CODEWITHSUNDEEP
pythondjangorestdjango-rest-frameworkdjango-serializer
Umut Çağdaş Coşkun
Umut Çağdaş Coşkun

Reputation: 1472

Retrieve related field's object in GET requests, otherwise use only ID of the object in POST, PUT, DELETE etc

I have two serializers. The 'category' field in the Article is a ForeignKey.

I want to retrieve category object completely when I do a GET request. And I want to use only ID of the category when I do a POST, PUT or DELETE request.

class CategorySerializer(serializers.ModelSerializer):
    class Meta:
        model = Category
        fields = ('pk', 'name', 'slug')

class ArticleSerializer(serializers.ModelSerializer):
    class Meta:
        model = Article
        fields = ('pk', 'title', 'slug', 'body', 'category')
        depth = 1

If I add the "depth = 1" property to the Meta class, then I'm getting the category object. It's OK.

But, if I try to add new Article (via POST request) I'm getting this error:

IntegrityError at /api/articles
NOT NULL constraint failed: panel_article.category_id

If I try with defining a CategorySerializer field, instead of use 'depth' property like this:

class ArticleSerializer(serializers.ModelSerializer):
    category = CategorySerializer()

    class Meta:
        model = Article
        fields = ('pk', 'title', 'slug', 'body', 'category')

I'm getting this error due to category field:

"Invalid data. Expected a dictionary, but got int."

I guess DRF is trying to create new category, when I try to create a new Article.

How do I solve this problem?

Upvotes: 3

Views: 1438

Answers (1)

Ivan Semochkin
Ivan Semochkin

Reputation: 8897

It is a common problem, every time when you want to change representation behavior you are free to use to_representation method of a serializer: 

class ArticleSerializer(serializers.ModelSerializer):

    class Meta:
        model = Provider
        fields = ('pk', 'title', 'slug', 'body', 'category')

    def to_representation(self, instance):
        representation = super(ArticleSerializer, self).to_representation(instance)
        representation['category'] = CategorySerializer(instance.category).data
        return representation

Upvotes: 4

Related Questions