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社区首页 >问答首页 >Django:在删除前更改记录的值

问Django:在删除前更改记录的值
EN

Stack Overflow用户
提问于 2018-10-09 02:53:50
回答 1查看 28关注 0票数 0

在删除记录之前，我正在尝试更改其中一个字段：

代码语言：javascript
复制
query_item.txId = txId
try:
    query_item.delete()
except Exception as e:
        print(str(e))

关键是上面写的代码会导致异常：

当前事务中发生错误。您不能执行查询，直到‘原子’块的末尾。

我试着玩过

代码语言：javascript
复制
with transaction.atomic():

语句，但它根本没有改变任何事情。

此外，还包括以下组合：

代码语言：javascript
复制
query_item.txId = txId
query_item.save()
try:
    query_item.delete()
except Exception as e:
        print(str(e))

仍然会导致相同的错误

@编辑

在整个项目中，只有一个信号指向属于query_item模型的记录：

代码语言：javascript
复制
pre_delete.connect(create_receipts, sender=itemToPurchase)

@edit2

这肯定是pre_delete信号出了问题

我只是移除了它，测试进行得很顺利。

无论如何，每当我使用上面写的signal & delete每个try-except语句时，我都会收到以下错误日志：

代码语言：javascript
复制
Traceback (most recent call last):
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/base.py", line 126, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/base.py", line 124, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/contextlib.py", line 74, in inner
    return func(*args, **kwds)
  File "User/env/lib/python3.7/site-packages/django/views/generic/base.py", line 68, in view
    return self.dispatch(request, *args, **kwargs)
  File "User/env/lib/python3.7/site-packages/django/views/generic/base.py", line 88, in dispatch
    return handler(request, *args, **kwargs)
  File "User/profilespaidbybtc/payment_realizer/views.py", line 240, in post
    query_item.delete()
  File "User/env/lib/python3.7/site-packages/django/db/models/base.py", line 880, in delete
    return collector.delete()
  File "User/env/lib/python3.7/site-packages/django/db/models/deletion.py", line 277, in delete
    sender=model, instance=obj, using=self.using
  File "User/env/lib/python3.7/site-packages/django/dispatch/dispatcher.py", line 175, in send
    for receiver in self._live_receivers(sender)
  File "User/env/lib/python3.7/site-packages/django/dispatch/dispatcher.py", line 175, in <listcomp>
    for receiver in self._live_receivers(sender)
  File "User/profilespaidbybtc/receipt/models.py", line 186, in create_receipts
    'token': hash_generator_token.make_token(instance_receiptModel)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 61, in render_to_string
    template = get_template(template_name, using=using)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 15, in get_template
    return engine.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/backends/django.py", line 34, in get_template
    return Template(self.engine.get_template(template_name), self)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 144, in get_template
    template, origin = self.find_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 124, in find_template
    for loader in self.template_loaders:
  File "User/env/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 98, in template_loaders
    return self.get_template_loaders(self.loaders)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 103, in get_template_loaders
    loader = self.find_template_loader(template_loader)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 116, in find_template_loader
    loader_class = import_string(loader)
  File "User/env/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "User/env/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'app_namespace'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "User/env/lib/python3.7/site-packages/django/utils/deprecation.py", line 91, in __call__
    response = response or self.get_response(request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 36, in inner
    response = response_for_exception(request, exc)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 90, in response_for_exception
    response = handle_uncaught_exception(request, get_resolver(get_urlconf()), sys.exc_info())
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 129, in handle_uncaught_exception
    return callback(request, **param_dict)
  File "User/env/lib/python3.7/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "User/env/lib/python3.7/site-packages/django/views/defaults.py", line 69, in server_error
    template = loader.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 15, in get_template
    return engine.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/backends/django.py", line 34, in get_template
    return Template(self.engine.get_template(template_name), self)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 144, in get_template
    template, origin = self.find_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 124, in find_template
    for loader in self.template_loaders:
  File "User/env/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 98, in template_loaders
    return self.get_template_loaders(self.loaders)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 103, in get_template_loaders
    loader = self.find_template_loader(template_loader)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 116, in find_template_loader
    loader_class = import_string(loader)
  File "User/env/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "User/env/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'app_namespace'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "User/env/lib/python3.7/site-packages/django/utils/deprecation.py", line 91, in __call__
    response = response or self.get_response(request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 36, in inner
    response = response_for_exception(request, exc)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 90, in response_for_exception
    response = handle_uncaught_exception(request, get_resolver(get_urlconf()), sys.exc_info())
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 129, in handle_uncaught_exception
    return callback(request, **param_dict)
  File "User/env/lib/python3.7/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "User/env/lib/python3.7/site-packages/django/views/defaults.py", line 69, in server_error
    template = loader.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 15, in get_template
    return engine.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/backends/django.py", line 34, in get_template
    return Template(self.engine.get_template(template_name), self)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 144, in get_template
    template, origin = self.find_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 124, in find_template
    for loader in self.template_loaders:
  File "User/env/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 98, in template_loaders
    return self.get_template_loaders(self.loaders)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 103, in get_template_loaders
    loader = self.find_template_loader(template_loader)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 116, in find_template_loader
    loader_class = import_string(loader)
  File "User/env/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "User/env/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'app_namespace'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "User/env/lib/python3.7/site-packages/django/utils/deprecation.py", line 91, in __call__
    response = response or self.get_response(request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 36, in inner
    response = response_for_exception(request, exc)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 90, in response_for_exception
    response = handle_uncaught_exception(request, get_resolver(get_urlconf()), sys.exc_info())
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 129, in handle_uncaught_exception
    return callback(request, **param_dict)
  File "User/env/lib/python3.7/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "User/env/lib/python3.7/site-packages/django/views/defaults.py", line 69, in server_error
    template = loader.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 15, in get_template
    return engine.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/backends/django.py", line 34, in get_template
    return Template(self.engine.get_template(template_name), self)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 144, in get_template
    template, origin = self.find_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 124, in find_template
    for loader in self.template_loaders:
  File "User/env/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 98, in template_loaders
    return self.get_template_loaders(self.loaders)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 103, in get_template_loaders
    loader = self.find_template_loader(template_loader)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 116, in find_template_loader
    loader_class = import_string(loader)
  File "User/env/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "User/env/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'app_namespace'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "User/env/lib/python3.7/site-packages/django/utils/deprecation.py", line 91, in __call__
    response = response or self.get_response(request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 36, in inner
    response = response_for_exception(request, exc)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 90, in response_for_exception
    response = handle_uncaught_exception(request, get_resolver(get_urlconf()), sys.exc_info())
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 129, in handle_uncaught_exception
    return callback(request, **param_dict)
  File "User/env/lib/python3.7/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "User/env/lib/python3.7/site-packages/django/views/defaults.py", line 69, in server_error
    template = loader.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 15, in get_template
    return engine.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/backends/django.py", line 34, in get_template
    return Template(self.engine.get_template(template_name), self)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 144, in get_template
    template, origin = self.find_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 124, in find_template
    for loader in self.template_loaders:
  File "User/env/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 98, in template_loaders
    return self.get_template_loaders(self.loaders)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 103, in get_template_loaders
    loader = self.find_template_loader(template_loader)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 116, in find_template_loader
    loader_class = import_string(loader)
  File "User/env/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "User/env/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'app_namespace'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "User/env/lib/python3.7/site-packages/django/utils/deprecation.py", line 91, in __call__
    response = response or self.get_response(request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 36, in inner
    response = response_for_exception(request, exc)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 90, in response_for_exception
    response = handle_uncaught_exception(request, get_resolver(get_urlconf()), sys.exc_info())
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 129, in handle_uncaught_exception
    return callback(request, **param_dict)
  File "User/env/lib/python3.7/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "User/env/lib/python3.7/site-packages/django/views/defaults.py", line 69, in server_error
    template = loader.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 15, in get_template
    return engine.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/backends/django.py", line 34, in get_template
    return Template(self.engine.get_template(template_name), self)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 144, in get_template
    template, origin = self.find_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 124, in find_template
    for loader in self.template_loaders:
  File "User/env/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 98, in template_loaders
    return self.get_template_loaders(self.loaders)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 103, in get_template_loaders
    loader = self.find_template_loader(template_loader)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 116, in find_template_loader
    loader_class = import_string(loader)
  File "User/env/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "User/env/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'app_namespace'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "User/env/lib/python3.7/site-packages/django/utils/deprecation.py", line 91, in __call__
    response = response or self.get_response(request)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 36, in inner
    response = response_for_exception(request, exc)
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 90, in response_for_exception
    response = handle_uncaught_exception(request, get_resolver(get_urlconf()), sys.exc_info())
  File "User/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 129, in handle_uncaught_exception
    return callback(request, **param_dict)
  File "User/env/lib/python3.7/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "User/env/lib/python3.7/site-packages/django/views/defaults.py", line 69, in server_error
    template = loader.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/loader.py", line 15, in get_template
    return engine.get_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/backends/django.py", line 34, in get_template
    return Template(self.engine.get_template(template_name), self)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 144, in get_template
    template, origin = self.find_template(template_name)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 124, in find_template
    for loader in self.template_loaders:
  File "User/env/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 98, in template_loaders
    return self.get_template_loaders(self.loaders)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 103, in get_template_loaders
    loader = self.find_template_loader(template_loader)
  File "User/env/lib/python3.7/site-packages/django/template/engine.py", line 116, in find_template_loader
    loader_class = import_string(loader)
  File "User/env/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "User/env/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'app_namespace'

During handling of the above exception, another exception occurred:
django
database
record
EN

回答 1

Stack Overflow用户

回答已采纳

发布于 2018-10-09 03:26:40

我不能给你一个解决方案。但是回溯显示信号处理函数中有一个错误。特别是这一行：

代码语言：javascript
复制
File "User/profilespaidbybtc/receipt/models.py", line 186, in create_receipts
  'token': hash_generator_token.make_token(instance_receiptModel)

Django在一个原子数据库事务中同时处理pre_delete、post_delete和删除。因此，如果这些步骤中的任何一个步骤中存在错误，都不会向数据库提交任何更改。这可以防止您的数据因为您删除了某些内容而最终处于不确定状态，但bug阻止了其他清理或其他操作。

要修复该错误，您应该查找导致此导入错误的一些代码。

代码语言：javascript
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ModuleNotFoundError: No module named 'app_namespace'

这与Django的模板加载框架有关。我认为在create_receipts信号处理函数中发生了一些模板呈现，并且django无法加载模块app_namespace来查找模板文件。

app_namespace看起来像一个占位符名称。如果您在代码库中搜索此变量名称，您可能会找到错误的来源。这可能是错误的模板名称和settings.py中django模板加载配置中不存在的模块名称或目录的组合。

票数 1
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/52708451

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