Django REST Framework Serialization of ManyRelatedField

Question

I am trying to serialize my models with Django Rest framework - http://django-rest-framework.org/

This what I want is to serialize a model with ManyToMany relation in it:

class ImageResource(models.Model):
    # Some code here
    image = models.ImageField(upload_to=upload_images_to)
    keywords = models.ManyToManyField('cards.Keyword', related_name='image_keywords', blank=True);
    # More code here

So this is my model (I removed some of the fields to help you focus on the keywords field)

My seriallizer looks something like this:

class ImageResourceSerializer(serializers.HyperlinkedModelSerializer):
    keywords = serializers.ManyRelatedField(source='keywords')

    class Meta:
        model = ImageResource
        fields = ('id', 'url', 'image', 'keywords')

And the last thing that I will show is the result from the API

{
        "id": 2, 
        "url": "http://127.0.0.1:3004/apiimageresource/2/", 
        "image": "images/1386508612-97_img-02.JPG", 

        "keywords": [
            "birthday", 
            "cake"
        ]
    },

As you see the keywords are returned as an array from strings (their names). My wish is to return them as a key value pair with their id and value:

"keywords": [
    "1":"birthday",
    "3":"cake"
]

If you know how to do this with my seriallizer I will be thankfull :)

Answer 1

Create custom serializer:

class MyKeywordsField(serializers.RelatedField):
    def to_native(self, value):
        return { str(value.pk): value.name }

Use it:

class ImageResourceSerializer(serializers.HyperlinkedModelSerializer):
    keywords = MyKeywordsField(many=True)
    # ...