serailizer.py

class PostListSerializer(serializers.Serializer):

    slug      = serializers.SerializerMethodField()
    title     = serializers.SerializerMethodField()
    excerpt   = serializers.SerializerMethodField()

    # get translation to generate slug, title and excerpt
    translation = None
    def get_translation(self, post):
        self.translation  = post.translations.order_by('created_at').only('title', 'content')[0]
    
    def get_title(self, obj):
        if(self.translation is None):
            self.get_translation(obj)
        return self.translation.title
    
    def get_slug(self, obj):
        if(self.translation is None):
            self.get_translation(obj)
        return slugify(self.translation.title, obj.id)

    def get_excerpt(self, obj):
        if(self.translation is None):
            self.get_translation(obj)
        return get_excerpt(self.translation.content)[:100]

    class Meta:
        fields = (
            'slug',
            'title',
            'excerpt',
            'created_at'
        )