Django Rest Framework: Serializing Nested Objects with Custom Validation scenarios
I'm getting frustrated with I'm converting an old project and I'm trying to implement I'm working through a tutorial and I'm working with Django Rest Framework (DRF) version 3.14 and working with issues when trying to serialize nested objects with custom validation..... I have a `Book` model that has a foreign key relationship to an `Author` model. The `Author` model includes a `birth_date` that I want to validate to ensure it's not a future date. Here’s the relevant model code: ```python class Author(models.Model): name = models.CharField(max_length=100) birth_date = models.DateField() class Book(models.Model): title = models.CharField(max_length=200) author = models.ForeignKey(Author, related_name='books', on_delete=models.CASCADE) ``` To serialize this, I have created a `BookSerializer` that nests the `AuthorSerializer`. The question arises when I try to validate the `birth_date` in the `AuthorSerializer`. Here’s what I’ve implemented: ```python from rest_framework import serializers class AuthorSerializer(serializers.ModelSerializer): class Meta: model = Author fields = ['name', 'birth_date'] def validate_birth_date(self, value): if value > datetime.date.today(): raise serializers.ValidationError("Birth date want to be a future date.") return value class BookSerializer(serializers.ModelSerializer): author = AuthorSerializer() class Meta: model = Book fields = ['title', 'author'] def create(self, validated_data): author_data = validated_data.pop('author') author = Author.objects.create(**author_data) return Book.objects.create(author=author, **validated_data) ``` When I try to create a new `Book` entry with an author whose `birth_date` is set in the future, I receive the following behavior: ``` ValidationError: {'author': {'birth_date': ['Birth date want to be a future date.']}} ``` This indicates that the validation for `birth_date` is not being triggered as I expected. I've also tried using the `validate` method in the `BookSerializer`, but it still doesn't catch the behavior correctly. What am I missing? How can I ensure that the custom validation for `birth_date` works correctly when a nested object is being serialized and validated? Any guidance on best practices for handling this in DRF would be greatly appreciated. Any pointers in the right direction? I'm working with Python in a Docker container on CentOS. I've been using Python for about a year now. Any feedback is welcome! Has anyone else encountered this?