7👍
Possible duplicate — Django REST: Uploading and serializing multiple images.
From the DRF Writable Nested Serializer doc,
By default nested serializers are read-only. If you want to support write-operations to a nested serializer field you’ll need to create
create()and/orupdate()methods in order to explicitly specify how the child relationships should be saved.
From this, it’s clear that the child serializer (BinaryFileSerializer) won’t call its own create() method unless explicitly called.
The aim of your HTTP POST request is to create new Submission instance (and BinaryFile instance). The creation process undergoes in the create() method of the SubmissionCreateSerializer serializer, which is you’d overridden. So, it will act/execute as per your code.
UPDATE-1
Things to remember
1. AFAIK, we can’t send nested multipart/form-data
2. Here I’m only trying to implementing the least case scenario
3. I’m tested this solution with POSTMAN rest api test tool.
4. This method may be complex (until we found a better one).
5. Assuming your view class is subclass of ModelViewSet class
What I’m going to do?
1. Since we can’t send the files/data in a nested fashion, we have to send it flat mode.
image-1
2. Override the __init__() method of the SubmissionSerializer serializer and dynamically add as much FileField() attribute according to the request.FILES data.
We could somehow use ListSerializer or ListField here. Unfortunately I couldn’t find out a way 🙁
# init method of "SubmissionSerializer"
def __init__(self, *args, **kwargs):
file_fields = kwargs.pop('file_fields', None)
super().__init__(*args, **kwargs)
if file_fields:
field_update_dict = {field: serializers.FileField(required=False, write_only=True) for field in file_fields}
self.fields.update(**field_update_dict)
So, what id file_fields here?
Since the form-data is a key-value pair, every file data must be associated with a key. Here in image-1, you could see file_1 and file_2.
3. Now we need to pass the file_fields values from the view. Since this operation is creating new instance, we need to override the create() method of the API class.
# complete view code
from rest_framework import status
from rest_framework import viewsets
class SubmissionAPI(viewsets.ModelViewSet):
queryset = Submission.objects.all()
serializer_class = SubmissionSerializer
def create(self, request, *args, **kwargs):
# main thing starts
file_fields = list(request.FILES.keys()) # list to be passed to the serializer
serializer = self.get_serializer(data=request.data, file_fields=file_fields)
# main thing ends
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)
4. Now, all values will be serialized properly. It’s time to override the create() method of the SubmissionSerializer() to map the relations
def create(self, validated_data):
from django.core.files.uploadedfile import InMemoryUploadedFile
validated_data_copy = validated_data.copy()
validated_files = []
for key, value in validated_data_copy.items():
if isinstance(value, InMemoryUploadedFile):
validated_files.append(value)
validated_data.pop(key)
submission_instance = super().create(validated_data)
for file in validated_files:
BinaryFile.objects.create(submission=submission_instance, file=file)
return submission_instance
5. That’s it!!!
Complete Code Snippet
# serializers.py
from rest_framework import serializers
from django.core.files.uploadedfile import InMemoryUploadedFile
class SubmissionSerializer(serializers.ModelSerializer):
def __init__(self, *args, **kwargs):
file_fields = kwargs.pop('file_fields', None)
super().__init__(*args, **kwargs)
if file_fields:
field_update_dict = {field: serializers.FileField(required=False, write_only=True) for field in file_fields}
self.fields.update(**field_update_dict)
def create(self, validated_data):
validated_data_copy = validated_data.copy()
validated_files = []
for key, value in validated_data_copy.items():
if isinstance(value, InMemoryUploadedFile):
validated_files.append(value)
validated_data.pop(key)
submission_instance = super().create(validated_data)
for file in validated_files:
BinaryFile.objects.create(submission=submission_instance, file=file)
return submission_instance
class Meta:
model = Submission
fields = '__all__'
# views.py
from rest_framework import status
from rest_framework import viewsets
class SubmissionAPI(viewsets.ModelViewSet):
queryset = Submission.objects.all()
serializer_class = SubmissionSerializer
def create(self, request, *args, **kwargs):
# main thing starts
file_fields = list(request.FILES.keys()) # list to be passed to the serializer
serializer = self.get_serializer(data=request.data, file_fields=file_fields)
# main thing ends
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)Screenhots and other stuffs
1. POSTMAN console
2. Django Shell
In [2]: Submission.objects.all()
Out[2]: <QuerySet [<Submission: Submission object>]>
In [3]: sub_obj = Submission.objects.all()[0]
In [4]: sub_obj
Out[4]: <Submission: Submission object>
In [5]: sub_obj.__dict__
Out[5]:
{'_state': <django.db.models.base.ModelState at 0x7f529a7ea240>,
'id': 5,
'issued_at': datetime.datetime(2019, 3, 27, 8, 45, 42, 193943, tzinfo=<UTC>),
'completed': False,
'atomic_id': 1}
In [6]: sub_obj.binary_files.all()
Out[6]: <QuerySet [<BinaryFile: uploads/binary/logo-800.png>, <BinaryFile: uploads/binary/Doc.pdf>, <BinaryFile: uploads/binary/invoice_2018_11_29_04_57_53.pdf>, <BinaryFile: uploads/binary/Screenshot_from_2019-02-13_16-22-53.png>]>
In [7]: for _ in sub_obj.binary_files.all():
...: print(_)
...:
uploads/binary/logo-800.png
uploads/binary/Doc.pdf
uploads/binary/invoice_2018_11_29_04_57_53.pdf
uploads/binary/Screenshot_from_2019-02-13_16-22-53.png
3. Django Admin Screenhot
