django初学

Django安装

1、安装django库

pip install Django

2、自动生成项目

django-admin startproject HelloWorld

3、启动项目

python manage.py runserver 0.0.0.0:8000

4、生成模块

django-admin startapp TestModel

5、配置连接多个MySQL数据库

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    },
    'zwfw': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'zwfw', # 数据库名称
        'HOST': '192.168.1.6', # 数据库地址，本机 ip 地址 127.0.0.1
        'PORT': 3306, # 端口
        'USER': 'root_DB',  # 数据库用户名
        'PASSWORD': 'password', # 数据库密码
    },
    'linyi': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'linyi', # 数据库名称
        'HOST': '192.168.1.6', # 数据库地址，本机 ip 地址 127.0.0.1
        'PORT': 3306, # 端口
        'USER': 'root_DB',  # 数据库用户名
        'PASSWORD': 'password', # 数据库密码
    },
}

修改mysql对应配置路由

# 配置数据库操作路由
DATABASE_ROUTERS = ['pyetl1.database_router.DatabaseAppsRouter']

DATABASE_APPS_MAPPING = {
    'wuliu': 'zwfw',
    'yingxiao': 'linyi',
    'sdlinyi': 'sd_linyi',
}

生成指定MySQL模型models文件

python manage.py inspectdb --database=linyi > yingxiao/models.py

简单的MySQL操作

from django.http import HttpResponse

from wuliu.models import RegionManage


# 数据库操作
def testdb(request):
    test1 = RegionManage(row_id=1)
    test1.save()
    return HttpResponse("<p>数据添加成功！</p>")


# 查询全部数据
def getdataall(request):
    # 初始化
    response = ""
    response1 = ""

    listTest = RegionManage.objects.all()

    # filter相当于SQL中的WHERE，可设置条件过滤结果
    # response2 = RegionManage.objects.filter(id=1)

    # 获取单个对象
    # response3 = RegionManage.objects.get(id=1)

    # 限制返回的数据 相当于 SQL 中的 OFFSET 0 LIMIT 2;
    # RegionManage.objects.order_by('name')[0:2]

    # 数据排序
    # RegionManage.objects.order_by("id")

    # 上面的方法可以连锁使用
    # RegionManage.objects.filter(name="runoob").order_by("id")

    # 输出所有数据
    for var in listTest:
        response1 += var.operateusername
    response = response1
    return HttpResponse("<p>" + response + "</p>")


# 更新数据
def updatedatabyid(request):
    # 修改其中一个id=1的name字段，再save，相当于SQL中的UPDATE
    test1 = RegionManage.objects.get(row_id=1)
    test1.operateusername = '测试组织机构'
    test1.save()

    # 另外一种方式
    # Test.objects.filter(id=1).update(name='Google')

    # 修改所有的列
    # Test.objects.all().update(name='Google')

    return HttpResponse("<p>修改成功</p>")


# 删除数据
def deldata(request):
    # 删除id=1的数据
    test1 = RegionManage.objects.get(row_id=1)
    test1.delete()

    # 另外一种方式
    # Test.objects.filter(id=1).delete()

    # 删除所有数据
    # Test.objects.all().delete()

    return HttpResponse("<p>删除成功</p>")

以下是学习过程中遇到的问题

1、启动的时候报错

You have 18 unapplied migration(s). Your project may not work properly until you apply

将服务关闭后执行以下代码，然后启动就正常了

python manage.py migrate

2、MySQL版本问题

Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    main()
  File "manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "D:\software\anaconda\envs\data\lib\site-packages\django\core\management\__init__.py", line 442, in execute_from_command_line
    utility.execute()
  File "D:\software\anaconda\envs\data\lib\site-packages\django\core\management\__init__.py", line 436, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "D:\software\anaconda\envs\data\lib\site-packages\django\core\management\base.py", line 412, in run_from_argv
    self.execute(*args, **cmd_options)
  File "D:\software\anaconda\envs\data\lib\site-packages\django\core\management\base.py", line 458, in execute
    output = self.handle(*args, **options)
  File "D:\software\anaconda\envs\data\lib\site-packages\django\core\management\commands\inspectdb.py", line 46, in handle
    for line in self.handle_inspection(options):
  File "D:\software\anaconda\envs\data\lib\site-packages\django\core\management\commands\inspectdb.py", line 62, in handle_inspection
    with connection.cursor() as cursor:
  File "D:\software\anaconda\envs\data\lib\site-packages\django\utils\asyncio.py", line 26, in inner
    return func(*args, **kwargs)
  File "D:\software\anaconda\envs\data\lib\site-packages\django\db\backends\base\base.py", line 330, in cursor
    return self._cursor()
  File "D:\software\anaconda\envs\data\lib\site-packages\django\db\backends\base\base.py", line 306, in _cursor
    self.ensure_connection()
  File "D:\software\anaconda\envs\data\lib\site-packages\django\utils\asyncio.py", line 26, in inner
    return func(*args, **kwargs)
  File "D:\software\anaconda\envs\data\lib\site-packages\django\db\backends\base\base.py", line 289, in ensure_connection
    self.connect()
  File "D:\software\anaconda\envs\data\lib\site-packages\django\utils\asyncio.py", line 26, in inner
    return func(*args, **kwargs)
  File "D:\software\anaconda\envs\data\lib\site-packages\django\db\backends\base\base.py", line 272, in connect
    self.init_connection_state()
  File "D:\software\anaconda\envs\data\lib\site-packages\django\db\backends\mysql\base.py", line 257, in init_connection_state
    super().init_connection_state()
  File "D:\software\anaconda\envs\data\lib\site-packages\django\db\backends\base\base.py", line 239, in init_connection_state
    self.check_database_version_supported()
  File "D:\software\anaconda\envs\data\lib\site-packages\django\db\backends\base\base.py", line 214, in check_database_version_supported
    raise NotSupportedError(
django.db.utils.NotSupportedError: MySQL 8 or later is required (found 5.7.43).

找到下面文件，找到对应行，注释掉以后就正常了。

# \Lib\site-packages\django\db\backends\base\base.py
# 搜索下面方法
# 注释掉代码

 check_database_version_supported()

3、生成models运行查询代码报错，id缺少key配置。

yingxiao.TAjxzsCxlatzs: (models.E004) 'id' can only be used as a field name if the field also sets 'primary_key=True'.

找到对应yingxiao.TAjxzsCxlatzs:类，在id后添加   primary_key=True