您正在尝试添加不可为空的字段"代理"以在没有默认值的情况下领导;我们不能这样做(数据库需要一些东西来填充现有行

Question

当我输入python management .py makemigration时，我正在制作CRM

i got this error:

你正在尝试添加一个非空字段'代理'，以导致没有默认值;我们不能那样做(数据库需要一些东西来。填充现有行)。请选择修复:

1. 现在提供一次性默认值(将在所有现有行上设置此列的空值)
退出，让我在models.py中添加一个默认值选择一个选项:

这是我的models.py:

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

class User(AbstractUser):
pass
class Lead(models.Model):
first_name = models.CharField(max_length=20)
last_name = models.CharField(max_length=20)
phone = models.BooleanField(default=False)
agent = models.ForeignKey("Agent",on_delete=models.CASCADE)

class Agent(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)

这是我的settings.py:

"""
Django settings for crm project.
Generated by 'django-admin startproject' using Django 3.1.4.
For more information on this file, see
https://docs.djangoproject.com/en/3.1/topics/settings/
For the full list of settings and their values, see
https://docs.djangoproject.com/en/3.1/ref/settings/
"""
from pathlib import Path
# Build paths inside the project like this: BASE_DIR / 'subdir'.
BASE_DIR = Path(__file__).resolve().parent.parent

# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/3.1/howto/deployment/checklist/
# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '#zi%h*+ya0z(xi6j&^3uxvv$ak3=lj5wl5&q$zh3pwv9gwk03x'
# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True
ALLOWED_HOSTS = []

# Application definition
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'leads',
]
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
]
ROOT_URLCONF = 'crm.urls'
TEMPLATES = [
{
'BACKEND': 'django.template.backends.django.DjangoTemplates',
'DIRS': [],
'APP_DIRS': True,
'OPTIONS': {
'context_processors': [
'django.template.context_processors.debug',
'django.template.context_processors.request',
'django.contrib.auth.context_processors.auth',
'django.contrib.messages.context_processors.messages',
],
},
},
]
WSGI_APPLICATION = 'crm.wsgi.application'

# Database
# https://docs.djangoproject.com/en/3.1/ref/settings/#databases
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': BASE_DIR / 'db.sqlite3',
}
}

# Password validation
# https://docs.djangoproject.com/en/3.1/ref/settings/#auth-password-validators
AUTH_PASSWORD_VALIDATORS = [
{
'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
},
{
'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
},
{
'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
},
{
'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
},
]

# Internationalization
# https://docs.djangoproject.com/en/3.1/topics/i18n/
LANGUAGE_CODE = 'en-us'
TIME_ZONE = 'UTC'
USE_I18N = True
USE_L10N = True
USE_TZ = True

# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.1/howto/static-files/
STATIC_URL = '/static/'
AUTH_USER_MODEL = 'leads.User'

Answer 1

您有两个选择:

如果您在控制台中输入2，您将退出控制台并修改您的models.py允许Lead模型下的agent字段为空值。

agent = models.ForeignKey("Agent",on_delete=models.CASCADE,null=True)

或

如果您在控制台中输入1，您可以为预先存在的行提供默认代理id。