DJango TypeError - JSFiles 对象不可逆
DJango TypeError - JSFiles object is not reversible
我试图在我的 DJango 2.0.2 版中包含 this datepicket widget，但它引发了错误
Request Method: GET
Request URL: http://127.0.0.1:8000/xuser/1/edit
Django Version: 2.0.2
Exception Type: TypeError
Exception Value: 'JSFiles' object is not reversible
Exception Location: D:\DevTools\Python\lib\site-packages\django\forms\widgets.py in merge, line 114
Python Executable: D:\DevTools\Python\python.exe
Python Version: 3.6.3
我已经在以下线程中寻找类似的错误
但这些只是关于 urlpatterns 的 拼写错误 ，甚至没有透露 python 中可逆的实际含义。 google search 关于可逆对象不会产生比上述线程更多的东西。所以，我的问题是，
- 可逆对象是什么意思？
- 我该如何解决这个问题？
Traceback:
Environment:
Request Method: GET
Request URL: http://127.0.0.1:8000/xuser/1/edit
Django Version: 2.0.2
Python Version: 3.6.3
Installed Applications:
['bootstrap3',
'bootstrap_datepicker',
'core.apps.CoreConfig',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles']
Installed 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']
Template error:
In template D:\Python\dj_abstractbaseuser2\core\templates\core\edit.html, error at line 8
'JSFiles' object is not reversible
1 : {# Load the tag library #}
2 : {% load bootstrap3 %}
3 :
4 : {# Load CSS and JavaScript #}
5 : {% bootstrap_css %}
6 : {% bootstrap_javascript %}
7 : {% block extrahead %}
8 : {{ form.media }}
9 : {% endblock %}
10 :
11 : {# Display django.contrib.messages as Bootstrap alerts #}
12 : {% bootstrap_messages %}
13 : <form method="post">
14 : {% csrf_token %}
15 : {% bootstrap_field form.first_name %}
16 : {% bootstrap_field form.last_name %}
17 : {% bootstrap_field form.date_of_birth %}
18 : {% buttons %}
Traceback:
File "D:\DevTools\Python\lib\site-packages\django\forms\forms.py" in __getitem__
157. field = self.fields[name]
During handling of the above exception ('media'), another exception occurred:
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in _resolve_lookup
835. current = current[bit]
File "D:\DevTools\Python\lib\site-packages\django\forms\forms.py" in __getitem__
163. ', '.join(sorted(f for f in self.fields)),
During handling of the above exception ("Key 'media' not found in 'UserEditForm'. Choices are: date_of_birth, first_name, last_name."), another exception occurred:
File "D:\DevTools\Python\lib\site-packages\django\core\handlers\exception.py" in inner
35. response = get_response(request)
File "D:\DevTools\Python\lib\site-packages\django\core\handlers\base.py" in _get_response
158. response = self.process_exception_by_middleware(e, request)
File "D:\DevTools\Python\lib\site-packages\django\core\handlers\base.py" in _get_response
156. response = response.render()
File "D:\DevTools\Python\lib\site-packages\django\template\response.py" in render
106. self.content = self.rendered_content
File "D:\DevTools\Python\lib\site-packages\django\template\response.py" in rendered_content
83. content = template.render(context, self._request)
File "D:\DevTools\Python\lib\site-packages\django\template\backends\django.py" in render
61. return self.template.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
175. return self._render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in _render
167. return self.nodelist.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
943. bit = node.render_annotated(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render_annotated
910. return self.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\loader_tags.py" in render
58. result = self.nodelist.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
943. bit = node.render_annotated(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render_annotated
910. return self.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
993. output = self.filter_expression.resolve(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in resolve
676. obj = self.var.resolve(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in resolve
802. value = self._resolve_lookup(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in _resolve_lookup
843. current = getattr(current, bit)
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
148. base = sup_cls.media
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
148. base = sup_cls.media
File "D:\DevTools\Python\lib\site-packages\django\forms\forms.py" in media
460. media = media + field.widget.media
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
148. base = sup_cls.media
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
163. return m + Media(definition)
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in __add__
135. combined._js = self.merge(self._js, other._js)
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in merge
114. for path in reversed(list_2):
Exception Type: TypeError at /xuser/1/edit
Exception Value: 'JSFiles' object is not reversible
错误是由this issue submitted to the widget's Github page, and has not yet been solved. So I switched to django-bootstrap-datepicker-plus引起的，它在我的DJango 2.0.2版本中运行得很好。但问题仍然需要回答。
What is a reversible object? Why we get this Error?
错误是由 python built-in 函数 reversed 引发的，该函数将序列作为唯一参数并反转序列。
reversed() Parameters
seq - sequence that should be reversed.
- Could be an object that supports sequence protocol (
__len__() and __getitem__() methods) as tuple, string, list or range
- Could be an object that has implemented
__reversed__()
因此所有序列（例如列表、元组）都是可逆的。但是要使对象可逆，我们需要实现一个名为 __reversed__ 的方法，或者同时实现 __len__() 和 __getitem__() 方法。如果我们将对象传递给不满足上述任何条件的 reversed() 函数，它将引发异常 TypeError - object is not reversible.
DJango 2.0 将此 reversed() 函数用于任何小部件添加的资产。由于上述小部件中使用的 JSFiles 对象未实现可逆标准，因此引发了错误。
我试图在我的 DJango 2.0.2 版中包含 this datepicket widget，但它引发了错误
Request Method: GET
Request URL: http://127.0.0.1:8000/xuser/1/edit
Django Version: 2.0.2
Exception Type: TypeError
Exception Value: 'JSFiles' object is not reversible
Exception Location: D:\DevTools\Python\lib\site-packages\django\forms\widgets.py in merge, line 114
Python Executable: D:\DevTools\Python\python.exe
Python Version: 3.6.3
我已经在以下线程中寻找类似的错误
但这些只是关于 urlpatterns 的 拼写错误 ，甚至没有透露 python 中可逆的实际含义。 google search 关于可逆对象不会产生比上述线程更多的东西。所以，我的问题是，
- 可逆对象是什么意思？
- 我该如何解决这个问题？
Traceback:
Environment:
Request Method: GET
Request URL: http://127.0.0.1:8000/xuser/1/edit
Django Version: 2.0.2
Python Version: 3.6.3
Installed Applications:
['bootstrap3',
'bootstrap_datepicker',
'core.apps.CoreConfig',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles']
Installed 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']
Template error:
In template D:\Python\dj_abstractbaseuser2\core\templates\core\edit.html, error at line 8
'JSFiles' object is not reversible
1 : {# Load the tag library #}
2 : {% load bootstrap3 %}
3 :
4 : {# Load CSS and JavaScript #}
5 : {% bootstrap_css %}
6 : {% bootstrap_javascript %}
7 : {% block extrahead %}
8 : {{ form.media }}
9 : {% endblock %}
10 :
11 : {# Display django.contrib.messages as Bootstrap alerts #}
12 : {% bootstrap_messages %}
13 : <form method="post">
14 : {% csrf_token %}
15 : {% bootstrap_field form.first_name %}
16 : {% bootstrap_field form.last_name %}
17 : {% bootstrap_field form.date_of_birth %}
18 : {% buttons %}
Traceback:
File "D:\DevTools\Python\lib\site-packages\django\forms\forms.py" in __getitem__
157. field = self.fields[name]
During handling of the above exception ('media'), another exception occurred:
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in _resolve_lookup
835. current = current[bit]
File "D:\DevTools\Python\lib\site-packages\django\forms\forms.py" in __getitem__
163. ', '.join(sorted(f for f in self.fields)),
During handling of the above exception ("Key 'media' not found in 'UserEditForm'. Choices are: date_of_birth, first_name, last_name."), another exception occurred:
File "D:\DevTools\Python\lib\site-packages\django\core\handlers\exception.py" in inner
35. response = get_response(request)
File "D:\DevTools\Python\lib\site-packages\django\core\handlers\base.py" in _get_response
158. response = self.process_exception_by_middleware(e, request)
File "D:\DevTools\Python\lib\site-packages\django\core\handlers\base.py" in _get_response
156. response = response.render()
File "D:\DevTools\Python\lib\site-packages\django\template\response.py" in render
106. self.content = self.rendered_content
File "D:\DevTools\Python\lib\site-packages\django\template\response.py" in rendered_content
83. content = template.render(context, self._request)
File "D:\DevTools\Python\lib\site-packages\django\template\backends\django.py" in render
61. return self.template.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
175. return self._render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in _render
167. return self.nodelist.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
943. bit = node.render_annotated(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render_annotated
910. return self.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\loader_tags.py" in render
58. result = self.nodelist.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
943. bit = node.render_annotated(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render_annotated
910. return self.render(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in render
993. output = self.filter_expression.resolve(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in resolve
676. obj = self.var.resolve(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in resolve
802. value = self._resolve_lookup(context)
File "D:\DevTools\Python\lib\site-packages\django\template\base.py" in _resolve_lookup
843. current = getattr(current, bit)
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
148. base = sup_cls.media
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
148. base = sup_cls.media
File "D:\DevTools\Python\lib\site-packages\django\forms\forms.py" in media
460. media = media + field.widget.media
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
148. base = sup_cls.media
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in _media
163. return m + Media(definition)
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in __add__
135. combined._js = self.merge(self._js, other._js)
File "D:\DevTools\Python\lib\site-packages\django\forms\widgets.py" in merge
114. for path in reversed(list_2):
Exception Type: TypeError at /xuser/1/edit
Exception Value: 'JSFiles' object is not reversible
错误是由this issue submitted to the widget's Github page, and has not yet been solved. So I switched to django-bootstrap-datepicker-plus引起的，它在我的DJango 2.0.2版本中运行得很好。但问题仍然需要回答。
What is a reversible object? Why we get this Error?
错误是由 python built-in 函数 reversed 引发的，该函数将序列作为唯一参数并反转序列。
reversed() Parameters
seq - sequence that should be reversed.
- Could be an object that supports sequence protocol (
__len__()and__getitem__()methods) as tuple, string, list or range- Could be an object that has implemented
__reversed__()
因此所有序列（例如列表、元组）都是可逆的。但是要使对象可逆，我们需要实现一个名为 __reversed__ 的方法，或者同时实现 __len__() 和 __getitem__() 方法。如果我们将对象传递给不满足上述任何条件的 reversed() 函数，它将引发异常 TypeError - object is not reversible.
DJango 2.0 将此 reversed() 函数用于任何小部件添加的资产。由于上述小部件中使用的 JSFiles 对象未实现可逆标准，因此引发了错误。