everyone.
What I want is get field of a related model by serializer.
I have 2 models:

```
class Question(models.Model):
    question_text = models.CharField(max_length=200)
    def __str__(self):
        return self.question_text    

class Test(models.Model):
    test_name = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    question = models.ManyToManyField(Question, related_name='tests')
    def __str__(self):
        return self.test_name

```

Why I've used ManyToManyField?
Because I've followed here:
<https://medium.com/django-rest/lets-build-a-basic-product-review-backend-with-drf-part-1-652dd9b95485>

Now I can do smth like:
[![enter image description here](https://i.stack.imgur.com/q3w4Y.png)](https://i.stack.imgur.com/q3w4Y.png)

But I want get question\_text in response.
What I tried:

```
class TestSerializer(serializers.HyperlinkedModelSerializer):
    question_text = serializers.CharField(read_only=True, source="question.question_text")
    class Meta:
        model = Test
        fields = ['pk', 'test_name', 'pub_date', 'question_text']
        expandable_fields = {
 'question': (QuestionSerializer, {'many': True})
}

```

But it returned:

[![enter image description here](https://i.stack.imgur.com/zSk3k.png)](https://i.stack.imgur.com/zSk3k.png)

I understand, that problem might be in DB relations, but I can't get it.
Thanks in advance!