django learn the basics - it.iitb.ac.in · advance concepts django rest api built in features orm...

Advance Concepts Django Rest API

DjangoLearn the Basics

Abhijit Bonik

Indian Institute of Technology Bombay

May 16, 2018


Built in features

ORM

Built in Authentication System

Template engine

Form processing

Web server for development and testing

Caching

Middleware system

An admin interface

It solves many common problems associated with Webdevelopment, such as security features, database access,sessions, template processing, URL routing,internationalization etc.


MVT Framework

Model (ORM, Database)

View (functions, classes)

Template (HTML)


Execution Flow

Figure: Execution Flow


Creating a Django project

Command - django-admin startproject Summer Internship

Directory Structure

Summer_Internship/

manage.py

Summer_Internship/

__init__.py

settings.py

urls.py

wsgi.py


Creating a module or app

Command - python3 manage.py startapp interns

Directory Structure

Summer_Internship/

manage.py

Summer_Internship/

interns/

__init__.py

admin.py

apps.py

migrations/

__init__.py

models.py

tests.py

views.py


Models

You will define all your models in models.py file for the respectivemodule.

class Interns(models.Model):

name = models.CharField(max_length=100)

address = models.TextField()

created_at = models.DateTimeField(auto_now_add=True)

institute = models.CharField(max_length=100)

Note: Every class you define in models.py file will create a table inthe database.


Views

Views are nothing but functions defined in view.py file of yourmodule.

from .models import Interns

def all_intern_details(request):

interns=Interns.objects.all()

return render(request,’interns.html’,{’interns’:interns})

Note: Each view function accepts an http request , does allprocessing, make a call to the database(models) if needed andgives a http response.


URLs

The urls are defined in the variable ’urlpatterns’

from interns import views

urlpatterns = [

url(r’^interns_details/$’, views.all_interns_details,

name = ’interns_details’),

]

Django search for all urls you enter in the browser in this variable.


Template

The template file will display the value of variables or data it hasreceived from the view function. Following is a interns.html file -

{% extends ’base.html’ %}

{% for intern in interns %}

{{ intern.name }}

{{intern.address}}

{{intern.institute}}

{% endfor %}


Get info of a single intern


def intern_profile(request, pk):

intern=Interns.objects.get(pk=pk)

return render(request, ’intern_profile.html’,

{‘intern’:intern})


URLs

The urls are defined in the variable ’urlpatterns’

from interns import views

urlpatterns = [

url(r’^interns_details/$’, views.all_interns_details,

name = ’interns_details’),

url(r’^intern_profile/(?P<pk>\d*)/$’,

views.intern_profile, name = ‘intern_profile’),

]

Django search for all urls you enter in the browser in this variable.


Display Intern details

{% extends ’base.html’ %}

<a href="{% url ‘intern_profile’ intern.pk %}">

{{ intern.name }} </a>

<p> {{intern.address}} </p>

<p> {{intern.institute}} </p>


Handling Forms in Django

Three way of creating forms in Django.

Using html tags

Using Django Form API

Using Django Model Form API


Using HTML forms- create intern.html

Create an intern details form–

<form method="post">

{% csrf_token %}

<label for="id_name">Name</label>

<input type="text" class="form-control" id="id_subject" name="name">

<label for="id_address">Address</label>

<textarea class="form-control" id="id_address" name="address" rows="5">

</textarea>

<label for="id_name">Institute</label>

<input type="text" class="form-control" id="id_institute"

name="institute">

<button type="submit" class="btn btn-success">Post</button>

</form>


Function for creating an intern

from .models import Intern

def create_intern(request):

if request.method == ’POST’:

name=request.POST[’name’]

address = request.POST[’address’]

institute = request.POST[‘institute’]

intern = Intern.objects.create(

name=name,

address=address,

institute=institute

)

return redirect(’intern_profile’, pk=intern.pk)

else:

return render(request, ‘create_intern.html’)


Forms API

Django two types of built in forms:

forms.Form

forms.ModelForm


Using form.Form Api - forms.py

from django import forms

class NewInternForm(forms.Form):

name = forms.CharField(label=’name’, max_length=100)

address = forms.CharField(label=’address’,

widget=forms.Textarea())

institute = forms.CharField(label=’institute’)


Validate with form api

from .models import Intern, Institute

from .forms import NewInternForm

def create_intern(request):


form = NewInternForm(request.POST)

if form.is_valid():

name=form.cleaned_data.get(’name’),

address = form.cleaned_data.get(’address’),

institute = form.cleaned_data.get(’institute’),

intern = Intern.objects.create(

name=name,

address=address,

institute=institute

)

return redirect(’intern_profile’, pk=intern.pk)

else:

form = NewTopicForm()

return render(request, ’create_intern.html’, {form’: form})


Display form using Form Apis

{% if user.is_authenticated %}

<form method="post">

{% csrf_token %}

{{ form.as_p }}

<button type="submit" class="btn btn-success">Post</button>

</form>

{% endif %}

The form have three rendering options: form.as table,form.as ul, and form.as p


ModelForm API


class NewInternForm(forms.ModelForm):

class Meta:

model = Interns

fields = [’name’, ’address’, ‘institute’]


View function



if form.is_valid():

intern = form.save()

return redirect("intern_profile", pk=intern.pk)

else:

form = NewInternForm()

return render(request, ’create_intern.html’, {’form’: form})


Advance Concepts


Class based views

It extends the View class.

The requests are handled inside class methods named afterthe HTTP methods- get, post, put, head, etc

So no conditional check is required

Two types -

1 Class-Based Views (CBV)2 Generic Class-Based Views (GCBV)


Create interns using- Class based views

from django.views.generic import View


class CreateInternView(View):

def post(self, request):


if form.is_valid():

intern = form.save()

return redirect(’intern_profile’, intern.pk)


def get(self, request):

form = NewInternForm()



Add more class methods

def render(self, request):

return render(request, ’create_intern.html’,

{’form’: self.form})

def post(self, request):

self.form = NewInternForm(request.POST)

if self.form.is_valid():

intern = self.form.save()

return redirect(’intern_profile’, intern.pk)

return self.render(request)

def get(self, request):

self.form = NewInternForm()

return self.render(request)


Urls for class based views

urlpatterns = [

url(r’^create_interns/$’, views.CreateInternView.as_view(),

name=’create_intern’),

]


Generic Class based Views (GCBV)

They can speed up development. Following are some mostly usedGCBV

CreateView,

DetailView

DeleteView

FormView

UpdateView

ListView.


Generic Class based views - List View

from django.views.generic import ListView


class BoardListView(ListView):

model = Interns

context_object_name = interns

template_name = interns.html’


CreateView

from django.views.generic import ListView



class CreateInternView(CreateView):

model = Interns

form_class = NewInternForm

success_url = reverse_lazy(’get_intern_details’,

kwargs={’pk’: self.object.id})

template_name = ‘create_interns.html’


DetailView

class InternProfileView(DetailView):

model = Intern

template_name = "intern_profile.html"

context_object_name = "intern"

This class will fetch the primary key from the url and return anobject of a single intern matching the key


Django Rest API


Rest API

Any application that can understand internet’s HypertextTransfer Protocol (HTTP) can communicate with each other.

REST is also a language-independent architectural style.

RESTful web services can be written using any language -Python, Java, .NET, etc.

We will use Django Rest Framework, a module of Django toimplement Rest APIs.


Django Rest Framework

It has a Web browsable API

Built in authentication scheme such as TokenAuthentication,BasicAuthentication, Sessionbased

Serialization that supports both ORM and non-ORM datasources.


Serializers

Serializers allow complex data such as querysets and modelinstances to be converted to native Python data types thatcan then be easily rendered into JSON, XML or other content types.

from rest_framework import serializers


class UserSerializer(serializers.HyperlinkedModelSerializer):

class Meta:

model = Interns

fields = (’pk’, ’name’, ’address’, ’institute’)


Class based Viewsets

from rest_framework import viewsets

from tutorial.quickstart.serializers import InternSerializer


class InternViewSet(viewsets.ModelViewSet):

queryset = Interns.objects.all().order_by(’-name’)

serializer_class = InternSerializer

Urls – Link your viewsets to url

urlpatterns = [

url(r’^api/internapi/$’, views.InternViewSet.as_view(), name=’intern_api’),

]


APIs using Django function based views

def intern_api(request):

if request.method == ’GET’:

interns = Interns.objects.all()

serializer = InternSerializer(interns, many=True)

return JsonResponse(serializer.data, safe=False)

elif request.method == ’POST’:

data = JSONParser().parse(request)

serializer = InternSerializer(data=data)

if serializer.is_valid():

serializer.save()

return JsonResponse(serializer.data, status=201)

return JsonResponse(serializer.errors, status=400)


Using Rest Framework ‘api view’ wrappers

@api_view([’GET’, ’POST’])

def intern_api(request):

if request.method == ’GET’:

interns = Interns.objects.all()

serializer = InternSerializer(interns, many=True)

return Response(serializer.data)

elif request.method == ’POST’:

serializer = InternSerializer(data=request.data)

if serializer.is_valid():

serializer.save()

return Response(serializer.data,

status=status.HTTP_201_CREATED)

return Response(serializer.errors,

status=status.HTTP_400_BAD_REQUEST)


Where we are now

What are models, views, templates, urls.

What are Form APIs

What is Class Based and Generic Class Based Views

What is Rest APIs

How to create a Rest API Using DRF

What are Serializers and Viewsets


For installation and other details refer to

https://github.com/fresearchgroup/Collaboration-System

https://fresearchgroup.github.io/docs-collaboration-system/

https://github.com/abhisgithub/django-nginx-installation-script

https://github.com/fresearchgroup/Collaboration-System

https://fresearchgroup.github.io/docs-collaboration-system/




For installation and other details refer to

Thank You!

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