Comparison of Traditional Django Views to Decorated Views for APIs

decorated_view.py

from django.views.generic import View
from django.shortcuts import get_object_or_404
from .decorators import json
from .models import RoomModel
from django.http import HttpResponse


class RoomView(View):
    """Room view class that implements the primary HTTP verbs (POST, GET, PUT, DELETE).

    All verb implementations expect to receive and return dictionary objects.  All serialization/deserialization
    is handled outside of the view itself.
    """

    @json
    def post(self, json_data, *args, **kwargs):
        """ POST verb handler (database create).  Only supports single item creation at this time.
        :param json_data: Model attributes to use in the creation of a new database entry.
        :return: Public representation of the created model.  This may not include all model fields, depending
                on how the model defines its to_data() member.
        """
        room = RoomModel(**json_data)

        try:
            room.save()
        except django.db.IntegrityError as ex:
            # Foreign or unique key error
            if "violates not-null" in str(ex):
                return HttpResponse(str(ex), status=400)
            else:
                return HttpResponse(str(ex), status=409)

        return room.to_data()

    @json
    def get(self, json_data, item_id=None, *args, **kwargs):
        """ GET verb handler (database read)
        :param json_data: Not used.
        :param item_id: (optional) Unique ID of the object to retrieve.  If not specified, all objects will be returned.
        :return: Public representation of the requested object (if item_id specified) or a dictionary containing a
                single key referencing a list of public representations of all available objects in this collection.
        """
        if item_id:
            return get_object_or_404(RoomModel, id=item_id).to_data()
        else:
            return {
                "rooms": [item_obj.to_data() for item_obj in RoomModel.objects.all()]
            }

    @json
    def put(self, json_data, item_id, *args, **kwargs):
        """ PUT verb handler (database update).  Only supports single item updates at this time.
        :param json_data: Dictionary of key/value pairs that should be updated on the specified object
        :param item_id: Unique ID of the object to update.
        :return: Public representation of the updated object
        """
        existing_item = get_object_or_404(RoomModel, id=item_id)
        
        for key, value in json_data.items():
            setattr(existing_item, key, value)

        try:
            existing_item.save()
        except django.db.IntegrityError as ex:
            # Foreign or unique key error
            if "violates not-null" in str(ex):
                return HttpResponse(str(ex), status=400)
            else:
                return HttpResponse(str(ex), status=409)

        return existing_item.to_data()

    @json
    def delete(self, json_data, item_id, *args, **kwargs):
        """ DELETE verb handler (database delete).  Only supports single item deletions at this time.
        :param json_data: Not used.
        :param item_id: Unique ID of the object to delete.
        :return: Status 204 on success, error message on failure
        """
        existing_item = get_object_or_404(RoomModel, id=item_id)
        
        try:
            existing_item.delete()
            
        except django.db.Error as ex:
            # General database error
            return HttpResponse(str(ex), status=400)

        except AssertionError as ex:
            # Django error such as "object can't be deleted because its id attribute is set to None"
            return HttpResponse(str(ex), status=400)

        return existing_item.to_data()

decorators.py

from django.http import JsonResponse, HttpResponse
from json import loads


def json(view_func):
    def wrapper(self, request, *args, **kwargs):
        # Deserialize the request body into a native dictionary
        if request.method == "GET":
            json_data = {k: v for k, v in request.GET.items()}
        elif request.body:
            json_data = loads(request.body.decode('utf-8'))
        else:
            json_data = {}

        # Call the view handler
        response = view_func(self, json_data, *args, **kwargs)

        # Translate the return into a JsonResponse if necessary.  This allows us to return native Python
        # data structures without having to remember to jsonify it.
        if isinstance(response, HttpResponse):
            # Most likely an error response.  Just pass it through
            return response
        else:
            # Return the appropriate HTTP status
            if request.method == "POST":
                status = 201  # CREATED
            elif request.method == "DELETE":
                status = 204  # NO CONTENT
            else:
                status = 200  # OK

            # Serialize
            return JsonResponse(response, status=status)

    return wrapper

models.py

from django.db import models
from django.forms import model_to_dict
import django.db
from django.http import HttpResponse
from datetime import datetime


class Room(models.Model):
    """ A chat room. """
    name = models.CharField("room name", max_length=100, unique=True, default=None)

    def to_data(self):
        """ Iterate over all attributes and return a native Python dictionary containing all attributes. """
        data = {}

        # Iterate over each of our fields and return a dictionary that contains only whitelisted fields.
        for attr_name, attr_val in model_to_dict(self).items():
            data[attr_name] = attr_val

        return data

traditional_view.py

from django.views.generic import View
from django.shortcuts import get_object_or_404
from .models import RoomModel
from json import loads
from django.http import JsonResponse, HttpResponse


class RoomView(View):
    """Room view class that implements the primary HTTP verbs (POST, GET, PUT, DELETE).

    All verb implementations expect to receive and return dictionary objects.  All serialization/deserialization
    is handled outside of the view itself.
    """

    def post(self, request, *args, **kwargs):
        """ POST verb handler (database create).  Only supports single item creation at this time.
        :param json_data: Model attributes to use in the creation of a new database entry.
        :return: Public representation of the created model.  This may not include all model fields, depending
                on how the model defines its to_data() member.
        """
        json_data = loads(request.body.decode('utf-8'))
        
        room = RoomModel(**json_data)

        try:
            room.save()
        except django.db.IntegrityError as ex:
            # Foreign or unique key error
            if "violates not-null" in str(ex):
                return HttpResponse(str(ex), status=400)
            else:
                return HttpResponse(str(ex), status=409)

        return JsonResponse(room.to_data())

    def get(self, request, item_id=None, *args, **kwargs):
        """ GET verb handler (database read)
        :param json_data: Not used.
        :param item_id: (optional) Unique ID of the object to retrieve.  If not specified, all objects will be returned.
        :return: Public representation of the requested object (if item_id specified) or a dictionary containing a
                single key referencing a list of public representations of all available objects in this collection.
        """
        if item_id:
            return JsonResponse(get_object_or_404(RoomModel, id=item_id).to_data())
        else:
            return JsonResponse({
                "rooms": [item_obj.to_data() for item_obj in RoomModel.objects.all()]
            })

    def put(self, request, item_id, *args, **kwargs):
        """ PUT verb handler (database update).  Only supports single item updates at this time.
        :param json_data: Dictionary of key/value pairs that should be updated on the specified object
        :param item_id: Unique ID of the object to update.
        :return: Public representation of the updated object
        """
        existing_item = get_object_or_404(RoomModel, id=item_id)
        
        json_data = loads(request.body.decode('utf-8'))
        
        for key, value in json_data.items():
            setattr(existing_item, key, value)

        try:
            existing_item.save()
        except django.db.IntegrityError as ex:
            # Foreign or unique key error
            if "violates not-null" in str(ex):
                return HttpResponse(str(ex), status=400)
            else:
                return HttpResponse(str(ex), status=409)

        return JsonResponse(existing_item.to_data())

    def delete(self, json_data, item_id, *args, **kwargs):
        """ DELETE verb handler (database delete).  Only supports single item deletions at this time.
        :param json_data: Not used.
        :param item_id: Unique ID of the object to delete.
        :return: Status 204 on success, error message on failure
        """
        existing_item = get_object_or_404(RoomModel, id=item_id)
        
        try:
            existing_item.delete()
            
        except django.db.Error as ex:
            # General database error
            return HttpResponse(str(ex), status=400)

        except AssertionError as ex:
            # Django error such as "object can't be deleted because its id attribute is set to None"
            return HttpResponse(str(ex), status=400)

        return JsonResponse(existing_item.to_data())