# 1000、Django错误 ### 错误： no such table: auth\_user ```bash python manage.py migrate python manage.py createsuperuser ``` *** \##　错误： return database\_name == ':memory:' or 'mode=memory' in database\_name ```bash DATABASES = { 'default': { 'ENGINE': 'django.db.backends.sqlite3', 'NAME': str(BASE_DIR / 'db.sqlite3'), } } ``` *** Django3+celery4.4报错DatabaseWrapper objects created in a thread can only be used in that same thread. **执行异步任务时报错：** django.db.utils.DatabaseError: DatabaseWrapper objects created in a thread can only be used in that same thread. The object with alias 'default' was created in thread id 2068603070080 and this is thread id 2069065236128. 解决方法： 原先启动命令： ```python windows: celery -A xxx worker -l info -P eventlet 可能需安装 eventlet Linux: celery -A xxx worker -l info ``` 替换为： ```python windows: celery -A xxx worker -l info -P eventlet --pool=solo Linux: celery -A xxx worker -l info --pool=solo ``` ### 解决django同步数据库的时候app models表没有成功创建的问题 问题描述： * 在django中创建了一个app，而且在app中自定义创建了几个数据表，在同步的时候系统自带的表可以成功， 但是 models 中的没有生效，而且进入对应 app下的migrations目录，发现为空，应该如何解决呢！ 解决方式： ```python python3 manage.py makemigrations --empty app_name # app_name 就是你的app名字，此处要写成自己的app名字 python3 manage.py makemigrations # 再次正常运行生成迁移文件的命令 python3 manage.py migrate # 同步数据库 ``` 然后就会看到成功了！ ### SQLite 版本库错误 ```bash File "/home/celery/venv/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 65, in check_sqlite_version raise ImproperlyConfigured('SQLite 3.8.3 or later is required (found %s).' % Database.sqlite_version) django.core.exceptions.ImproperlyConfigured: SQLite 3.8.3 or later is required (found 3.7.17). ``` 两个解决办法 方法一：给Django降级 ```bash pip install django==2.1.7 ``` 方法二：升级SQLite > 下载地址： ```bash # 链接最好重新获取，否则可能不是最新版本 wget https://www.sqlite.org/2019/sqlite-autoconf-3300100.tar.gz tar zxvf sqlite-autoconf-3300100.tar.gz cd sqlite-autoconf-3300100/ ./configure make & make install # 查看新旧版本 /usr/local/bin/sqlite3 --version /usr/bin/sqlite3 --version # 更换 mv /usr/bin/sqlite3 /usr/bin/sqlite3_old ln -s /usr/local/bin/sqlite3 /usr/bin/sqlite3 # 当前环境变量库 export LD_LIBRARY_PATH="/usr/local/lib" ``` 检查Python的SQLite3版本 ```python (application) [root@localhost application]# python Python 3.6.5 (default, Jul 9 2019, 20:03:55) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux Type "help", "copyright", "credits" or "license" for more information. >>> import sqlite3 >>> sqlite3.sqlite_version '3.30.1' >>> exit() ``` ### Django3+celery4.4报错DatabaseWrapper objects created in a thread can only be used in that same thread. 执行异步任务时报错： django.db.utils.DatabaseError: DatabaseWrapper objects created in a thread can only be used in that same thread. The object with alias 'default' was created in thread id 2068603070080 and this is thread id 2069065236128. 解决方法： 原先启动命令： ```python windows: celery -A xxx worker -l info -P eventlet 可能需安装 eventlet Linux: celery -A xxx worker -l info ``` 替换为： ```python windows: celery -A xxx worker -l info -P eventlet --pool=solo Linux: celery -A xxx worker -l info --pool=solo ``` ### django后台自定义字段展示，失去排序，添加admin\_order\_field即可 例如： `model.py` ```python suceess_html = '{}' warnign_html = '{}' error_html = '{}' class Dm_AccountModel(models.Model): '''域名解析商''' ns_st = models.CharField(max_length=50, choices=(('使用中', '使用中'), ('备用', '备用'), ('弃用', '弃用')), verbose_name='域商状态') createor = models.ForeignKey( User, verbose_name='创建人', null=True, on_delete=models.SET_NULL) last_editor = models.CharField(max_length=50, null=True, verbose_name='最后编辑者') def color(self): if self.ns_st == '使用中': html = suceess_html elif self.ns_st == '备用': html = warnign_html else: html = error_html return format_html(html, self.ns_st) color.short_description = "域商状态" color.admin_order_field = 'ns_st' # 添加 admin_order_field 实现 admin 后台排序 ns_st_color = color ``` `admin.py` ```python class Dm_AccountModelAdmin(admin.ModelAdmin): list_display = ('ns_st_color',) # 提交时候自动设置当前用户为创建人 def save_model(self, request, obj, form, change): obj.last_editor = request.user.username # 设置最后编辑的人为当前登录用户 if not obj.createor: # 假如没有创建者，就设置当前用户为创建者 obj.createor = request.user obj.save() ``` ### CELERY 4.3.0 任务失败重试机制 #### 存在的现象 在异步调用任务中经常需要调用第三方的api请求，如果一次执行失败，则应该进行重试执行。否则，如果在执行一些连续性的chain链条任务，前面执行失败，那么后续的也就不用执行了。 下面来看看一个发送邮件失败，然后重试执行的示例。 #### CELERY任务的文档结构 #### 错误重试示例 #### 故意将邮件服务的地址配置错误 为了做到错误的演示，我首先将发送邮件的smtp地址写错，如下： 那么稍后执行发送邮件的时候，就一定会报找不到smtp的错误。 #### 编写错误重试的TASK任务 ```python # 定义任务函数 @celery_app.task(bind=True) def send_register_active_email(self,to_email, username, token): '''发送**邮件''' # 组织邮件信息 subject = '欢迎信息' message = '' sender = settings.EMAIL_FROM receiver = [to_email] html_message = '

%s, 欢迎您成为xxx注册会员

请点击下面链接**您的账户
http://127.0.0.1:8000/user/active/%s' % (username, token, token) print("=========== 执行发送邮件 ===============") try: send_mail(subject, message, sender, receiver, html_message=html_message) except Exception as e: """ 邮件发送失败，使用retry进行重试 retry的参数可以有： exc：指定抛出的异常 throw：重试时是否通知worker是重试任务 eta：指定重试的时间／日期 countdown：在多久之后重试（每多少秒重试一次） max_retries：最大重试次数 """ raise self.retry(exc=e, countdown=3, max_retries=5) ``` 该示例任务将会进行调用发送邮件，当发生错误后，间隔3秒则重试执行一次，总共5次。 可以通过`print`的打印信息来确认重试的次数。 #### 启动CELERY任务 windows启动命令： ``` celery -A celery_tasks worker -l info --pool=solo -P eventlet ``` linux启动命令： ``` celery -A celery_tasks worker -l info ``` #### 执行CELERY任务 启动完毕celery之后，那么下面进行交互模式进行测试，执行如下： ``` In [1]: from celery_tasks.tasks import send_register_active_email In [2]: to_email = 'lijw@******.cn' In [3]: token = '123456' In [4]: username = 'lijw' In [5]: send_register_active_email.delay(to_email,username,token) Out[5]: 12345678910 ``` 执行完毕任务后，查看celery的执行日志，如下： ``` [2019-10-21 14:01:09,508: INFO/MainProcess] celery@junwei1 ready. [2019-10-21 14:01:09,509: INFO/MainProcess] pidbox: Connected to redis://127.0.0.1:6379/8. [2019-10-21 14:01:14,353: INFO/MainProcess] Received task: celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] # 任务第一次执行，然后执行失败 [2019-10-21 14:01:14,354: WARNING/MainProcess] =========== 执行发送邮件 =============== [2019-10-21 14:01:15,311: INFO/MainProcess] Received task: celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] ETA:[2019-10-21 06:01:18.21 8857+00:00] [2019-10-21 14:01:15,345: INFO/MainProcess] Task celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] retry: Retry in 3s: gaierror(11001, 'N o address found') # 当执行错误之后，下面则会重试执行5次任务，直到成功，或者失败 [2019-10-21 14:01:18,224: WARNING/MainProcess] =========== 执行发送邮件 =============== [2019-10-21 14:01:18,253: INFO/MainProcess] Received task: celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] ETA:[2019-10-21 06:01:21.22 5853+00:00] [2019-10-21 14:01:18,265: INFO/MainProcess] Task celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] retry: Retry in 3s: gaierror(11001, 'N o address found') [2019-10-21 14:01:21,227: WARNING/MainProcess] =========== 执行发送邮件 =============== [2019-10-21 14:01:21,255: INFO/MainProcess] Received task: celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] ETA:[2019-10-21 06:01:24.22 8790+00:00] [2019-10-21 14:01:21,264: INFO/MainProcess] Task celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] retry: Retry in 3s: gaierror(11001, 'N o address found') [2019-10-21 14:01:24,243: WARNING/MainProcess] =========== 执行发送邮件 =============== [2019-10-21 14:01:24,280: INFO/MainProcess] Received task: celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] ETA:[2019-10-21 06:01:27.24 4729+00:00] [2019-10-21 14:01:24,291: INFO/MainProcess] Task celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] retry: Retry in 3s: gaierror(11001, 'N o address found') [2019-10-21 14:01:27,245: WARNING/MainProcess] =========== 执行发送邮件 =============== [2019-10-21 14:01:27,271: INFO/MainProcess] Received task: celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] ETA:[2019-10-21 06:01:30.24 6720+00:00] [2019-10-21 14:01:27,281: INFO/MainProcess] Task celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] retry: Retry in 3s: gaierror(11001, 'N o address found') [2019-10-21 14:01:30,261: WARNING/MainProcess] =========== 执行发送邮件 =============== [2019-10-21 14:01:30,279: ERROR/MainProcess] Task celery_tasks.tasks.send_register_active_email[7b921776-f6a6-4da0-9c71-b04aac0d139a] raised unexpected: gaierror(11001, 'N o address found') Traceback (most recent call last): .... raise socket.gaierror(socket.EAI_NONAME, 'No address found') socket.gaierror: [Errno 11001] No address found 123456789101112131415161718192021222324252627282930313233343536373839 ``` 可以看到，上面的日志中的打印信息。 第一次执行任务，则发送了一次报错。 随后一直重试执行了5次都报错，说明重试的5次是从第一次执行失败后计算的。 ### Django 渲染模板与 vue 的 {{ }} 冲突解决方法 如果不可避免的在同一个页面里既有 django 渲染又有 vue 渲染的部分，可有 2 种方式解决 #### 方法一： 　　采用 vue 的 [delimiters](https://cn.vuejs.org/v2/api/#delimiters) 分隔符。 ``` new Vue({ delimiters: ["{[", "]}"] // 可自定义符号 }) ``` **方法二：** 建议把 vue 的部分用 包起来。 见文档： ```
{{ text }}
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