old_contents: from rest_framework import serializers
  
  from .models import Upload
  
  
  class UploadSerializer(serializers.ModelSerializer):
      class Meta:
          model = Upload
          fields = '__all__'
  
new_contents: from rest_framework import serializers
  
  from .models import Upload
  
  
  class UploadSerializer(serializers.ModelSerializer):
      class Meta:
          model = Upload
          fields = '__all__'
  
      def __init__(self, *args, **kwargs):
          super().__init__(*args, **kwargs)
          self.fields['guid'].required = True
  
subject: Make guid required in upload API