text: from django.db import models
  from osf.models.base import BaseModel, ObjectIDMixin
  from osf.utils.datetime_aware_jsonfield import DateTimeAwareJSONField
  
  
  class SchemaResponseBlock(ObjectIDMixin, BaseModel):
  
      # The SchemaResponse instance where this response originated
      source_schema_response = models.ForeignKey(
          'osf.SchemaResponse',
          null=False,
          related_name='updated_response_blocks'
      )
      # The RegistrationSchemaBlock that defines the question being answered
      source_schema_block = models.ForeignKey('osf.RegistrationSchemaBlock', null=False)
  
      # Should match source_schema_block.registration_response_key
      schema_key = models.CharField(max_length=255)
      response = DateTimeAwareJSONField(blank=True, null=True)
  
      class Meta:
          unique_together = ('source_schema_response', 'source_schema_block')
  