How to exclude some fields in nested (related models) fields?

[sandnima]

For instance:

# types
...

class CategoryType(DjangoObjectType):
    class Meta:
        model = Brand
        fields = ("name", "detail")

class BookType(DjangoObjectType):
    class Meta:
        model = Book
        fields = ("title", "category", "other_fields")

# queries
...

class CategoriesQuery(graphene.ObjectType):
    categories = graphene.List(CategoryType)
    
    @staticmethod
    def resolve_category_list(root, info):
        return Category.objects.all()

class BooksQuery(graphene.ObjectType):
    books= graphene.List(BookType)
    
    @staticmethod
    def resolve_book_list(root, info):
        return Book.objects.all()

How can I exclude detail field querying book list,
without excluding in CategoryType itself (which may be used in other queries like category list)?

[sjdemartini]

If you only need to prevent detail from being returned in your client query, then that's general GraphQL query functionality, like:

books {
  title
  category {
    name
    # don't include `detail` here and it won't be returned
  }
}

If you want to disallow clients requesting the detail field of category when querying books, you could presumably create a separate type that's only used to specify as the resolved field for category in the BookType, like:

class CategoryType(DjangoObjectType):
    class Meta:
        model = Brand
        fields = ("name", "detail")

class CategoryTypeRestricted(DjangoObjectType):
    class Meta:
        model = Brand
        fields = ("name",)  # Exclude the "detail" field

class BookType(DjangoObjectType):
    category = CategoryTypeRestricted()   # Reference the restricted type
    class Meta:
        model = Book
        fields = ("title", "category", "other_fields")