对不起，如果以前已经有人问过这个问题，但是我还没有找到解决方法，请仔细阅读前面的问题。
我正在尝试在我的网站/应用程序上使用django-booking（https://github.com/bitlabstudio/django-booking/tree/master/booking），现在我可以作为客户端进行预订并保存预订了，但是在管理端，如果我单击预订，我会和错误
> TypeError at /admin/booking/booking/
>
> __str__ returned non-string (type NoneType)
>
> Request Method: GET Request URL:
> http://127.0.0.1:8000/admin/booking/booking/ Django Version: 2.0.8
> Exception Type: TypeError Exception Value:
>
> __str__ returned non-string (type NoneType)
>
> Exception Location: C:\Program
> Files\Python37\lib\site-packages\django\contrib\admin\templatetags\admin_list.py
> in items_for_result, line 235 Python Executable: C:\Program
> Files\Python37\python.exe Python Version: 3.7.0 Python Path:
>
> ['C:\\Users\\Agustin Landivar\\Desktop\\Marie\\drLandivar',
> 'C:\\Program Files\\Python37\\python37.zip', 'C:\\Program
> Files\\Python37\\DLLs', 'C:\\Program Files\\Python37\\lib',
> 'C:\\Program Files\\Python37', 'C:\\Program
> Files\\Python37\\lib\\site-packages']
>
> Server time: Tue, 21 Aug 2018 15:20:18 +0000 Error during template
> rendering
>
> In template C:\Program
> Files\Python37\lib\site-packages\django\contrib\admin\templates\admin\base.html,
> error at line 70
我该如何解决这个问题，以便能够在不出现此错误的情况下查看管理员中的所有预订，我通常看到此错误是由于str引起的，但是它也说该错误在django / contrib文件夹中我从没碰过：/
admin.py
"""Admin classes for the booking app."""
from django.contrib import admin
from hvad.admin import TranslatableAdmin
from . import models
from booking.models import Booking
class BookingAdmin(admin.ModelAdmin):
list_display = [
'creation_date', 'booking_status', 'booking_id', 'user', 'email',
'session', 'date_from', 'date_until',
]
class BookingItemAdmin(admin.ModelAdmin):
list_display = ['booking', 'booked_item', 'quantity', 'persons']
admin.site.register(models.Booking, BookingAdmin)
admin.site.register(models.BookingError)
admin.site.register(models.BookingItem, BookingItemAdmin)
admin.site.register(models.BookingStatus, TranslatableAdmin)
admin.site.register(models.ExtraPersonInfo)
forms.py
"""Forms for the ``booking`` app."""
from django import forms
from django.conf import settings
from django.contrib.auth import authenticate
from django.contrib.auth.forms import AuthenticationForm
from django.utils.translation import ugettext_lazy as _
from .models import Booking, BookingStatus
class BookingForm(forms.ModelForm):
def __init__(self, session=None, user=None, *args, **kwargs):
self.user = user
self.session = session
super(BookingForm, self).__init__(*args, **kwargs)
# fields that should remain blank / not required
keep_blank = [
'phone', 'notes', 'street2', 'title', 'user', 'session',
'date_from', 'date_until', 'special_request', 'time_period',
'time_unit', 'email', 'currency', 'total']
# set all fields except the keep_blank ones to be required, since they
# need to be blank=True on the model itself to allow creating Booking
# instances without data
for name, field in self.fields.items():
if name not in keep_blank:
self.fields[name].required = True
def save(self, *args, **kwargs):
if not self.instance.pk:
self.instance.user = self.user
self.instance.session = self.session
status_object, created = BookingStatus.objects.get_or_create(
slug=getattr(settings, 'BOOKING_STATUS_CREATED', 'pending'))
self.instance.booking_status = status_object
return super(BookingForm, self).save(*args, **kwargs)
class Meta:
model = Booking
fields = ('gender', 'title', 'forename', 'surname', 'nationality',
'street1', 'street2', 'city', 'zip_code', 'country', 'phone',
'special_request', 'date_from', 'date_until')
class BookingIDAuthenticationForm(AuthenticationForm):
def __init__(self, *args, **kwargs):
super(BookingIDAuthenticationForm, self).__init__(*args, **kwargs)
self.fields['username'] = forms.CharField(
label=_("Email"), max_length=256)
self.fields['password'] = forms.CharField(
label=_("Booking ID"), max_length=100)
def clean_username(self):
"""Prevent case-sensitive erros in email/username."""
return self.cleaned_data['username'].lower()
def clean(self):
email = self.cleaned_data.get('username')
booking_id = self.cleaned_data.get('password')
if email and booking_id:
self.user_cache = authenticate(username=email,
password=booking_id)
if self.user_cache is None:
raise forms.ValidationError(_(
'We cannot find a valid booking ID for this email'
' address.')
)
elif not self.user_cache.is_active:
raise forms.ValidationError(self.error_messages['inactive'])
self.check_for_test_cookie()
return self.cleaned_data
models.py
"""Models for the ``booking`` app."""
from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.utils.encoding import python_2_unicode_compatible
from django.utils.translation import ugettext_lazy as _
from django_libs.models_mixins import TranslationModelMixin
from django_countries.fields import CountryField
from hvad.models import TranslatableModel, TranslatedFields
from drLandivar import settings
class BookingStatus(TranslationModelMixin, TranslatableModel):
"""
Master data containing all booking status.
For translatable fields check ``BookingStatusTranslation``.
:slug: A unique slug identifier.
translated:
:name: The displayable name for the status.
"""
slug = models.SlugField(
verbose_name=_('Slug'),
)
translations = TranslatedFields(
name=models.CharField(
verbose_name=_('Name'),
max_length=128,
)
)
@python_2_unicode_compatible
class Booking(models.Model):
user = models.ForeignKey(
'users.CustomUser',
verbose_name=_('User'),
related_name='bookings',
blank=True, null=True,
on_delete=models.CASCADE,
)
session = models.ForeignKey(
'sessions.Session',
verbose_name=_('Session'),
blank=True, null=True,
on_delete=models.CASCADE,
)
gender = models.CharField(
max_length=10,
verbose_name=_('Gender'),
choices=(
('mrs', _('Mrs')),
('mr', _('Mr')),
),
blank=True,
)
title = models.CharField(
max_length=10,
verbose_name=_('Title'),
choices=(
('dr', _('Dr.')),
('prof', _('Prof.')),
),
blank=True,
)
forename = models.CharField(
verbose_name=_('First name'),
max_length=20,
blank=True,
)
surname = models.CharField(
verbose_name=_('Last name'),
max_length=20,
blank=True,
)
nationality = CountryField(
max_length=2,
verbose_name=_('Nationality'),
blank=True,
)
street1 = models.CharField(
verbose_name=_('Street 1'),
max_length=256,
blank=True,
)
street2 = models.CharField(
verbose_name=_('Street 2'),
max_length=256,
blank=True,
)
city = models.CharField(
verbose_name=_('City'),
max_length=256,
blank=True,
)
zip_code = models.CharField(
verbose_name=_('ZIP/Postal code'),
max_length=256,
blank=True,
)
country = CountryField(
max_length=2,
verbose_name=_('Country'),
blank=True,
)
email = models.EmailField(
verbose_name=_('Email'),
blank=True,
)
phone = models.CharField(
verbose_name=_('Phone'),
max_length=256,
blank=True,
)
special_request = models.TextField(
max_length=1024,
verbose_name=_('Special request'),
blank=True,
)
date_from = models.DateTimeField(
verbose_name=_('From'),
blank=True, null=True,
)
date_until = models.DateTimeField(
verbose_name=_('Until'),
blank=True, null=True,
)
creation_date = models.DateTimeField(
verbose_name=_('Creation date'),
auto_now_add=True,
)
booking_id = models.CharField(
max_length=100,
verbose_name=_('Booking ID'),
blank=True,
)
booking_status = models.ForeignKey(
'booking.BookingStatus',
verbose_name=('Booking status'),
blank=True, null=True,
on_delete=models.CASCADE,
)
notes = models.TextField(
max_length=1024,
verbose_name=('Notes'),
blank=True,
)
time_period = models.PositiveIntegerField(
verbose_name=_('Time period'),
blank=True, null=True,
)
time_unit = models.CharField(
verbose_name=_('Time unit'),
default=getattr(settings, 'BOOKING_TIME_INTERVAL', ''),
max_length=64,
blank=True,
)
total = models.DecimalField(
max_digits=36,
decimal_places=2,
verbose_name=_('Total'),
blank=True, null=True,
)
currency = models.CharField(
verbose_name=_('Currency'),
max_length=128,
blank=True,
)
class Meta:
ordering = ['-creation_date']
def __str__(self):
return '#{} ({})'.format(self.booking_id or self.pk,
self.creation_date)
@python_2_unicode_compatible
class BookingError(models.Model):
booking = models.ForeignKey(
Booking,
verbose_name=_('Booking'),
on_delete=models.CASCADE,
)
message = models.CharField(
verbose_name=_('Message'),
max_length=1000,
blank=True,
)
details = models.TextField(
verbose_name=_('Details'),
max_length=4000,
blank=True,
)
date = models.DateTimeField(
verbose_name=_('Date'),
auto_now_add=True,
)
def __str__(self):
return u'[{0}] {1} - {2}'.format(self.date, self.booking.booking_id,
self.message)
@python_2_unicode_compatible
class BookingItem(models.Model):
quantity = models.PositiveIntegerField(
default=1,
verbose_name=_('Quantity'),
)
persons = models.PositiveIntegerField(
verbose_name=_('Persons'),
blank=True, null=True,
)
subtotal = models.DecimalField(
max_digits=36,
decimal_places=2,
verbose_name=_('Subtotal'),
blank=True, null=True,
)
# GFK 'booked_item'
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE,)
object_id = models.PositiveIntegerField()
booked_item = GenericForeignKey('content_type', 'object_id')
booking = models.ForeignKey(
'booking.Booking',
verbose_name=_('Booking'),
on_delete=models.CASCADE,
)
class Meta:
ordering = ['-booking__creation_date']
def __str__(self):
return u'{} ({})'.format(self.booking, self.booked_item)
@property
def price(self):
return self.quantity * self.subtotal
@python_2_unicode_compatible
class ExtraPersonInfo(models.Model):
"""
Model to add extra information of persons/guests to a booking.
:forename: First name of the user.
:surname: Last name of the user.
:arrival: Arrival date of the guest.
:booking: Connection to related booking.
:message: An additional message regarding this person.
"""
forename = models.CharField(
verbose_name=_('First name'),
max_length=20,
)
surname = models.CharField(
verbose_name=_('Last name'),
max_length=20,
)
arrival = models.DateTimeField(
verbose_name=_('Arrival'),
blank=True, null=True,
)
booking = models.ForeignKey(
'booking.Booking',
verbose_name=_('Booking'),
on_delete=models.CASCADE,
)
message = models.TextField(
max_length=1024,
verbose_name=_('Message'),
blank=True,
)
class Meta:
ordering = ['-booking__creation_date']
def __str__(self):
return u'{} {} ({})'.format(self.forename, self.surname, self.booking)
views.py
from django.shortcuts import render
# Create your views here.
"""Views for the booking app."""
from django.contrib.auth.decorators import login_required
from django.contrib.sessions.models import Session
from django.urls import reverse
from django.http import Http404
from django.utils.decorators import method_decorator
from django.views.generic import CreateView, DetailView, ListView
from .forms import BookingForm
from .models import Booking
# ------ MIXINS ------ #
class BookingViewMixin(object):
model = Booking
form_class = BookingForm
# ------ MODEL VIEWS ------ #
class BookingCreateView(BookingViewMixin, CreateView):
"""View to create a new ``Booking`` instance."""
def get_success_url(self):
return reverse('booking_detail', kwargs={'pk': self.object.pk})
def get_form_kwargs(self, *args, **kwargs):
kwargs = super(BookingCreateView, self).get_form_kwargs(
*args, **kwargs)
if self.request.user.is_authenticated:
kwargs.update({'user': self.request.user})
else:
# If the user is not authenticated, get the current session
if not self.request.session.exists(
self.request.session.session_key):
self.request.session.create()
kwargs.update({'session': Session.objects.get(
session_key=self.request.session.session_key)})
return kwargs
class BookingDetailView(BookingViewMixin, DetailView):
"""View to display a ``Booking`` instance."""
def dispatch(self, request, *args, **kwargs):
self.kwargs = kwargs
self.object = self.get_object()
if request.user.is_authenticated:
# If user doesn't own the booking forbid access
if not self.object.user == request.user:
raise Http404
else:
# If anonymous doesn't own the booking forbid access
session = self.object.session
if (not session or not request.session.session_key or
session.session_key != request.session.session_key):
raise Http404
return super(BookingViewMixin, self).dispatch(request, *args, **kwargs)
class BookingListView(BookingViewMixin, ListView):
"""View to display all ``Booking`` instances of one user."""
@method_decorator(login_required)
def dispatch(self, request, *args, **kwargs):
return super(BookingViewMixin, self).dispatch(request, *args, **kwargs)
def get_queryset(self):
return self.request.user.bookings.all()
答案 0 :(得分：1)
根据我的经验，当 str 函数中使用的至少一个变量为None时，会发生此错误。从外壳检查数据库中所有模型中的对象，并查找 str 函数中提到的变量。如果其中任何一个为“无”，请修复它。请注意，在访问与故障对象无关的页面时，您可能会遇到此错误。祝你好运