Python 强制转换为 Unicode：需要字符串或缓冲区，在 django admin 中渲染时发现 NoneType
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时间：2020-08-18 21:56:11 来源:igfitidea点击:
coercing to Unicode: need string or buffer, NoneType found when rendering in django admin
提问by Armance
I have this error since a long time but can't figure it out :
很长一段时间以来我都有这个错误，但无法弄清楚：
Caught TypeError while rendering: coercing to Unicode: need string or buffer, NoneType found
渲染时捕获 TypeError：强制转换为 Unicode：需要字符串或缓冲区，找到 NoneType
It happens in admin when I try to add or modify on one of my models (display works fine)
当我尝试在我的模型之一上添加或修改时，它发生在管理员中（显示工作正常）
This is the model:
这是模型：
class PS(models.Model):
id_ps = models.IntegerField(null=True)
client = models.ForeignKey(Client, null=True, blank=True)
nom_du_site = models.CharField(max_length=250)
rue_livraison = models.TextField(null=True)
complement_adresse = models.TextField(null=True)
code_postal_livraison = models.CharField(max_length=50, null=True)
ville_livraison = models.CharField(max_length=200, null=True)
pays_livraison = models.CharField(max_length=200, null=True)
distributeur = models.CharField(max_length=50, null=True)
tarif = models.CharField(max_length=250, null=True)
type_tarif = models.CharField(max_length=50, null=True)
type_installation = models.CharField(max_length=50, null=True)
def __unicode__(self):
return self.nom_du_site
@property
def pce(self):
try:
return PCE.objects.filter(ps=self)[0]
except IndexError:
return
#
def get_pce(self):
from pce.models import PCE
return PCE.objects.filter(ps=self).exclude(frequence='6M')
#
def get_pce_6m(self):
from pce.models import PCE
return PCE.objects.filter(ps=self,frequence='6M')
Any idea what am i doing wrong here?
知道我在这里做错了什么吗？
Traceback:
追溯：
Environment:
Request Method: GET
Request URL: http://127.0.0.1:8026/admin/ps/ps/add/
Django Version: 1.2.5
Python Version: 2.7.2
Installed Applications:
['django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.messages',
'django.contrib.admin',
'easy_thumbnails',
'django_extensions',
'contentadmin',
'south',
'sentry',
'sentry.client',
'indexer',
'file_uploader',
'paging',
'pagination',
'consommation',
'ps',
'pce',
'profil',
'analytics',
'document']
Installed Middleware:
('annoying.middlewares.StaticServe',
'django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'pagination.middleware.PaginationMiddleware')
Template error:
In template /usr/local/lib/python2.7/dist-packages/django/contrib/admin/templates/admin/includes/fieldset.html, error at line 19
Caught TypeError while rendering: coercing to Unicode: need string or buffer, NoneType found
9 : {% for field in line %}
10 : <div{% if not line.fields|length_is:'1' %} class="field-box{% if not field.is_readonly and field.errors %} errors{% endif %}"{% endif %}>
11 : {% if not line.fields|length_is:'1' and not field.is_readonly %}{{ field.errors }}{% endif %}
12 : {% if field.is_checkbox %}
13 : {{ field.field }}{{ field.label_tag }}
14 : {% else %}
15 : {{ field.label_tag }}
16 : {% if field.is_readonly %}
17 : <p>{{ field.contents }}</p>
18 : {% else %}
19 : {{ field.field }}
20 : {% endif %}
21 : {% endif %}
22 : {% if field.field.field.help_text %}
23 : <p class="help">{{ field.field.field.help_text|safe }}</p>
24 : {% endif %}
25 : </div>
26 : {% endfor %}
27 : </div>
28 : {% endfor %}
29 : </fieldset>
Traceback:
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response
100. response = callback(request, *callback_args, **callback_kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py" in wrapper
288. return self.admin_site.admin_view(view)(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapped_view
76. response = view_func(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/views/decorators/cache.py" in _wrapped_view_func
78. response = view_func(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/sites.py" in inner
190. return view(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapper
21. return decorator(bound_func)(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapped_view
76. response = view_func(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in bound_func
17. return func(self, *args2, **kwargs2)
File "/usr/local/lib/python2.7/dist-packages/django/db/transaction.py" in _commit_on_success
299. res = func(*args, **kw)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py" in add_view
909. return self.render_change_form(request, context, form_url=form_url, add=True)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py" in render_change_form
692. ], context, context_instance=context_instance)
File "/usr/local/lib/python2.7/dist-packages/django/shortcuts/__init__.py" in render_to_response
20. return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/template/loader.py" in render_to_string
186. return t.render(context_instance)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
173. return self._render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in _render
167. return self.nodelist.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
796. bits.append(self.render_node(node, context))
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render_node
72. result = node.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/loader_tags.py" in render
125. return compiled_parent._render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in _render
167. return self.nodelist.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
796. bits.append(self.render_node(node, context))
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render_node
72. result = node.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/loader_tags.py" in render
125. return compiled_parent._render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in _render
167. return self.nodelist.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
796. bits.append(self.render_node(node, context))
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render_node
72. result = node.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/loader_tags.py" in render
62. result = block.nodelist.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
796. bits.append(self.render_node(node, context))
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render_node
72. result = node.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/defaulttags.py" in render
174. nodelist.append(node.render(context))
File "/usr/local/lib/python2.7/dist-packages/django/template/loader_tags.py" in render
139. return self.template.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
173. return self._render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in _render
167. return self.nodelist.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
796. bits.append(self.render_node(node, context))
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render_node
72. result = node.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/defaulttags.py" in render
174. nodelist.append(node.render(context))
File "/usr/local/lib/python2.7/dist-packages/django/template/defaulttags.py" in render
174. nodelist.append(node.render(context))
File "/usr/local/lib/python2.7/dist-packages/django/template/defaulttags.py" in render
260. return self.nodelist_false.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
796. bits.append(self.render_node(node, context))
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render_node
72. result = node.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/defaulttags.py" in render
260. return self.nodelist_false.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/__init__.py" in render
796. bits.append(self.render_node(node, context))
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render_node
72. result = node.render(context)
File "/usr/local/lib/python2.7/dist-packages/django/template/debug.py" in render
91. output = force_unicode(output)
File "/usr/local/lib/python2.7/dist-packages/django/utils/encoding.py" in force_unicode
66. s = unicode(s)
File "/usr/local/lib/python2.7/dist-packages/django/forms/forms.py" in __unicode__
408. return self.as_widget()
File "/usr/local/lib/python2.7/dist-packages/django/forms/forms.py" in as_widget
450. return widget.render(name, data, attrs=attrs)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/widgets.py" in render
247. output = [self.widget.render(name, value, *args, **kwargs)]
File "/usr/local/lib/python2.7/dist-packages/django/forms/widgets.py" in render
447. options = self.render_options(choices, [value])
File "/usr/local/lib/python2.7/dist-packages/django/forms/widgets.py" in render_options
464. for option_value, option_label in chain(self.choices, choices):
File "/usr/local/lib/python2.7/dist-packages/django/forms/models.py" in __iter__
898. yield self.choice(obj)
File "/usr/local/lib/python2.7/dist-packages/django/forms/models.py" in choice
904. return (self.field.prepare_value(obj), self.field.label_from_instance(obj))
File "/usr/local/lib/python2.7/dist-packages/django/forms/models.py" in label_from_instance
955. return smart_unicode(obj)
File "/usr/local/lib/python2.7/dist-packages/django/utils/encoding.py" in smart_unicode
39. return force_unicode(s, encoding, strings_only, errors)
File "/usr/local/lib/python2.7/dist-packages/django/utils/encoding.py" in force_unicode
66. s = unicode(s)
Exception Type: TemplateSyntaxError at /admin/ps/ps/add/
Exception Value: Caught TypeError while rendering: coercing to Unicode: need string or buffer, NoneType found
采纳答案by Burhan Khalid
This error happens when you have a __unicode__method that is a returning a field that is not entered. Any blank field is Noneand Python cannot convert None, so you get the error.
当您的__unicode__方法返回未输入的字段时，会发生此错误。任何空白字段是None并且 Python 无法转换None，因此您会收到错误消息。
In your case, the problem most likely is with the PCEmodel's __unicode__method, specifically the field its returning.
在您的情况下，问题很可能出在PCE模型的__unicode__方法上，特别是它返回的字段。
You can prevent this by returning a default value:
您可以通过返回默认值来防止这种情况：
def __unicode__(self):
return self.some_field or u'None'
回答by laycat
First, check that whatever you are returning via unicodeis a String.
首先，检查您通过unicode返回的任何内容是否为字符串。
If it is not a string you can change it to a string like this (where self.id is an integer)
如果它不是字符串，您可以将其更改为这样的字符串（其中 self.id 是一个整数）
def __unicode__(self):
return '%s' % self.id
following which, if it still doesn't work, restart your ./manage.py shell for the changes to take effect and try again. It should work.
接下来，如果它仍然不起作用，请重新启动 ./manage.py shell 以使更改生效并重试。它应该工作。
Best Regards
此致
回答by Boris Chervenkov
This error might occur when you return an object instead of a string in your __unicode__method. For example:
当您在__unicode__方法中返回对象而不是字符串时，可能会发生此错误。例如：
class Author(models.Model):
. . .
name = models.CharField(...)
class Book(models.Model):
. . .
author = models.ForeignKey(Author, ...)
. . .
def __unicode__(self):
return self.author # <<<<<<<< this causes problems
To avoid this error you can cast the author instance to unicode:
为避免此错误，您可以将作者实例转换为 unicode：
class Book(models.Model):
. . .
def __unicode__(self):
return unicode(self.author) # <<<<<<<< this is OK
回答by Patrick Bassut
In my case it was something else: the object I was saving should first have an id(e.g. save() should be called) before I could set any kind of relationship with it.
在我的情况下，它是别的东西：我要保存的对象应该首先有一个 id（例如，应该调用 save()），然后才能与它设置任何类型的关系。
回答by Ronny Morán
The return value def __unicode __ should be similar to the return value of the related models (tables) for correct viewing of "some_field" in django admin panel. You can also use:
返回值 def __unicode __ 应该类似于相关模型（表）的返回值，以便在 django 管理面板中正确查看“some_field”。您还可以使用：
def __str__(self):
return self.some_field
回答by Ank_247shbm
Replace the earlier function with the provided one. The simplest solution is:
用提供的函数替换之前的函数。最简单的解决方案是：
def __unicode__(self):
return unicode(self.nom_du_site)
