python之django.db.utils.IntegrityError : NOT NULL constraint failed: polls_article. reporter_id

我在关注Django的官方documentation对于多对一关系。

创建一篇新文章，并将其添加到文章集中:

>>> new_article2 = Article.objects.create(headline="Paul's story", pub_date=date(2006, 1, 17)) 

models.py 包括:

从 django.db 导入模型

class Reporter(models.Model): 
    first_name = models.CharField(max_length=30) 
    last_name = models.CharField(max_length=30) 
    email = models.EmailField() 
 
    def __str__(self): 
        return "%s %s" % (self.first_name, self.last_name) 
 
class Article(models.Model): 
    headline = models.CharField(max_length=100) 
    pub_date = models.DateField() 
    reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE) 
 
    def __str__(self): 
        return self.headline 
 
    class Meta: 
        ordering = ('headline',) 

但是当我尝试执行时，我收到错误消息:django.db.utils.IntegrityError: NOT NULL constraint failed: polls_article.reporter_id

回溯:

    >>> new_article2 = Article.objects.create(headline="Paul's story", pub_date=datetime.date(2006, 1, 17)) 
 
Traceback (most recent call last): 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute 
    return self.cursor.execute(sql, params) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 303, in execute 
    return Database.Cursor.execute(self, query, params) 
sqlite3.IntegrityError: NOT NULL constraint failed: polls_article.reporter_id 
 
The above exception was the direct cause of the following exception: 
 
Traceback (most recent call last): 
  File "<console>", line 1, in <module> 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method 
    return getattr(self.get_queryset(), name)(*args, **kwargs) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/query.py", line 417, in create 
    obj.save(force_insert=True, using=self.db) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/base.py", line 729, in save 
    force_update=force_update, update_fields=update_fields) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/base.py", line 759, in save_base 
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/base.py", line 842, in _save_table 
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/base.py", line 880, in _do_insert 
    using=using, raw=raw) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method 
    return getattr(self.get_queryset(), name)(*args, **kwargs) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/query.py", line 1125, in _insert 
    return query.get_compiler(using=using).execute_sql(return_id) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1285, in execute_sql 
    cursor.execute(sql, params) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 100, in execute 
    return super().execute(sql, params) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute 
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers 
    return executor(sql, params, many, context) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute 
    return self.cursor.execute(sql, params) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__ 
    raise dj_exc_value.with_traceback(traceback) from exc_value 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute 
    return self.cursor.execute(sql, params) 
  File "/home/student/PycharmProjects/DjangoGetStarted/venv/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 303, in execute 
    return Database.Cursor.execute(self, query, params) 
django.db.utils.IntegrityError: NOT NULL constraint failed: polls_article.reporter_id 

请您参考如下方法:

您的模型表明 Reporter 与 Article 之间存在一对多关系，即一个 Reporter 可以与多个相关联文章。此外，由于 Article 模型的 reporter 字段不可为 null，因此每个 Article 都必须 有一个 Reporter 关联。也就是说，您必须首先创建一个 Reporter(类似于您链接到的文档中的示例):

>>> r = Reporter(first_name='John', last_name='Smith', email='john@example.com') 
>>> r.save() 

然后将您的 Article 与之相关联:

>>> a = Article(id=None, headline="This is a test", pub_date=date(2005, 7, 27), reporter=r) 
>>> a.save()