在Django中将字段序列化为JSON对象

Question

(Django 1.8.5)
Suppose I want to print out the number of answers and distinct questions for each user.

---

models.py:

class User(models.Model):
    id = models.AutoField(db_column='Id', primary_key=True)
    nickname = models.CharField(db_column='Nickname', db_index=True, max_length=255)
    email = models.EmailField(db_column='Email', db_index=True, null=True)


class Question(models.Model):
    id = models.AutoField(db_column='Id', primary_key=True)
    user = models.ForeignKey(User, on_delete=models.CASCADE, db_column='UserId')

class Answer(models.Model):
    id = models.AutoField(db_column='Id', primary_key=True)
    question = models.ForeignKey(Question, on_delete=models.CASCADE, db_column='QuestionId')
    user = models.ForeignKey(User, on_delete=models.CASCADE, db_column='UserId')

---

views.py:

from django.db.models import Count
stats = Answer.objects.values('user').annotate(number_of_answers=Count('id'), number_of_answered_questions=Count('question', distinct=True))

---

Now,

print(stats[0])

gives me

{'number_of_answered_questions': 4, 'number_of_answers': 5, 'user': 1}

However, I would like the output to look like this:

{'number_of_answered_questions': 4, 'number_of_answers': 5, 'user': {'id':1, 'nickname': 'my_nickname'}}

What should my serializer(eg UserStatSerializer) be?

Notes:
1) I will not use the serializer for deserialization.
2) I only want to know id & nickname. Other fields such as email(actually, there are other fields as well) should not be included in the result.

Answer 1

In fact this is the default values behaviour. If you have a field called user that is a ForeignKey , the default values() call will return a dictionary key called user_id, since this is the name of the hidden model attribute that stores the actual value. When you are calling values() and passing in field names, you can pass in either user or user_id and you will get back the same thing and the dictionary key will match the field name you passed in.

You can do it manually:

for stat in stats:
     stat['user'] = User.objects.filter(id=stat['user']).values('id', 'nickname')

Check Values() doc for more details.