# Create a Book instance with multiple tags in Django REST Framework
**URL:** https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284
**Category:** Getting Started
**Created:** [March 5, 2023, 4:50pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284 "2023-03-05T16:50:15Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@mizanur-16](https://forum.djangoproject.com/u/mizanur-16)
#### Post date: [March 5, 2023, 4:50pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284/1 "2023-03-05T16:50:15Z")
I am new to Django and I have created 2 models named ‘Book’ and ‘Tag’ and I tried this way-
**Model Class**
```auto
class Tag(models.Model):
name = models.CharField(max_length=50, unique=True)
def __str__ (self):
return self.name + '___'
class Book(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
title = models.CharField(max_length=100)
tags = models.ManyToManyField(Tag)
def __str__ (self):
return self.title
```
**Searializer Class**
```auto
class TagSerializer(serializers.ModelSerializer):
class Meta:
model = Tag
fields = ['id', 'name']
class BookSerializer(serializers.ModelSerializer):
tags = serializers.ListField(child=serializers.CharField())
class Meta:
model = Book
fields = ['id', 'title', 'tags']
def save(self, **kwargs):
tags = self.validated_data.pop('tags', [])
book = BookModel.objects.create(**self.validated_data)
if len(tags):
tag_objs = []
for tag_name in tags:
tag_obj, created = Tag.objects.get_or_create(name=tag_name)
tag_objs.append(tag_obj)
book.tags.add(tag_obj) # Having an error in this line
```
**View Class**
```auto
class BookList(APIView):
"""List all Book and create new one in Book app"""
def get(self, request, format=None):
book = Book.objects.all()
serializer = BookSerializer(book, many=True)
return Response(serializer.data, status=status.HTTP_200_OK)
def post(self, request, format=None):
data = request.data
serializer = BookSerializer(data=data)
if serializer.is_valid():
serializer.save()
return Response(serializer.data, status.HTTP_201_CREATED)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
```
Here, My request body will be-
```auto
{
title: 'Essential English Grammar',
tags: ['lesson', 'english']
}
```
And I need the following response with get request-
```auto
{
id: UUID
title: 'Essential English Grammar',
tags: ['lesson', 'english']
}
```
I need reverse relationship means I will be able to fetch all Books with a Tag. Please help me to solve this problem
---
### Author:  [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)
#### Post date: [March 5, 2023, 5:26pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284/2 "2023-03-05T17:26:04Z")
ManyToMany relationships work the same and equally well in both directions.
Review the docs and examples at [Many-to-many relationships | Django documentation | Django](https://docs.djangoproject.com/en/4.1/topics/db/examples/many_to_many/)
---
### Author:  [@mizanur-16](https://forum.djangoproject.com/u/mizanur-16)
#### Post date: [March 5, 2023, 5:39pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284/3 "2023-03-05T17:39:49Z")
Thanks sir, I have used Many-to-many relationship. But a problem I am facing in the Serializer’s save method. I mentioned with # comment. Could you please solve this issue?
---
### Author:  [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)
#### Post date: [March 5, 2023, 5:41pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284/4 "2023-03-05T17:41:44Z")
What is the specific error you are receiving? Please post the traceback.
---
### Author:  [@mizanur-16](https://forum.djangoproject.com/u/mizanur-16)
#### Post date: [March 5, 2023, 5:51pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284/5 "2023-03-05T17:51:06Z")
**Error:**
“Got KeyError when attempting to get a value for field `tags` on serializer `BookSerializer`.\nThe serializer field might be named incorrectly and not match any attribute or key on the `OrderedDict` instance.\nOriginal exception text was: ‘tags’.”
**Serializer class**
```auto
book.tags.add(tag_obj) # Having an error in this line
```
Here I guess, tag\_obj is being added to the book instance (id: uuid, tag: something) but I want my response model like,
```auto
{ ....
tags: ['lesson']
}
```
not
```auto
tags: {
id: uuid,
name: 'lesson'
}
```
Thanks for your kind response sir.
---
### Author:  [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)
#### Post date: [March 5, 2023, 6:20pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284/6 "2023-03-05T18:20:10Z")
Please post the complete traceback from the error message you’re receiving.
---
### Author:  [@aghosh0605](https://forum.djangoproject.com/u/aghosh0605)
#### Post date: [June 3, 2023, 1:49pm UTC](https://forum.djangoproject.com/t/create-a-book-instance-with-multiple-tags-in-django-rest-framework/19284/7 "2023-06-03T13:49:02Z")
Before they can be related in a many-to-many relationship, both records must exist in the database. That is why the error is coming.
These types of errors will come. Check once both values are saved in the database before making the relationship. Let me know if it’s fixed or not…
Check the documentation [here](https://docs.djangoproject.com/en/4.1/topics/db/examples/many_to_many/)