django 2.2（含 drf）sqlite3 转成 mysql5.7 报错：return instance._state.fields_cache[cache_name] KeyError: 'article'（已解决）
导出导入过程如下：
1. settings DATABASES 使用 sqlite3，执行：
python manage.py dumpdata > data.json
导出 sqlite3 数据。
2. settings DATABASES 使用 mysql, 执行：
python manage.py migrate
生成数据表，然后要删除已经生成数据的表：
3. 进入到MySQL，执行如下的 SQL 语句，删除已经生成数据的表：
use 你的数据库名; delete from auth_permission; delete from django_content_type;
4.settings DATABASES 使用 mysql, 执行：
python manage.py loaddata data.json
django 2.2（含 drf） sqlite3 转成 mysql5.7 ，执行 python manage.py loaddata data.json 时报错如下（有一个 article 模型）:
(joyoo) [root@VM_2_29_centos blog]# python manage.py loaddata data.json
/root/.virtualenvs/joyoo/lib/python3.6/site-packages/daphne/server.py:15: UserWarning: Something has already installed a non-asyncio Twisted reactor. Attempting to uninstall it; you can fix this warning by importing daphne.server early in your codebase or finding the package that imports Twisted and importing it later on.
UserWarning,
System check identified some issues:
Traceback (most recent call last):
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/db/models/fields/related_descriptors.py", line 164, in __get__
rel_obj = self.field.get_cached_value(instance)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/db/models/fields/mixins.py", line 13, in get_cached_value
return instance._state.fields_cache[cache_name]
KeyError: 'article'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "manage.py", line 22, in <module>
execute_from_command_line(sys.argv)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
utility.execute()
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/management/__init__.py", line 375, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/management/base.py", line 323, in run_from_argv
self.execute(*args, **cmd_options)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/management/base.py", line 364, in execute
output = self.handle(*args, **options)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/management/commands/loaddata.py", line 72, in handle
self.loaddata(fixture_labels)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/management/commands/loaddata.py", line 114, in loaddata
self.load_label(fixture_label)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/management/commands/loaddata.py", line 181, in load_label
obj.save(using=self.using)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/core/serializers/base.py", line 223, in save
models.Model.save_base(self.object, using=using, raw=True, **kwargs)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/db/models/base.py", line 790, in save_base
update_fields=update_fields, raw=raw, using=using,
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 175, in send
for receiver in self._live_receivers(sender)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 175, in <listcomp>
for receiver in self._live_receivers(sender)
File "/root/yzq/djangos/blog/blog/blog_signals.py", line 88, in change_comment
comments = instance.article.comment_article_set.filter(is_delete=False).order_by(
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/db/models/fields/related_descriptors.py", line 178, in __get__
rel_obj = self.get_object(instance)
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/db/models/fields/related_descriptors.py", line 145, in get_object
return qs.get(self.field.get_reverse_related_filter(instance))
File "/root/.virtualenvs/joyoo/lib/python3.6/site-packages/django/db/models/query.py", line 408, in get
self.model._meta.object_name
blog.models.DoesNotExist: Problem installing fixture '/root/yzq/djangos/blog/data.json': Article matching query does not exist.
Sentry is attempting to send 1 pending error messages
Waiting up to 10 seconds
Press Ctrl-C to quit
同类问题：
解决办法：
把 app 里面启动信号的地方注释掉导入就能成功，导入完成后再重新打开信号。
1 from django.apps import AppConfig 2 3 4 class BlogConfig(AppConfig): 5 name = 'blog' 6 verbose_name = "B 博客管理" 7 8 # 启用信号 9 #def ready(self): 10 # import blog.blog_signals
内存不足失败的日志（2H2G 服务器导入失败，这个是内存不足，被系统干掉）
(joyoo) [root@VM_2_29_centos blog]# python manage.py loaddata /root/yzq/download/data.json
/root/.virtualenvs/joyoo/lib/python3.6/site-packages/daphne/server.py:15: UserWarning: Something has already installed a non-asyncio Twisted reactor. Attempting to uninstall it; you can fix this warning by importing daphne.server early in your codebase or finding the package that imports Twisted and importing it later on.
UserWarning,
System check identified some issues:
WARNINGS:
finance.FundNet.fund: (fields.W342) Setting unique=True on a ForeignKey has the same effect as using a OneToOneField.
HINT: ForeignKey(unique=True) is usually better served by a OneToOneField.
Building prefix dict from the default dictionary ...
jieba: 2022-04-12 01:35:45,402 /root/.virtualenvs/joyoo/lib/python3.6/site-packages/jieba/__init__.py [line:111] DEBUG Building prefix dict from the default dictionary ...
Loading model from cache /tmp/jieba.cache
jieba: 2022-04-12 01:35:45,406 /root/.virtualenvs/joyoo/lib/python3.6/site-packages/jieba/__init__.py [line:131] DEBUG Loading model from cache /tmp/jieba.cache
Loading model cost 1.018 seconds.
jieba: 2022-04-12 01:35:46,420 /root/.virtualenvs/joyoo/lib/python3.6/site-packages/jieba/__init__.py [line:163] DEBUG Loading model cost 1.018 seconds.
Prefix dict has been built succesfully.
jieba: 2022-04-12 01:35:46,434 /root/.virtualenvs/joyoo/lib/python3.6/site-packages/jieba/__init__.py [line:164] DEBUG Prefix dict has been built succesfully.
Killed
导入成功的日志（在本地台式机导入的）
(joyo) E:\git_stores\blog>python manage.py loaddata data.json
E:\py_envs\joyo\lib\site-packages\daphne\server.py:15: UserWarning: Something has already installed a non-asyncio Twisted reactor. Attempting to uninstall it; you can fix this warning by importing daphne.server early in your codebase or finding the package that imports Twisted and importing it later on.
UserWarning,
System check identified some issues:
WARNINGS:
finance.FundNet.fund: (fields.W342) Setting unique=True on a ForeignKey has the same effect as using a OneToOneField.
HINT: ForeignKey(unique=True) is usually better served by a OneToOneField.
Building prefix dict from the default dictionary ...
jieba: 2023-02-27 23:00:59,499 E:\py_envs\joyo\lib\site-packages\jieba\__init__.py [line:111] DEBUG Building prefix dict from the default dictionary ...
Loading model from cache C:\Users\yinzh\AppData\Local\Temp\jieba.cache
jieba: 2023-02-27 23:00:59,501 E:\py_envs\joyo\lib\site-packages\jieba\__init__.py [line:131] DEBUG Loading model from cache C:\Users\yinzh\AppData\Local\Temp\jieba.cache
Loading model cost 0.836 seconds.
jieba: 2023-02-27 23:01:00,336 E:\py_envs\joyo\lib\site-packages\jieba\__init__.py [line:163] DEBUG Loading model cost 0.836 seconds.
Prefix dict has been built succesfully.
jieba: 2023-02-27 23:01:00,337 E:\py_envs\joyo\lib\site-packages\jieba\__init__.py [line:164] DEBUG Prefix dict has been built succesfully.
Installed 561367 object(s) from 1 fixture(s)
