Django foreign key rest framework

Question

Is there any way to display the name of the user in the "likedBy" section of the view, instead of the user id? Using django rest framework From view I get , ignore comments:

[
    {
        "id": 3,
        "title": "ddsa",
        "content": "dsadsa",
        "created": "2021-02-10T08:07:42.758400Z",
        "updated": "2021-02-10T08:07:42.758400Z",
        "author": 1,
        "category": [
            {
                "pk": 1,
                "name": "Life"
            }
        ],
        "likedBy": [
            1
        ],
        "comments": [
            {
                "id": 2,
                "content": "ghfa",
                "created": "2021-02-10T08:08:02.407950Z",
                "post": 3,
                "author": 1,
                "likedBy": [
                    1
                ]
            }
        ]
    }
]

Views.py:

class PostViewSet(FlexFieldsMixin, generics.ListAPIView):
    queryset = Post.objects.all()
    serializer_class = PostSerializer
    permit_list_expands = ['category', 'comments']

Models.py


class Post(models.Model):
    title = models.CharField(max_length=255)
    content = models.TextField()
    category = models.ManyToManyField(Category, related_name='posts')
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    likedBy = models.ManyToManyField(User, related_name='posts', blank=True)

    class Meta:
        ordering = ['-created']

Serializers.py:


class PostSerializer(FlexFieldsModelSerializer):
    class Meta:
        model = Post
        fields = '__all__'
        expandable_fields = {
            'category': ('blogApi.CategorySerializer', {'many': True}),
            'comments': ('blogApi.CommentSerializer', {'many': True}),
        }

How serialize ManyToMany field to display text values

possibly duplicate https://stackoverflow.com/questions/17280007/retrieving-a-foreign-key-value-with-django-rest-framework-serializers — rahul.m, Feb 10 '21 at 10:52

score 1 · Accepted Answer · answered Feb 10 '21 at 12:53

Given that you are not serializing a relation, but rather an attribute of your model which is related to your user, I believe you have to use a serializer.SerializerMethodField(). This allows you to do the following:

class PostSerializer(FlexFieldsModelSerializer):
    liked_by = serializers.SerializerMethodField(method_name="get_user_likes")

    class Meta:
        model = Post
        fields = (
            "title",
            "content",
            "category",
            "author",
            "created",
            "update",
            "liked_by"
        )
        expandable_fields = {
            'category': ('blogApi.CategorySerializer', {'many': True}),
            'comments': ('blogApi.CommentSerializer', {'many': True}),
        }

    @classmethod
    def get_user_likes(obj):
       # do whatever you like here, but I tend to call a 
       # method on my model to keep my serializer file
       # nice and tidy
       # you'll need to define a UserSerializer
       return UserSerializer(obj.get_user_likes(), many=True, read_only=True)

And in your Post model:

class Post(models.Model):
    title = models.CharField(max_length=255)
    content = models.TextField()
    category = models.ManyToManyField(Category, related_name='posts')
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    likedBy = models.ManyToManyField(User, related_name='posts', blank=True)

    class Meta:
        ordering = ['-created']

    def get_user_likes(self):
        return self.likedBy.all()

You can of course define the full method in your serializer, but as I said I like to keep the serializer as clean as possible and put all methods associated with models in my models.py.

    @classmethod
    def get_user_likes(obj):
       # you'll need to define a UserSerializer
       return UserSerializer(obj.likedBy.all(), many=True, read_only=True)

score 0 · Answer 2 · answered Feb 10 '21 at 12:59

So you can set

likedBy = serializers.ReadOnlyField(source='get_likedBy')

in your PostSerializer class and define function in your Post model class like below:

@property
def get_likedBy(self):
   liked_by = []
   for user in self.users_liked_post.all():
       liked_by.append(user.name)
   return liked_by

just use correct related_name instead of users_liked_post

Paul Tuckett · Answer 3 · 2021-02-10T13:46:56.217

If you add likedBy to your expandable fields, and then add ?expand=likedBy to your url, it should give you all the information that you outline in the UserSerializer, or write a new serializer named LikedBySerializer. Also as a general rule, try not to use '__all__' it's a good way to leak data. Happy coding!

class LikedBySerializer(FlexFieldsModelSerializer):
    class Meta:
        model = User
        fields = '__all__'


class PostSerializer(FlexFieldsModelSerializer):
    class Meta:
        model = Post
        fields = '__all__'
        expandable_fields = {
            'category': ('blogApi.CategorySerializer', {'many': True}),
            'comments': ('blogApi.CommentSerializer', {'many': True}),
            'likedBy': ('blogApi.LikedBySerializer', {'many': True}),
        }

Django foreign key rest framework

3 Answers3