Direct assignment to the forward side of a many-to-many set is prohibited. Use categories.set() instead

Question

This is my model:

class Post(models.Model):
    title = models.CharField(max_length=100, blank=False, null=False)
    description = models.TextField(max_length=1000, blank=True, null=True)
    created_by = models.ForeignKey(User, on_delete=models.CASCADE, related_name='post_created_by')
    categories = models.ManyToManyField(to=Category, blank=True, related_name='categories')

This is my serializers:

class CreatePostSerializer(ModelSerializer):
    categories = serializers.CharField(error_messages={'required': "categories can't be blank"})
    title = serializers.CharField(error_messages={'required': "title can't be blank"})
    description = serializers.CharField(error_messages={'required': "description can't be blank"})

    class Meta:
        model = Post
        fields= ['title','description','categories']

    def create(self,validated_data):
        title        = validated_data['title']
        description  = validated_data['description']
        categories = validated_data['categories']
        user = self.context['request'].user
        if (title and description):
            post_obj = Post.objects.create(
                title=title, description=description, 
                created_by=user, categories=categories) 
        return validated_data

When I try to hit the API endpoint then it gives me the following error:

Direct assignment to the forward side of a many-to-many set is prohibited. Use categories.set() instead

Does this answer your question? [Direct assignment to the forward side of a many-to-many set is prohibited. Use emails\_for\_help.set() instead](https://stackoverflow.com/questions/50015204/direct-assignment-to-the-forward-side-of-a-many-to-many-set-is-prohibited-use-e) please atleast search the site before posting question. — Sunderam Dubey, Aug 20 '22 at 13:04
But why, what you have tried after looking into that question and what error do you get? — Sunderam Dubey, Aug 20 '22 at 13:47
The error is in my category field. When I try to add the category data then I get the error. — Satyajit Barik, Aug 20 '22 at 15:11
Can you edit the question with what you have tried except which has already added? — Sunderam Dubey, Aug 20 '22 at 15:33
Do you have more than one category inside validated_data? Can you please edit your question and show what you have in `categories` variable through `print(categories)`? — Sunderam Dubey, Aug 20 '22 at 15:36
Seriously, I think you should make `category` field a foreign key as generally, posts are of one category only, then the current code will work. Or else you should at least pass more than two categories from html. Since `add` and `set` method can only be used for adding queryset either in loop or by *args. — Sunderam Dubey, Aug 20 '22 at 16:26
suppose i have more than 1 category then how i have to pass the data through category id? — Satyajit Barik, Aug 20 '22 at 18:57

Direct assignment to the forward side of a many-to-many set is prohibited. Use categories.set() instead

0 Answers0