Python django中用户\u id\u id的默认值无效

我是django的新手，我正在创建我的模型，但在尝试向另一个模型添加外键时遇到了问题。以下是我的模型：

from django.db import models

class User(models.Model):
    user_id = models.CharField(max_length=10, primary_key=True)
    name = models.CharField(max_length=30)
    surname = models.CharField(max_length=30)
    role = models.CharField(max_length=10)
    address = models.CharField(max_length=50)
    email = models.EmailField(max_length=30)
    password = models.CharField(max_length=20)
    phone = models.IntegerField()
    GPA = models.FloatField(max_length=5)
    Gender = models.CharField(max_length=1)

    def __str__(self):
        return self.user_id


class Login(models.Model):
    user_id = models.ForeignKey(User, on_delete=models.CASCADE,  default='00000')
    email = models.EmailField(max_length=30)
    password = models.CharField(max_length=20)

    def __str__(self):
        return self.email

当我键入makemigrations时，我得到以下信息：

You are trying to change the nullable field 'user_id' on login to non-nullable without a default; we can't do that (the database needs something to populate existing rows).
Please select a fix:
 1) Provide a one-off default now (will be set on all existing rows)
 2) Ignore for now, and let me handle existing rows with NULL myself (e.g. because you added a RunPython or RunSQL operation to handle NULL values in a previous data migration)
 3) Quit, and let me add a default in models.py
Select an option:  3

因此，我添加了一个默认值，但在尝试迁移时出现了此错误。我试图将user_id从user更改为AutoField，这样我就不必添加任何默认值，但它仍然给我这个错误。另外，我也不知道为什么它最后会说user_id_id。有人能帮我解决这个问题吗

    Running migrations:
      Rendering model states... DONE
      Applying login.0003_login_user_id...Traceback (most recent call last):
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 64, in execute
        return self.cursor.execute(sql, params)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\mysql\base.py", line 112, in execute
        return self.cursor.execute(query, args)
      File "C:\User\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 226, in execute
        self.errorhandler(self, exc, value)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 42, in defaulterrorhandler
        raise errorvalue
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 223, in execute
        res = self._query(query)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 379, in _query
        rowcount = self._do_query(q)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 342, in _do_query
        db.query(q)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 286, in query
        _mysql.connection.query(self, query)
    _mysql_exceptions.OperationalError: (1067, "Invalid default value for 'user_id_id'")

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

    Traceback (most recent call last):
      File "C:\Program Files (x86)\JetBrains\PyCharm 5.0.4\helpers\pycharm\django_manage.py", line 41, in <module>
        run_module(manage_file, None, '__main__', True)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\runpy.py", line 182, in run_module
        return _run_module_code(code, init_globals, run_name, mod_spec)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\runpy.py", line 96, in _run_module_code
        mod_name, mod_spec, pkg_name, script_name)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\runpy.py", line 85, in _run_code
        exec(code, run_globals)
      File "C:/Users/Desktop/Project/TSL/mysite\manage.py", line 10, in <module>
        execute_from_command_line(sys.argv)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\__init__.py", line 353, in execute_from_command_line
        utility.execute()
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\__init__.py", line 345, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\base.py", line 348, in run_from_argv
        self.execute(*args, **cmd_options)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\base.py", line 399, in execute
        output = self.handle(*args, **options)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\commands\migrate.py", line 200, in handle
        executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 92, in migrate
        self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_initial)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 121, in _migrate_all_forwards
        state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 198, in apply_migration
        state = migration.apply(state, schema_editor)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\migration.py", line 123, in apply
        operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\operations\fields.py", line 62, in database_forwards
        field,
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\mysql\schema.py", line 50, in add_field
        super(DatabaseSchemaEditor, self).add_field(model, field)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\base\schema.py", line 396, in add_field
        self.execute(sql, params)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\base\schema.py", line 110, in execute
        cursor.execute(sql, params)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 79, in execute
        return super(CursorDebugWrapper, self).execute(sql, params)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 64, in execute
        return self.cursor.execute(sql, params)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\utils.py", line 95, in __exit__
        six.reraise(dj_exc_type, dj_exc_value, traceback)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\utils\six.py", line 685, in reraise
        raise value.with_traceback(tb)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 64, in execute
        return self.cursor.execute(sql, params)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\mysql\base.py", line 112, in execute
        return self.cursor.execute(query, args)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 226, in execute
        self.errorhandler(self, exc, value)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 42, in defaulterrorhandler
        raise errorvalue
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 223, in execute
        res = self._query(query)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 379, in _query
        rowcount = self._do_query(q)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 342, in _do_query
        db.query(q)
      File "C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 286, in query
        _mysql.connection.query(self, query)
    django.db.utils.OperationalError: (1067, "Invalid default value for 'user_id_id'")

    Process finished with exit code 1

运行迁移：
正在渲染模型状态。。。完成
正在应用login.0003\u login\u user\u id…回溯（最近一次呼叫最后一次）：
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\backends\utils.py”，第64行，在execute中
返回self.cursor.execute（sql，params）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\backends\mysql\base.py”，第112行，在execute中
返回self.cursor.execute（查询，参数）
文件“C:\User\AppData\Local\Programs\Python\Python35-32\lib\site packages\MySQLdb\cursors.py”，第226行，在execute中
errorhandler（self、exc、value）
defaulterrorhandler中的文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\MySQLdb\connections.py”，第42行
提高错误值
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\MySQLdb\cursors.py”，第223行，在execute中
res=自我查询（查询）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\MySQLdb\cursors.py”，第379行，在查询中
rowcount=self.\u do\u查询（q）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\MySQLdb\cursors.py”，第342行，在查询中
数据库查询（q）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\MySQLdb\connections.py”，第286行，在查询中
_mysql.connection.query（self，query）
_mysql_exceptions.OperationalError:（1067，“用户id的默认值无效”）
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“C:\Program Files（x86）\JetBrains\PyCharm 5.0.4\helpers\PyCharm\django_manage.py”，第41行，在
运行\u模块（管理\u文件，无，'.\u主\u'，真）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\runpy.py”，第182行，在run\u模块中
返回\u运行\u模块\u代码（代码、初始化全局、运行\u名称、模块规格）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\runpy.py”，第96行，在运行模块代码中
模块名称、模块规格、组件名称、脚本名称）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\runpy.py”，第85行，在运行代码中
exec（代码、运行\全局）
文件“C:/Users/Desktop/Project/TSL/mysite\manage.py”，第10行，在
从命令行（sys.argv）执行命令
文件“C:\Users\AppData\Local\Programs\Python\Python 35-32\lib\site packages\django\core\management\\uuuuuu init\uuuuuu.py”，第353行，从命令行执行
utility.execute（）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\django\core\management\\uuuu init\uuuu.py”，执行中第345行
self.fetch_命令（子命令）。从_argv（self.argv）运行_
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\django\core\management\base.py”，第348行，从\u argv运行
self.execute（*args，**cmd_选项）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\core\management\base.py”，第399行，在execute中
输出=self.handle（*args，**选项）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\django\core\management\commands\migrate.py”，第200行，位于句柄中
executor.migrate（目标、计划、假=假、假首字母=假首字母）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\django\db\migrations\executor.py”，第92行，在migrate中
self.\u迁移\u所有\u转发（计划、完整计划、假=假、假首字母=假首字母）
文件“C:\Users\AppData\Local\Programs\Python\Python 35-32\lib\site packages\django\db\migrations\executor.py”，第121行，全部向前迁移
state=self.apply\u迁移（state，migration，false=false，false\u initial=false\u initial）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\django\db\migrations\executor.py”，第198行，在apply\u migration中
state=migration.apply（状态，模式编辑器）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\migrations\migration.py”，第123行，在apply中
操作。数据库转发（self.app\u标签、模式编辑器、旧状态、项目状态）
数据库中第62行的文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\site packages\django\db\migrations\operations\fields.py”
领域
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\backends\mysql\schema.py”，第50行，在add\u字段中
super（DatabaseSchemaEditor，self）.add_字段（model，field）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\backends\base\schema.py”，第396行，在添加字段中
self.execute（sql，params）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\backends\base\schema.py”，第110行，在execute中
cursor.execute（sql，params）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\backends\utils.py”，第79行，在execute中
返回super（CursorDebugWrapper，self）.execute（sql，params）
文件“C:\Users\AppData\Local\Programs\Python35-32\lib\site packages\django\db\backends\utils.py”，第64行，在execute中
返回self.cursor.execute（sql，params）
文件“C:\Users\AppData\Local\Programs\Python\Python35-32\lib\
from django.db import models

# Renamed from User to MyUser,
# User is a built-in model that comes with django
# and is used when logging people into the system
# https://docs.djangoproject.com/en/1.9/topics/auth/default/

class MyUser(models.Model):
    name = models.CharField(max_length=30)
    surname = models.CharField(max_length=30)
    role = models.CharField(max_length=10)
    address = models.CharField(max_length=50)
    email = models.EmailField() # email field doesn't need max_length
    password = models.CharField(max_length=20)
    phone = models.CharField(max_length=30) # this should be a CharField
    GPA = models.FloatField()
    gender = models.CharField(max_length=1,
                              choices=(('M', 'Male',),
                                       ('F', 'Female',),
                                       ('X', 'Prefer not to disclose',)))