1. create virtual enviroments virtualenv env
2. active virtual enviroments source /env/bin/activate
3. installing dependencies pip3 install django plus pip3 install djangorestframework
4. create a django project django-admin startproject <project-name>

5. install the framework in the django-project setting file

...
rest_framework

6. make a app module ./manage.py startapp <app-name>
7. install the app module in setting.py
8. all done! now we can import rest_framework

the serializer is a class which return a json whenever the coresponding api is called. ant the serializer to the reverse too! it get an json and return it to a django.models.object.

there is some serializer which doing various things.

1. HyperLinkedModelSerializer

   1.1 this will creat a link for each object from it uniq_id.

2. ModelSerializer

   2.1 will just serialize/deserialize the model.

to use one of thease Serializer, we should import it and then inherit one of theme as the case setiation.

the Meta class will tell the Serializer to user which model instance and which one of it`s fields.

Note that we can use __all__ for all the fields

from rest_framework import serializer
from .models import User


class UserSerializer(serializer.HyperLinkedSerializer):
    class Meta:
        model = User
        fields = [
            'username',
            'first_name',
            'last_name',
        ]

• an important thing in serializer is validator

with validator we can validate the data which User passed to the server. for example think of we need to check the user hase eough credit to by a product or not.

class DemandSerializer(Serializer.ModelSerializer):
    class Meta:
        model = Demand
        fields = [
            'customer',
            'producer',
            'product',
            'replica'
        ]

    def validate(self, data):
        """
        check the credit of the user,
        check the entity of the product
        """
        
        def validated_data['product'].entity >= validated_data['replica']:
            if validated_data['customer'].amount >= (validated_data['product'].price * validated_data['replica']):
                reise serializer.ValidateErroe('buy credit')
            reise serializer.ValidateError('there is not enough of this product')
        return data

• another important thing in seializer is actions

actions are used to do something! in our example we can reduce the cedit amount of the user and reduce the entity of the product

actions are limited to: list, create, retrive, update, destroy.

# we do create in this example
# when a user requested, and the price and user amount are enough
# and the entity and the replica of the product are anough, this function will run
class DemandSerializer(Serializer.ModelSerializer):
    ...

    def create(self, validated_data):
        user = Customer.objects.get(pk=validated_data['consumer'].pk)
        product_price = validated_data['product'].price
        user.account_amount = user.account_amount - product_price * int(validated_data['replica'])
        user.save()
        return validated_data

ViewSet are a set of view which represent the data, handel the requests. in oder to use viewSet we should use of the views, in my case i use Viewsets.ModelViewSet which can do all the stuff, like list, create, update, etc and or 'get','post', 'put', 'etc' if you need to edit the behavior, you can overrider the each of this actions.

in this case i overide the create to reduce the customer credit amount

from .serializer import DemandSerializer
from .model import Customer
class DemandSerializer(ViewSets.ModelViewset):
    queryset = Demand.object.all()
    serializer_class = DemandSerializer # we use this for all other functions

    def create(self, request):
        serializer_class = DemandSerialzer
        if serializer_class.is_valid():
            final_price = serializer_class.validated_data['product'].price * serializer_class.validate_data['replica']
            user = validate_date['consumer'].id
            user = Customer.object.get(pk=int(user))
            user.account_amout = user.account_amount - final_price
            user.accont_amount.save()

...

• instalation while your venv is activate run this commands

1. pip3 install djangorestframework_simplejwt
2. import the jwt from rest_framework_simplejwt.views import TokenObtainPairView, TokenRefreshView in urls.py

3. now set this plugin in the installed app

INSTALLED_APPS = [
    'rest_framework_simplejwt',
]


# setting and config for jwt is 

SIMPLE_JWT = {
# setting of jwt are config here with dict
}

1. config the jwt urls

urlpatterns = [
    path('api/token/verify/', TokenVerifyView.as_view(), name='token_verify'),
]

5. all done! just curl the site with username and password of one user to retrive two differnt token. 5.1 firest one is used to access the data. 5.2 is used to revoke the token

   $ curl \

-X POST
-H "Content-Type: application/json"
-d '{"username": "admin", "password": "12345678"}'
http://localhost:8000/api/token/

"access":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX3BrIjoxLCJ0b2tlbl90eXBlIjoiYWNjZXNzIiwiY29sZF9zdHVmZiI6IuKYgyIsImV4cCI6MTIzNDU2LCJqdGkiOiJmZDJmOWQ1ZTFhN2M0MmU4OTQ5MzVlMzYyYmNhOGJjYSJ9.NHlztMGER7UADHZJlxNG0WSi22a2KaYSfd1S-AuT7lU", "refresh":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX3BrIjoxLCJ0b2tlbl90eXBlIjoicmVmcmVzaCIsImNvbGRfc3R1ZmYiOiLimIMiLCJleHAiOjIzNDU2NywianRpIjoiZGUxMmY0ZTY3MDY4NDI3ODg5ZjE1YWMyNzcwZGEwNTEifQ.aEoAYkSJjoWH1boshQAaTkf8G3yn0kapko6HFRt7Rh4" }

6. revoke the token

to revoke the token just curl the refresh address with the last token and it will give you another access token.

```python
curl \
-H "Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX3BrIjoxLCJ0b2tlbl90eXBlIjoiYWNjZXNzIiwiY29sZF9zdHVmZiI6IuKYgyIsImV4cCI6MTIzNDU2LCJqdGkiOiJmZDJmOWQ1ZTFhN2M0MmU4OTQ5MzVlMzYyYmNhOGJjYSJ9.NHlztMGER7UADHZJlxNG0WSi22a2KaYSfd1S-AuT7lU" \
http://localhost:8000/api/some-protected-view/