python - need - coacción a Unicode: se necesita una cadena o un búfer, se encontró NoneType al renderizar en django admin
coercing to unicode need string or buffer nonetype found (5)
El valor de retorno def __unicode __ debe ser similar al valor de retorno de los modelos relacionados (tablas) para ver correctamente "some_field" en el panel de administración de django. También puedes usar:
def __str__(self):
return self.some_field
Tengo este error desde hace mucho tiempo pero no puedo resolverlo:
Atrapó TypeError mientras se procesa: coacción a Unicode: se necesita una cadena o un búfer, se ha encontrado NoneType
Ocurre en el administrador cuando intento agregar o modificar uno de mis modelos (la pantalla funciona bien)
Este es el modelo:
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'')
¿Alguna idea de qué estoy haciendo mal aquí?
Rastrear:
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
En mi caso, era otra cosa: el objeto que estaba guardando debería tener primero una identificación (por ejemplo, debería llamarse guardar ()) antes de poder establecer cualquier tipo de relación con él.
En primer lugar, compruebe que todo lo que está devolviendo a través de Unicode es un String.
Si no es una cadena, puede cambiarla a una cadena como esta (donde self.id es un número entero)
def __unicode__(self):
return ''%s'' % self.id
después de lo cual, si aún no funciona, reinicie su shell ./manage.py para que los cambios surtan efecto e intente nuevamente. Deberia de funcionar.
Atentamente
Este error puede ocurrir cuando devuelve un objeto en lugar de una cadena en su método __unicode__ . Por ejemplo:
class Author(models.Model):
. . .
name = models.CharField(...)
class Book(models.Model):
. . .
author = models.ForeignKey(Author, ...)
. . .
def __unicode__(self):
return self.author # <<<<<<<< this causes problems
Para evitar este error, puede convertir la instancia de autor a Unicode:
class Book(models.Model):
. . .
def __unicode__(self):
return unicode(self.author) # <<<<<<<< this is OK
Este error se produce cuando tiene un método __unicode__ que devuelve un campo que no se ingresó. Cualquier campo en blanco es None y Python no puede convertir None , por lo que aparece el error.
En su caso, el problema más probable es con el método __unicode__ del modelo PCE , específicamente el campo que está regresando.
Puedes evitar esto devolviendo un valor predeterminado:
def __unicode__(self):
return unicode(self.some_field) or u''''