Multiple file upload DRF

I have a requirement which I would like to allow multiple files to be uploaded within the same post request to create an object. I currently have a method of doing this, but after looking at some other examples it doesn't appear to be intended way to do it.

models.py

class Analyzer(models.Model):
    name = models.CharField(max_length=100, editable=False, unique=True)

class Atomic(models.Model):
    name = models.CharField(max_length=20, unique=True)

class Submission(models.Model):
    class Meta:
        ordering = ['-updated_at']

    issued_at = models.DateTimeField(auto_now_add=True, editable=False)
    completed = models.BooleanField(default=False)
    analyzers = models.ManyToManyField(Analyzer, related_name='submissions')
    atomic = models.ForeignKey(Atomic, verbose_name='Atomic datatype', related_name='submission', on_delete=models.CASCADE)

class BinaryFile(models.Model):
    class Meta:
        verbose_name = 'Binary file'
        verbose_name_plural = 'Binary files'
    def __str__(self):
        return self.file.name

    submission = models.ForeignKey(Submission, on_delete=models.CASCADE, related_name='binary_files')
    file = models.FileField(upload_to='uploads/binary/')

serializers.py

class BinaryFileSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.BinaryFile
        fields = '__all__'

class SubmissionCreateSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.Submission
        fields = ['id', 'completed', 'atomic', 'analyzers', 'binary_files']

    id = serializers.ReadOnlyField()
    completed = serializers.ReadOnlyField()

    atomic = serializers.PrimaryKeyRelatedField(many=False, queryset=models.Atomic.objects.all()
    analyzers = serializers.PrimaryKeyRelatedField(many=True, queryset=models.Analyzer.objects.all()

    binary_files = BinaryFileSerializer(required=True, many=True)

    def validate(self, data):
        # # I dont really like manually taking invalidated input!!
        data['binary_files'] = self.initial_data.getlist('binary_files')
        return data

    def create(self, validated_data):

        submission = models.Submission.objects.create(
            atomic=validated_data['atomic']
        )
        submission.analyzers.set(validated_data['analyzers'])

        # # Serialize the files - this seems too late to be doing this!
        for file in validated_data['binary_files']:
            binary_file = BinaryFileSerializer(
                data={'file': file, 'submission': submission.id}
            )

            if binary_file.is_valid():
                binary_file.save()

        return submission

Main question: While the above works, the child serializer (BinaryFileSerializer) doesn't get called until I explicitly call it in create(), which is after the validation should have occurred. Why does this never get called?

I also don't like the fact I have to manually do a self.initial_data.getlist('binary_files') and manually add it to data - this should have already been added and validated, no?

My thought is that as I defined binary_files = BinaryFileSerializer, this serializer should be called to validate that particular fields input?

FYI, I'm using the following to test POST uploads:

curl -F "binary_files=@file2.txt" -F "binary_files=@file2.txt" -F "atomic=7" -F "analyzers=12" -H "Accept: application/json; indent=4"  http://127.0.0.1:8000/api/submit/

TIA!

from Multiple file upload DRF