Django TypeError：“RelatedManager”对象不可迭代

在使用Django开发过程中，我们经常会遇到各种错误和异常。其中一个常见的错误是"RelatedManager"对象不可迭代的TypeError。这个错误通常出现在我们尝试在模型之间建立一对多或多对多关系时。

python
from django.db import models
class Author(models.Model):
    name = models.CharField(max_length=50)
    def __str__(self):
        return self.name
class Book(models.Model):
    title = models.CharField(max_length=50)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)
    def __str__(self):
        return self.title

python
author = Author.objects.get(name='John')
books = author.book_set
for book in books:
    print(book.title)

python
author = Author.objects.get(name='John')
books = author.book_set.all()
for book in books:
    print(book.title)