Python 在Django模型中添加日期字段后迁移时出错

这是我的Django模型，在这个模型中，我想在原有字段之外添加另一个字段

class Offerta(models.Model):
    #old pre-existent fields
    ...
    #the field I want to add
    data_rifiuto = models.DateField(null=True, blank=True)

当我运行

'makemigrations myapp'

时没有问题，但当我运行

'migrate'

命令时，控制台显示一些

错误

：

    Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/usr/lib/python3/dist-packages/django/db/backends/sqlite3/base.py", line 337, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: NOT NULL constraint failed: myapp_offerta.data_rifiuto

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/pycharm-2017.2.3/helpers/pycharm/django_manage.py", line 43, in <module>
    run_module(manage_file, None, '__main__', True)
  File "/usr/lib/python3.5/runpy.py", line 205, in run_module
    return _run_module_code(code, init_globals, run_name, mod_spec)
  File "/usr/lib/python3.5/runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/santoryu/richiestaTesi/manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)

但是我明确地说，

null=True

编辑 类迁移（migrations.Migration）：

---

我通过删除一些迁移文件解决了这个问题。现在它开始工作了。我尝试重新运行makemigration和migrate，但没有遇到任何问题。我认为问题出在先前文件的依赖项上

您能否从

makemigrations

添加生成的迁移文件？您是否有任何未应用的迁移？您能否添加

/manage.py showmigrations

的输出？因此，删除问题或编写答案并接受它。

sqlite3.IntegrityError: NOT NULL constraint failed: myapp_offerta.data_rifiuto

    dependencies = [
    ('myapp', '0037_remove_offerta_data_rifiuto'),
    ]

    operations = [
    migrations.AddField(
        model_name='offerta',
        name='data_rifiuto',
        field=models.DateField(blank=True, null=True),
    ),
    ]