Writable Nested Serializers | Multiple Images Upload | DRF

models.py

#!/usr/bin/env python3.6.4
# coding="UTF-8"

__author__ = 'Toran Sahu <toran.sahu@yahoo.com>'
__copyright__ = 'Copyright (C) 2018 Ethereal Machines Pvt. Ltd. All rights reserved'


from django.db import models
from os import path
from utils import directory_path_with_id
from django.utils.text import slugify
from django.db.models import Lookup, Transform
from django.db.models.fields import Field, CharField


# Create your models here.

class Image(models.Model):
    # image = models.CharField(blank=True, null=True, max_length=50)
    image = models.ImageField(blank=True, null=True, upload_to=directory_path_with_id)


class Post(models.Model):
    title = models.CharField(max_length=50, unique=True)
    content = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    thumbnail = models.ImageField(blank=True, null=True, upload_to=directory_path_with_id)
    images = models.ManyToManyField(Image, related_name='posts')

    def __str__(self):
        return self.title

    def get_slugged_title(self):
        return slugify(self.title)

serializers.py

#!/usr/bin/env python3.6.4
# coding="UTF-8"

__author__ = 'Toran Sahu <toran.sahu@yahoo.com>'
__copyright__ = 'Copyright (C) 2018 Ethereal Machines Pvt. Ltd. All rights reserved'


from rest_framework import serializers
from .models import Post, Image


class ImageSerializer(serializers.ModelSerializer):

    class Meta:
        model = Image
        fields = '__all__'


class PostSerializer(serializers.ModelSerializer):
    images = ImageSerializer(many=True)

    class Meta:
        model = Post
        fields = '__all__'

    def create(self, validated_data):
        """
        Handle writable nested serializer to create a new post.

        :param validated_data: validated data, by serializer class's validate method
        :return: updated Post model instance
        """
        # TODO: Handle the case to avoid new Post instance creation if Image model data have any errors
        data = validated_data.copy()
        data.pop('images')  # deleting 'images' list as it is not going to be used

        '''
        Fetching `images` list of image files explicitly from context.
        Because using default way, value of `images` received at serializers from viewset was an empty list.
        However value of `images` in viewset were OK.
        Hence applied this workaround.   
        '''
        images_data = self.context.get('request').data.pop('images')
        try:
            post = Post.objects.create(**data)
        except TypeError:
            msg = (
                    'Got a `TypeError` when calling `Post.objects.create()`.'
            )
            raise TypeError(msg)
        try:
            for image_data in images_data:
                # Image.objects.create(post=post, **image_data)
                image, created = Image.objects.get_or_create(image=image_data)
                post.images.add(image)

            return post
        except TypeError:
            post = Post.objects.get(pk=post.id)
            post.delete()
            msg = (
                    'Got a `TypeError` when calling `Image.objects.get_or_create()`.'
            )
            raise TypeError(msg)

        return post

    def update(self, instance, validated_data):
        """
        Handle writable nested serializer to update the current post.

        :param instance: current Post model instance
        :param validated_data: validated data, by serializer class's validate method
        :return: updated Post model instance
        """
        # TODO: change the definition to make it work same as create()

        '''
        overwrite post instance fields with new data if not None, else assign the old value
        '''
        instance.title = validated_data.get('title', instance.title)
        instance.content = validated_data.get('content', instance.content)
        instance.thumbnail = validated_data.get('thumbnail', instance.thumbnail)
        # instance.updated_at = validated_data.get('updated_at', instance.updated_at)  # no need to update; auto_now;

        try:

            '''
            Fetching `images` list of image files explicitly from context.
            Because using default way, value of `images` received at serializers from viewset was an empty list.
            However value of `images` in viewset were OK.
            Hence applied this workaround.   
            '''
            images_data = self.context.get('request').data.pop('images')
        except:
            images_data = None

        if images_data is not None:
            image_instance_list = []
            for image_data in images_data:
                image, created = Image.objects.get_or_create(image=image_data)
                image_instance_list.append(image)

            instance.images.set(image_instance_list)

        instance.save()  # why? see base class code; need to save() to make auto_now work
        return instance

test_files_upload.py

import requests
import json

url = 'http://127.0.0.1:8000/api/v1/posts/'
patch_url = 'http://127.0.0.1:8000/api/v1/posts/2/'
# url = 'http://192.168.1.106:8000/api/v1/posts/'
with open('/home/toran/Desktop/FB_IMG_1475551548845.jpeg', 'rb') as f:
    files = {'thumbnail': ('fb.jpeg', f)}
    f_aws = open('/home/toran/Pictures/aws-https.png', 'rb')
    f_ami = open('/home/toran/Pictures/ami.png', 'rb')

    files = {'thumbnail': ('aws.png', f_aws)}
    multiple_files = [
        ('images', ('foo.png', f)),
        ('images', ('bar.png', f_ami)),
        ('thumbnail', ('aws.png', f_aws)),
    ]

    data = dict()
    data['title'] = '2'
    data['content'] = 'something'

    patch_data = dict()
    patch_data['content'] = 'something else'

    # res = requests.post(url, data, files=files, headers={'content_type': 'multipart/form-data'})
    # res = requests.post(url, data=data, files=multiple_files, headers={'content_type': 'multipart/form-data'})
    res = requests.patch(patch_url, data=patch_data,  files=multiple_files, headers={'content_type': 'multipart/form-data'})
    print(res.text)


# blog_url = 'http://127.0.0.1:8000/api/v1/blogs/1/'
# files = {'thumbnail': ('aws.png', open('/home/toran/Pictures/aws-https.png', 'rb'))}
# res = requests.patch(blog_url, files=files, headers={'content_type': 'multipart/form-data'})
# print(res.text)

views.py

#!/usr/bin/env python3.6.4
# coding="UTF-8"

__author__ = 'Toran Sahu <toran.sahu@yahoo.com>'
__copyright__ = 'Copyright (C) 2018 Ethereal Machines Pvt. Ltd. All rights reserved'


from rest_framework import viewsets, mixins, status
from rest_framework.settings import api_settings
from .models import Image, Post
from .serializers import PostSerializer, ImageSerializer
from rest_framework.parsers import MultiPartParser, FormParser
from backend.permissions import IsAuthenticatedOrReadOnly
from rest_framework.response import Response


# Create your views here.

class PostViewSet(viewsets.ModelViewSet):
    """
    Post ModelViewSet.
    """
    queryset = Post.objects.all()
    serializer_class = PostSerializer
    parser_classes = (MultiPartParser, FormParser)
    # permission_classes = (IsAuthenticatedOrReadOnly,)

    def create(self, request, *args, **kwargs):
        print(request.data)
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

    def perform_create(self, serializer):
        serializer.save()

    def get_success_headers(self, data):
        try:
            return {'Location': str(data[api_settings.URL_FIELD_NAME])}
        except (TypeError, KeyError):
            return {}