Using the same serializer field as PrimaryKeyRelatedField for write and as NestedSerializer Field for read

[Kaviraj Kanagaraj]

Hi Everyone,

Conside the following case

class Album(models.Model):

     name = models.CharField(max_length=20)

class Track(models.Model):

     album = models.ForeignKey(Album, related_name='tracks')

I need to create TrackSerializer,

class TrackSeriallizer(serializers.ModelSerializer):

     class Meta:

          model = Track

Here by default, album field will be treated as PrimayKeyRelatedField. So the serialized data would some like

{

  'id': 1,

  'album':1

}

but I wanted to be 

{

  'id': 1,

  'album': {

                  'id': 1,

                  'name': 'album1'

                }

}

I am aware that I could use nested serializer as below to achive this, but then I cannot create Track instance just by passing album id 

class TrackSeriallizer(serializers.ModelSerializer):

     album = AlbumSerializer()

     class Meta:

          model = Track

Can I create a TrackSerializer, so that whenever I get a list of Tracks I wants Album for the track to be nested. But while creating a Track, I should be able to pass album as id(PrimaryKeyRelation)?

Help me figuring out. Thanks in advance

[Kevin Brown]

It's probably possible to do this, but usually I would recommend just having two separate fields (as covered in this Stack Overflow answer). One holds the primary key (can be write-only) and the other is the nested serializer (usually read-only).

Most of the alternatives either require a lot of work (overriding `to_internal_value`) or result in inconsistent responses (custom serializer).

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[Kaviraj Kanagaraj]

@Kevin Thanks for your help.

I have solved this by following way,

class TrackSeriallizer(serializers.ModelSerializer):

     album = AlbumSerializer(read_only=True)

     album_id = serializers.PrimaryKeyRelatedField(queryset=Album.objects.all(), write_only=True, source='album')

     class Meta:

          model = Track

Now during listing of Tracks 'album' field will be used as nested serializer, And during create, album_id is used with source  'as album'. So that I can just pass the album_id during creation. 'source' attribute of the serializer solves the problem

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[Mingda Zhao]

THIS IS FREAKING MAGIC

[Joel Kumwenda]

This is smart solution, works like a charm.