How do you create object with modelviewset and POST request?

Question

Im trying to add a comment to my db, but getting error 'OrderedDict' object has no attribute 'pk'

The part of react.js code handling the POST request:

addComment() {
    let url = this.props.post_url

    axios.post('/api/comments/', {
          post: url,
          user: "http://127.0.0.1:8000/api/users/1/?format=json",
          text: document.getElementsByName(url)[0].value,
          csrfmiddlewaretoken: document.getElementsByName("csrfmiddlewaretoken")[0].value},
      )
    .then(function (response) {
       console.log(response);
    })
    .catch(function (error) {
      console.log(error);
    });

}

My serializers.py:

from django.contrib.auth.models import User
from rest_framework import serializers

from .models import Post, Comment

        
class UserSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'username', 'url')


class CommentSerializer(serializers.HyperlinkedModelSerializer):
    #user = UserSerializer(many=False, required=False)
    class Meta:
        model = Comment
        fields = ('id', "post", "user", 'text')
        read_only_fields = ('id', "user")

    def create(self):
        user = None   
        request = self.context.get("request")
        if request and hasattr(request, "user"):
            user = request.user


class PostSerializer(serializers.HyperlinkedModelSerializer):
    #user = UserSerializer(required=False)
    comments = CommentSerializer(many=True, required=False, read_only=True)
    class Meta:
        model = Post
        fields = ('id', 'title', "user", "url", "comments", 'text')
        read_only_fields = ('id', "url", "comments")

    def save(self):
        user = None
        request = self.context.get("request")
        if request and hasattr(request, "user"):
            user = request.user

My views.py

from django.contrib.auth.models import User
from api.serializers import UserSerializer
from rest_framework import viewsets

from .models import Comment, Post
from .serializers import CommentSerializer, PostSerializer


class UserViewSet(viewsets.ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer

        
class CommentViewSet(viewsets.ModelViewSet):
    queryset = Comment.objects.all()
    serializer_class = CommentSerializer

       
class PostViewSet(viewsets.ModelViewSet):
    queryset = Post.objects.all()
    serializer_class = PostSerializer

When sending the Post-request it goes througth normaly. If I remove one of the fields it returnes a 400. Now Im getting this 500 [Internal server] error.

AttributeError: 'OrderedDict' object has no attribute 'pk'

The error seems to be comming from:

/home/halvor1606/.virtualenvs/django-react/local/lib/python2.7/site-packages/rest_framework/relations.py in get_url

   # Unsaved objects will not yet have a valid URL.

   if hasattr(obj, 'pk') and obj.pk in (None, ''):

       return None

Here-> lookup_value = getattr(obj, self.lookup_field) ...

   kwargs = {self.lookup_url_kwarg: lookup_value}

   return self.reverse(view_name, kwargs=kwargs, request=request, format=format)

   def get_name(self, obj):

       return six.text_type(obj)

▶ Local vars are as follows:-

Variable    Value

request      <rest_framework.request.Request object at 0x7f4e59e75b90>

view_name    'post-detail'

obj           OrderedDict([(u'title', u'adskjfj|'), (u'user', <User:      halvor1606>), (u'text', u'kjkldsjf')])

self          HyperlinkedIdentityField(read_only=True, view_name='post-detail')

format        None

Read the other Questions with the same error. Didn't find one that solved my problem.

Thank you!

Edit:

Solved it by adding this to my post serializer:

def create(self, validated_data):
    tmp_post = validated_data
    user = None   

    request = self.context.get("request")
    if request and hasattr(request, "user"):
        user = request.user

    post = Post.objects.create(
        user=user,
        title=tmp_post['title'],
        text=tmp_post['text'],
    )

    return post

Answer 1

I think this is simply because your url here is empty:

addComment() {
    let url = this.props.post_url

    axios.post('/api/comments/', {
          post: url,
          user: "http://127.0.0.1:8000/api/users/1/?format=json",
          text: document.getElementsByName(url)[0].value,
          csrfmiddlewaretoken: document.getElementsByName("csrfmiddlewaretoken")[0].value},
      )
    .then(function (response) {
       console.log(response);
    })
    .catch(function (error) {
      console.log(error);
    });
}

Since you specified class CommentSerializer(serializers.HyperlinkedModelSerializer):, this was mentioned in the document:

There needs to be a way of determining which views should be used for hyperlinking to model instances.

By default hyperlinks are expected to correspond to a view name that matches the style '{model_name}-detail', and looks up the instance by a pk keyword argument.

So the HyperlinkedModelSerializer tries to find a view which should be used for the linking to Post object and could not find it. Highly suspected that the post url is with empty id