Django 超级用户创建非空约束时出错失败

我已经创建了一个自定义用户模型

Student

，以修改Django提供的默认注册页面

from django.db import models
from django.contrib.auth.models import AbstractUser

class Student(AbstractUser):
    email = models.EmailField(unique=True)
    roll = models.CharField(max_length=200, blank=False)
    contact_no = models.DecimalField(
        max_digits=10, decimal_places=0, blank=False)

然后，我通过运行以下命令迁移了数据库：

python manage.py makemigrations students

python manage.py migrate

现在，当我尝试使用命令

python manage.py createsuperuser

创建超级用户时，它显示以下错误：

Traceback (most recent call last):
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/backends/sqlite3/base.py", line 296, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: NOT NULL constraint failed: students_student.contact_no

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

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/core/management/base.py", line 316, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/contrib/auth/management/commands/createsuperuser.py", line 59, in execute
    return super().execute(*args, **options)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/core/management/base.py", line 353, in execute
    output = self.handle(*args, **options)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/contrib/auth/management/commands/createsuperuser.py", line 184, in handle
    self.UserModel._default_manager.db_manager(database).create_superuser(**user_data)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/contrib/auth/models.py", line 161, in create_superuser
    return self._create_user(username, email, password, **extra_fields)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/contrib/auth/models.py", line 144, in _create_user
    user.save(using=self._db)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/contrib/auth/base_user.py", line 73, in save
    super().save(*args, **kwargs)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/models/base.py", line 717, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/models/base.py", line 747, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/models/base.py", line 830, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/models/base.py", line 868, in _do_insert
    using=using, raw=raw)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/models/query.py", line 1133, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 1285, in execute_sql
    cursor.execute(sql, params)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/backends/utils.py", line 100, in execute
    return super().execute(sql, params)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/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/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/home/anirudh/.local/share/virtualenvs/Amrita-event-manager-DHqKHtGE/lib/python3.5/site-packages/django/db/backends/sqlite3/base.py", line 296, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: NOT NULL constraint failed: students_student.contact_no

回溯（最近一次呼叫最后一次）：
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/backends/utils.py”，第85行，在执行
返回self.cursor.execute（sql，params）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/backends/sqlite3/base.py”，第296行，在execute中
返回Database.Cursor.execute（self、query、params）
sqlite3.IntegrityError:非空约束失败：学生\u学生。联系\u否
上述异常是以下异常的直接原因：
回溯（最近一次呼叫最后一次）：
文件“manage.py”，第15行，在
从命令行（sys.argv）执行命令
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/core/management/uuuu init_uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
utility.execute（）
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/core/management/__init__;.py”，执行中第375行
self.fetch_命令（子命令）。从_argv（self.argv）运行_
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/core/management/base.py”，第316行，从_argv运行
self.execute（*args，**cmd_选项）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/contrib/auth/management/commands/createsuperuser.py”，执行中第59行
return super（）.execute（*args，**选项）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/core/management/base.py”，第353行，在execute中
输出=self.handle（*args，**选项）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/contrib/auth/management/commands/createsuperuser.py”，第184行，在handle中
self.UserModel.\u default\u manager.db\u manager（数据库）.创建超级用户（**用户数据）
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/contrib/auth/models.py”，第161行，位于create_superuser中
返回self.\u创建用户（用户名、电子邮件、密码，**额外字段）
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/contrib/auth/models.py”，第144行，在_create_user中
user.save（使用=self.\u db）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/contrib/auth/base_user.py”，第73行，保存
super（）.save（*args，**kwargs）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/models/base.py”，第717行，保存
强制更新=强制更新，更新字段=更新字段）
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/db/models/base.py”，第747行，位于save_base中
更新=自我。保存表格（原始、cls、强制插入、强制更新、使用、更新字段）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/models/base.py”，第830行，在保存表格中
结果=self.\u do\u insert（cls.\u base\u manager，using，fields，update\u pk，raw）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/models/base.py”，第868行，插入
使用=使用，原始=原始）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/models/manager.py”，第82行，在manager_方法中
返回getattr（self.get_queryset（），name）（*args，**kwargs）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/models/query.py”，第1133行，插入
return query.get\u编译器（using=using）.execute\u sql（return\u id）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/models/sql/compiler.py”，第1285行，在execute_sql中
cursor.execute（sql，params）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/backends/utils.py”，第100行，执行
return super（）.execute（sql，params）
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/db/backends/utils.py”，执行中第68行
返回self.\u使用包装器执行（sql，params，many=False，executor=self.\u execute）
文件“/home/anirudh/.local/share/virtualenvs/Amrita event manager DHqKHtGE/lib/python3.5/site packages/django/db/backends/utils.py”，第77行，带包装器执行
返回执行器（sql、参数、多个、上下文）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/backends/utils.py”，第85行，在执行
返回self.cursor.execute（sql，params）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/utils.py”，第89行，在退出时__
使用exc_值的_回溯（回溯）提高dj_exc_值
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/backends/utils.py”，第85行，在执行
返回self.cursor.execute（sql，params）
文件“/home/anirudh/.local/share/virtualenvs/Amrita事件管理器DHqKHtGE/lib/python3.5/site packages/django/db/backends/sqlite3/base.py”，第296行，在execute中
返回数据
class Student(AbstractUser):
    email = models.EmailField(unique=True)
    roll = models.CharField(max_length=200, blank=False)
    contact_no = models.DecimalField(
        max_digits=10, decimal_places=0, blank=False)
    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['roll', 'contact_no',] # By doing so create superuser command will ask their input

from django.contrib.auth.models import BaseUserManager, AbstractUser
from django.db import models
from django.utils import timezone

class UserManager(BaseUserManager):
      def _create_user(self, email, password, **extra_fields):
            """Create and save a User with the given email and password."""
          if not email:
                raise ValueError('The email must be set')
          if not password:
                raise ValueError('The password must be set')
          email = self.normalize_email(email)
          user = self.model(email=email, **extra_fields)
          user.set_password(password)
          user.save(using=self._db)
          return user
      def create_superuser(self, email, password, **extra_fields):
        """Create and save a SuperUser with the given email and password."""
          extra_fields.setdefault('is_staff', True)
          extra_fields.setdefault('is_superuser', True)
          extra_fields.setdefault('roll', YOUR DESIRE VALUE )
          extra_fields.setdefault('contact_no', YOUR DESIRE VALUE)
          if extra_fields.get('is_staff') is not True:
              raise ValueError('Superuser must have is_staff=True.')
          if extra_fields.get('is_superuser') is not True:
              raise ValueError('Superuser must have is_superuser=True.')
          super_user = self._create_user(email, password, **extra_fields)
          return super_user

class Student(AbstractUser):
     email = models.EmailField(unique=True)
     roll = models.CharField(max_length=200, blank=False)
     contact_no = models.DecimalField(
       max_digits=10, decimal_places=0, blank=False)
     objects = UserManager()
     USERNAME_FIELD = 'email'