列出超出范围的索引django答案

【问题标题】：list index out of range django列出超出范围的索引django
【发布时间】：2017-04-05 13:02:45
【问题描述】：

谁能解释我为什么要回来list index out of range，在我看来它出现在两个地方，第一个是context_data = self.get_context_data(user_id, month, year, form=form) 和context['month'] = calendar.month_name[month]，所以有人可以解释一下我的代码中发生了什么。这是完整的Traceback

我的看法：

import calendar
import datetime

from django.contrib import messages
from django.contrib.auth.models import User
from django.core.urlresolvers import reverse
from django.http import HttpResponseForbidden
from django.shortcuts import redirect, get_object_or_404
from django.views.generic.edit import FormView

from .helpers.user_util import get_user_full_name_or_user_name
from models import Rate
from statistics.forms import CommissionsMonthSelectionForm
from statistics.services import ManagerCommissionsProjectsCalculation, CommissionsAccessService


class UserSalesCommissionsView(FormView):
    template_name = "statistics/user_sales_commissions.html"
    form_class = CommissionsMonthSelectionForm
    currency = Rate.EUR

    def get(self, request, *args, **kwargs):
        user_id = self.kwargs['user_id']
        requesting_user = request.user
        if CommissionsAccessService.can_view_commissions_page(requesting_user, user_id):
            month = int(self.request.GET.get('month', datetime.datetime.now().month))
            year = int(self.request.GET.get('year', datetime.datetime.now().year))
            form = CommissionsMonthSelectionForm(initial={'year': year, 'month': month})
            context_data = self.get_context_data(user_id, month, year, form=form)
            return self.render_to_response(context_data)
        else:
            return HttpResponseForbidden('Access denied')

    def post(self, request, *args, **kwargs):
        user_id = self.kwargs['user_id']
        requesting_user = self.request.user

        if CommissionsAccessService.can_view_commissions_page(requesting_user, user_id):
            form_class = self.get_form_class()
            form = self.get_form(form_class)
            if form.is_valid():
                return self.form_valid(form, user_id)
            else:
                return self.form_invalid(form)
        else:
            return HttpResponseForbidden('Access denied')

    def form_valid(self, form, user_id=None):
        year = form.cleaned_data['year']
        month = form.cleaned_data['month']
        return redirect(self.get_success_url(user_id, month, year))

    def form_invalid(self, form):
        messages.add_message(self.request, messages.ERROR,
                             "Invalid data. Please check fields.")
        return self.render_to_response(
            self.get_context_data(form=form)
        )

    def get_success_url(self,
                        user_id=None,
                        year=datetime.datetime.now().year,
                        month=datetime.datetime.now().month):
        return reverse("vinclucms_statistics:manager_commissions_statistics", user_id) + \
               "?month=" + str(month) + "&year=" + str(year)

    def get_context_data(self,
                         user_id=None,
                         year=datetime.datetime.now().year,
                         month=datetime.datetime.now().month,
                         **kwargs):
        context = super(UserSalesCommissionsView, self).get_context_data(**kwargs)
        context['user_name'] = get_user_full_name_or_user_name(get_object_or_404(User, pk=user_id))
        context['can_view'] = True
        context['currency'] = self.currency
        context['month'] = calendar.month_name[month]
        context['year'] = year

        context['commissions'] = ManagerCommissionsProjectsCalculation.get_project_list(
            self.currency, year, month, user_id)
        return context

查看网址：

url(r'^statistics/commissions/sales/(?P<user_id>[^/]+?)/$', login_required(views.UserSalesCommissionsView.as_view()), name='user_sales_commissions')

【问题讨论】：

标签： python django

【解决方案1】：

这是get_context_data的定义：

def get_context_data(self,
                     user_id=None,
                     year=datetime.datetime.now().year,
                     month=datetime.datetime.now().month,
                     **kwargs):

这就是它的名称：

context_data = self.get_context_data(user_id, month, year, form=form)

所以 2 个关键字参数（year 和 month）被反转为类似 calendar.month_name[2017] 的东西，它会吐出 Indexerror。

您应该以正确的顺序传递参数，或者在处理关键字参数时，始终指定它们的名称：

context_data = self.get_context_data(user_id=user_id, month=month, year=year, form=form)

这样他们的顺序就不再重要了。

可能还想检查PEP 3102。

【讨论】：

是的，我已经调试过了，发现他反了，谢谢解释

【解决方案2】：

month = datetime.datetime.now().month # IF Current month is April then month==4

calendar.month_name[month]

表示当前语言环境中一年中月份的数组。这遵循 1 月为第 1 个月的常规约定，因此它的长度为 13，而 month_name[0] 是空字符串。

在这里：calendar.month_name[month] 检查month 的值是多少，它应该是 4，因为当前月份是四月。

因此，您在需要日期时间对象的地方传递字符串。

【讨论】：