2. How to model one to many relationships?

class Article(models.Model):
    headline = models.CharField(max_length=100)
    pub_date = models.DateField()
    reporter = models.ForeignKey(User, on_delete=models.CASCADE, related_name='reporter')

    def __str__(self):
        return self.headline

    class Meta:
        ordering = ('headline',)

>>> u1 = User(username='johny1', first_name='Johny', last_name='Smith', email='johny@example.com')
>>> u1.save()
>>> u2 = User(username='alien', first_name='Alien', last_name='Mars', email='alien@example.com')
>>> u2.save()
>>> from datetime import date
>>> a1 = Article(headline="This is a test", pub_date=date(2018, 3, 6), reporter=u1)
>>> a1.save()
>>> a1.reporter.id
13
>>> a1.reporter
<User: johny1>

>>> u3 = User(username='someuser', first_name='Some', last_name='User', email='some@example.com')
>>> Article.objects.create(headline="This is a test", pub_date=date(2018, 3, 7), reporter=u1)
Traceback (most recent call last):
...
ValueError: save() prohibited to prevent data loss due to unsaved related object 'reporter'.
>>> Article.objects.create(headline="This is a test", pub_date=date(2018, 3, 7), reporter=u1)
>>> Article.objects.filter(reporter=u1)
<QuerySet [<Article: This is a test>, <Article: This is a test>]>