HttpResponse

def hello(request):
text = """<h1>welcome to my app !</h1>"""
return HttpResponse(text)

def index(request):
text = """<h1>welcome to my app !</h1>"""
return HttpResponse(text)

###################################################################################

1. Add the following entries in myproject/urls.py

from django.contrib import admin
from django.urls import path,re_path,include

from . import views

urlpatterns = [
path('admin/', admin.site.urls),
path('hello/',views.hello,name='hello'),
re_path('display(\d+)/',views.display,name='id'),

path('myapp/',include("myapp.urls")),
]

2. create views.py in myproject/myproject /views.py

from django.shortcuts import render
from django.http import HttpResponse

# Create your views here.
#Python Functions
def hello(request):
text="""<h1> Hello World </h1>"""
return HttpResponse(text)

def display(request,id):
text="Algorithm Class, Hyderabad, Batch:48 %s"%id
return HttpResponse(text)

Hierarchical  URL

Cd D:\django\myproject\myapp

1. Create vi views.py

######NEW########

from django.shortcuts import render
from django.http import HttpResponse

# Create your views here.
#Python Functions
def hello_myapp(request):
text="""<h1> Hello World Myapp</h1>"""
return HttpResponse(text)

def hello_myapp2(request):
text="""<h1> Hello World Myapp2</h1>"""
return HttpResponse(text)

2. Create myapp/urls.py

from django.contrib import admin
from django.urls import path,re_path,include

from . import views

urlpatterns = [
path('', views.hello_myapp,name='hello_myapp' ),
path('hi/', views.hello_myapp2,name='hello_myapp2' ),

]

######NEW########

from django.shortcuts import render

# Create your views here.

from django.http import HttpResponse

#Using HttpResponse and without  using .html file

def hello(request):
text="""<h1> Welcome to my app </h1>"""
return HttpResponse(text)

#Using render using .html file

D:\lab\batch31\myproject\myapp\templates\hello.html

def hello(request):
return render(request, "hello.html", {})

# Accepting Arguments in views
def hello2(request,id):
text = "Displaying article Number : %s"%id
return HttpResponse(text)

# Passing arguments to html
D:\lab\batch31\myproject\myapp\templates\hello2.html

def hello3(request,id):
return render(request, "hello2.html", {"today" : id})

vi myproject/urls.py and add the following lines

from django.contrib import admin
from django.urls import path,include
from . import views

urlpatterns = [
path('admin/', admin.site.urls),
path('display/', views.hello,name='hello'),
path('myapp/', include('myapp.urls')),
]

** Create new file urls.py in myapp

vi myproject/myapp/urls.py and add the following lines

Note: we have to use re_path with regular expressions

from django.contrib import admin
from django.urls import path,re_path
from . import views

urlpatterns = [
#'myapp.views',
#path('admin/', admin.site.urls),
path('', views.hello,name='hello1'),
re_path('display(\d+)', views.hello2,name='id'), 
re_path('temp(\d+)', views.hello3,name='id'),
]

Create folder templates

cd D:\lab\batch31\myproject\myapp\templates

vi hello2.html

<html>

<body>
Hello World!!!<p>Today is {{today}}</p>
</body>

</html>

###################################################################################

Python manage.py makemigrations
Python manage.py migrate

Python manage.py shell

>>> from geeks.models import GeeksModel
>>> GeeksModel.objects.create(
                       title="title1",
                       description="description1").save()
>>> GeeksModel.objects.create(
                       title="title2",
                       description="description2").save()
>>> GeeksModel.objects.create(
                       title="title2",
                       description="description2").save()

Django CRUD (Create, Retrieve, Update, Delete) Function Based Views

Python manage.py makemigrations
Python manage.py migrate

Python manage.py makemigrations
Python manage.py migrate

Class based views

myapp/urls.py

path('about/', views.MyView.as_view()), # Class based
path('create/', views.RtiCreate.as_view()),
path('list/', views.RtiList.as_view()),
path('<pk>/detail', views.RtiDetailView.as_view()),
path('<pk>/update',views.RtiUpdateView.as_view()),
path('<id>/delete', views.RtiDeleteView,name="id" ),
path('form', views.RtiFormView.as_view()),

myapp/views.py

# For the above code equivalent class based code

from django.views import View

class MyView(View): # Class based
def get(self, request):
# <view logic>
return HttpResponse('result')

from django.views.generic.edit import CreateView
from .models import RTI

class RtiCreate(CreateView): # Create view

# specify the model for create view
model =RTI

# specify the fields to be displayed

fields = ['rti_no', 'rti_label','rti_lrg','rti_dif','rti_symptom','rti_status']

success_url = "/rti/about"

from django.views.generic.list import ListView
from .models import RTI
class RtiList(ListView):
# specify the model for list view
model = RTI

from django.views.generic.detail import DetailView
from .models import RTI

class RtiDetailView(DetailView):
# specify the model to use
model = RTI

from django.views.generic.edit import UpdateView

from .models import RTI

class RtiUpdateView(UpdateView):

# specify the model for create view
model =RTI

# specify the fields to be displayed

fields = ['rti_no', 'rti_label','rti_lrg','rti_dif','rti_symptom']

success_url = "/rti/about"

from django.views.generic.edit import FormView
from .forms import RtiForm

class RtiFormView(FormView):

# specify the model for create view
model =RtiForm

# sepcify name of template
template_name = "rti_form.html"

success_url = "/rti/about"

myapp/templates/myapp

cat rti_detail.py

<head>

<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">

<!-- Bootstrap CSS -->
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-wEmeIV1mKuiNpC+IOBjI7aAzPcEZeedi5yW5f2yOq55WWLwNGmvvx4Um1vskeMj0" crossorigin="anonymous">
</head>

<body>

<ul>

<table class="table">
<thead>

<tr>
<th scope="col">RTI#</th>
<th scope="col">DIF</th>
<th scope="col">LRG</th>
<th scope="col">SYMPTOM</th>
</tr>
</thead>

<tbody>
<!-- Iterate over object_list -->

<!-- Display Objects -->
<tr>

<td>{{ object.rti_no }}</td>
<td>{{ object.rti_dif }}</td>
<td>{{ object.rti_lrg }}</td>
<td>{{ object.rti_symptom }}</td>
</tr>

</tbody>
</table>

<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0/dist/js/bootstrap.bundle.min.js" integrity="sha384-p34f1UUtsS3wqzfto5wAAmdvj+osOnFyQFpp4Ua3gs/ZVWx6oOypYoCJhGGScy+8" crossorigin="anonymous"></script>
</body>

myapp/template/myapp/rti_form.html

<head>

<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">

<!-- Bootstrap CSS -->
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-wEmeIV1mKuiNpC+IOBjI7aAzPcEZeedi5yW5f2yOq55WWLwNGmvvx4Um1vskeMj0" crossorigin="anonymous">
</head>

<body>

<form method="POST" enctype="multipart/form-data">

<!-- Security token -->
{% csrf_token %}

<!-- Using the formset -->
{{ form.as_p }}

<input type="submit" value="Submit">
</form>

<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0/dist/js/bootstrap.bundle.min.js" integrity="sha384-p34f1UUtsS3wqzfto5wAAmdvj+osOnFyQFpp4Ua3gs/ZVWx6oOypYoCJhGGScy+8" crossorigin="anonymous"></script>

</body>

myapp/template/myapp/rti_list

<head>

<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">

<!-- Bootstrap CSS -->
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-wEmeIV1mKuiNpC+IOBjI7aAzPcEZeedi5yW5f2yOq55WWLwNGmvvx4Um1vskeMj0" crossorigin="anonymous">
</head>

<body>

<ul>

<table class="table">
<thead>

<tr>
<th scope="col">RTI#</th>
<th scope="col">DIF</th>
<th scope="col">LRG</th>
<th scope="col">SYMPTOM</th>
</tr>
</thead>

<tbody>
<!-- Iterate over object_list -->
{% for object in object_list %}
<!-- Display Objects -->
<tr>

<td>{{ object.rti_no }}</td>
<td>{{ object.rti_dif }}</td>
<td>{{ object.rti_lrg }}</td>
<td>{{ object.rti_symptom }}</td>
</tr>
{% endfor %}
</tbody>
</table>

<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0/dist/js/bootstrap.bundle.min.js" integrity="sha384-p34f1UUtsS3wqzfto5wAAmdvj+osOnFyQFpp4Ua3gs/ZVWx6oOypYoCJhGGScy+8" crossorigin="anonymous"></script>
</body>