Better way to do the django api response

Question

I have tried to create a model to represent a situation like this.

each question row can have a multiple question column. there are multiple types of question column

class QuestionRow(models.Model):
   report_question = models.CharField(max_length=200)
   report_group = models.CharField(max_length=20)

class QuestionColumn(models.Model):
   header_text = models.CharField(max_length=100)
   data_type = models.CharField(max_length=10)

class QuestionItem(models.Model):
   column = models.ForeignKey(QuestionColumn)
   row = models.ForeignKey(QuestionRow)

My objective is to find the optimized way to query and return the response. where each question row in question item may or may not have multiple question columns. thinking of a way to do this using django annotate, aggregate

[{
    "report_group": 1,
    "question_row": "1a. Alarm system not active or not sufficient?",
    "question_columns" : [
        {
            "header_text": "Yes/No",
            "data_type": "Bool"
        },
        {
            "header_text": "Risk Score",
            "data_type": ""
        }
    ]
},
{
    "report_group": 1,
    "question_row": "1b. Notification system not active or inactive?",
    "question_columns" : [
        {
            "header_text": "Yes/No",
            "data_type": "Bool"
        },
        {
            "header_text": "Risk Score",
            "data_type": ""
        }
    ]
}]