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 {}

Doesnot seems to be working. The images fields which has manytomany association with Image model and has been assign a serializer of Image serializer. But , when we request it from postman the field it throws an error message of images field is required even the data is provided.

Doesnot seems to be working. The images fields which has manytomany association with Image model and has been assign a serializer of Image serializer. But , when we request it from postman the field it throws an error message of images field is required even the data is provided.

same issue