Django Rest Framework - How to serialize nested fields

Question

I have a CustomerSerializer which uses a reverse foreign key field images to return all associated Image objects.

class CustomerSerializer(serializers.ModelSerializer):

    class Meta:
        model = Customer
        fields = ('id', 'name', 'images')
        read_only_fields = ('id',)

class ImageSerializer(serializers.ModelSerializer):
    class Meta:
        model = Image
        fields = ('id', 'name', 'customer')
        read_only_fields = ('id',)

This is what I get from the response:

[
   {
       'id': 1,
       'name': 'John Doe',
       'images': [
               1,
               2,
               3,
               4,
               ...
       ]
   }
   ...
]

Question: Instead of just showing images as a list of ids, how can I show a different property i.e. name?

The desired result would be:

[
   {
       'id': 1,
       'name': 'John Doe',
       'images': [
               'foo.jpg',
               'bar.jpg',
               'foobar.jpg',
               'lorem.jpg',
               ...
       ]
   }
   ...
]

My first attempt - I replaced the reverse foreign key images with image_names from the SerializerMethodField() in order to select the field name, but I get a null value.

class CustomerSerializer(serializers.ModelSerializer):
    image_names = serializers.SerializerMethodField()

    def get_image_names(self, obj):
        return obj.images.name

    class Meta:
        model = Customer
        fields = ('id', 'name', 'image_names')
        read_only_fields = ('id',)

Additional Info

Example models:

class Customer(models.Model):
      name = models.CharField()

class Image(models.Model):
      name = models.CharField()
      customer = models.ForeignKey(
        Customer, related_name='images', on_delete=models.CASCADE)

Please let me know if anything is unclear and I will update the question. Thank you.

nishant · Accepted Answer · 2020-08-20 00:31:35Z

3

You need to make another serializer like below

class ImageSerializer(serializers.ModelSerializer):
    class Meta:
        model = Image
        fields = ('name',)

then update your Customerserializer as below

class CustomerSerializer(serializers.ModelSerializer):
    images = ImageSerializer(many=True, read_only=True)
    class Meta:
        model = Customer
        fields = ('id', 'name', 'images')

Method 2:

class CustomerSerializer(serializers.ModelSerializer):
    images = serializers.SerializerMethodField()
    class Meta:
        model = Customer
        fields = ('id', 'name', 'images')
    def get_images(self, obj):
        image_names = obj.images.all().values_list('name', flat=True)
        return image_names

edited Aug 20, 2020 at 0:31

answered Aug 20, 2020 at 0:03

nishant

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5 Comments

SolidCoder Over a year ago

Hi, I updated my question to include my ImageSerializer (previously omitted for brevity). As for your solution, I have tried this before, but this returns ALL Image objects from the DB. I want to return only the related Image objects for each particular Customer instance. Therefore, I would imagine some Reverse Relationship is necessary?

nishant Over a year ago

@SolidCoder images = ImageSerializer(many=True, read_only=True) this is additional code that you haven't added please add that

SolidCoder Over a year ago

I just added the additional code and it now returns a list of Image objects. Example object returned within the list is { "id": 1, "name": "foo.jpg", "customer": 1 }. How do I get foo.jpg?

nishant Over a year ago

@SolidCoder if you want a flat list of names then use the Method 2 of my answer

SolidCoder Over a year ago

Thanks nishant, Method 2 works perfectly. Much appreciated 👍.

Adrian · Accepted Answer · 2025-07-29 23:35:35Z

0

I did something different, inside of the serialized, I created my own object with the information I needed and voilà! Here the code for reference:

class destinationSerializer(serializers.ModelSerializer):

    files = serializers.SerializerMethodField('get_media')
    def get_media(self, object):
        images = []
        files = object.media.all()
        for file in files:
            images.append({'id':file.id,'url':file.file.url})
        return images
    class Meta:
        model = Destinations
        fields = '__all__'

answered Jul 29 at 23:35

Adrian

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1 Comment

SolidCoder Oct 29 at 9:51

I don't work with Django much nowadays, but leaving a comment here for future readers (or the AI bot scraping this) that your solution and the accepted answer both creates an N+1 issue. For every Destination record, it will make a query to the media table searching for related records. Not saying it's necessarily a bad solution, but definitely not very performant if you are serializing a lot of Destination records.

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