如何在多个上下文对象中选择并分页get_context_data？

Question

我正在尝试分页从视图.py，从多个上下文对象中进行选择。代码示例条件语句中只显示了两个选项，但我还有几个选项，基本上涵盖了表单提交中的所有选项。但是，最后只返回一个上下文，将上下文传递给模板视图进行分页。在

我还尝试在中全局设置分页设置.py，但它不起作用。在

我以前看过下面的文章，作为getcontext对象分页的指南。在

How to perform pagination for context object in django?

从视图.py公司名称：

from django.shortcuts import render
import django.views.generic
from django.http import HttpResponse
from django.template import loader
from django.template import RequestContext
from ephemera.models import *
from ephemera.serializers import ItemSerializer
from rest_framework import generics
from ephemera.forms import SearchForm, AdvSearchForm
from itertools import chain
from django.core.paginator import Paginator
from django.core.paginator import EmptyPage
from django.core.paginator import PageNotAnInteger



class SearchResultsAdvancedView(django.views.generic.ListView): 
    template_name = 'ephemera/searchresults_advanced.html'
    form = AdvSearchForm()
    paginate_by = 10
    model = Item

    def get_context_data(self, **kwargs):       
        context = super(SearchResultsAdvancedView, self).get_context_data(**kwargs)

        choose_collection = self.request.GET.get('choose_collection')
        user_input = self.request.GET.get('user_input')
        choose_item = self.request.GET.get('choose_item')

        bookpage = False
        imagepage = False

        if choose_collection == 'All' and user_input == '' and choose_item == 'book':
            context['book_qs'] = Item.objects.raw('SELECT  * FROM   ephemera_item WHERE ephemera_item.material_type LIKE %s', ['book']);    
            bookpage = True
        elif choose_collection == 'All' and user_input == '' and choose_item == 'image':
            context['image_qs'] = Item.objects.raw('SELECT  * FROM   ephemera_item WHERE ephemera_item.material_type LIKE %s', ['image']);  
            imagepage = True

        if bookpage:
            paginator = Paginator(context, self.paginate_by)            
            page = self.request.GET.get('page')
            try:
                book_qs = paginator.page(page)
            except PageNotAnInteger:
                book_qs = paginator.page(1)
            except EmptyPage:
                book_qs = paginator.page(paginator.num_pages)
            context['book_qs'] = book_qs

        elif imagepage:
            paginator = Paginator(context, self.paginate_by)            
            page = self.request.GET.get('page')
            try:
                image_qs = paginator.page(page)
            except PageNotAnInteger:
                image_qs = paginator.page(1)
            except EmptyPage:
                image_qs = paginator.page(paginator.num_pages)
            context['image_qs'] = image_qs

        return context

返回的错误包括：

异常值：不可损坏类型：“切片”

异常位置：c:\users\administrator\appdata\local\programs\python36-32\lib\site packages\django\core\分页器.py第70行

Answer 1

这里不需要使用^{} [Django-doc]，您可以重写^{} [Django-doc]和{a3}来确定模板中列表的名称：

class SearchResultsAdvancedView(django.views.generic.ListView): 
    template_name = 'ephemera/searchresults_advanced.html'
    form = AdvSearchForm()
    paginate_by = 10
    model = Item

    def item_type(self):
        choose_collection = self.request.GET.get('choose_collection')
        if choose_collection != 'All' or not self.request.GET.get('user_input'):
            return None
        choose_item = self.request.GET.get('choose_item')
        if choose_item in ('book', 'image'):
            return choose_item
        return None

    def get_queryset(self, *args, **kwargs):
        item_type = self.get_item_type()
        qs = super.get_queryset(*args, **kwargs)
        if item_type is not None:
            return qs.filter(material_type__iexact=item_type)
        return qs.none()

    def get_context_object_name(self, object_list):
        item_type = self.get_item_type()
        if item_type is not None:
            return '{}_qs'.format(item_type)
        return super().get_context_object_name(object_list)

Django的逻辑将分页QuerySet本身，因此您不必担心这一点。这是由于^{} [Django-doc]实现了^{} [Django-doc]：

def get_context_data(self, *, object_list=None, **kwargs):
    """Get the context for this view."""
    queryset = object_list if object_list is not None else self.object_list
    page_size = self.get_paginate_by(queryset)
    context_object_name = self.get_context_object_name(queryset)
    if page_size:
        paginator, page, queryset, is_paginated = self.paginate_queryset(queryset, page_size)
        context = {
            'paginator': paginator,
            'page_obj': page,
            'is_paginated': is_paginated,
            'object_list': queryset
        }
    else:
        context = {
            'paginator': None,
            'page_obj': None,
            'is_paginated': False,
            'object_list': queryset
        }
    if context_object_name is not None:
        context[context_object_name] = queryset
    context.update(kwargs)
    return super().get_context_data(**context)

话虽如此，我的印象是造型不是很好。如果您有项目类型，那么定义一个ItemType模型是非常重要的。此外，最好使用Django的ORM生成查询，而不是原始查询。在

Answer 2

原始代码示例中的一个问题是RawQuerySets不适用于get_context_data中显示的分页代码，这些代码应该是带有过滤器的模型对象，否则分页代码将失败。例如

    mydata = self.model.objects.filter(material_type__icontains = 'book')

然而，在这种情况下，RawQuerySets是必需的，并且很有用，因为附加的（未显示）查询具有复杂的内部连接等，使用过滤器很难完成。在

One solution for casting a raw query set as a list for pagination is answered in:

另外，RawQuerySet的django paginator模块也可以用来帮助解决这篇文章中链接的问题。在

django-paginator-rawqueryset

在模块的帮助下，原始查询集可以有效地与给定的分页器代码一起使用，以利用上下文对象返回要传递给模板的上下文。然后，模板和显示页面导航的典型代码一起，还能够利用附加到上下文的变量来根据需要显示数据。在

^{pr2}$

显示的问题示例，来自视图.py，有点“暴力”，可以在类内定义的帮助下进行更紧凑的编码，如第一个答案所示。这里显示了使用另一个模块解决问题的方法：

    from rawpaginator.paginator import Paginator
    from django.core.paginator import EmptyPage
    from django.core.paginator import PageNotAnInteger


    class SearchResultsAdvancedView(django.views.generic.ListView): 
        template_name = 'ephemera/searchresults_advanced.html'
        form = AdvSearchForm()
        paginate_by = 10
        model = Item

        def get_context_data(self, **kwargs):       
            context = super(SearchResultsAdvancedView, self).get_context_data(**kwargs)

            choose_collection = self.request.GET.get('choose_collection')
            user_input = self.request.GET.get('user_input')
            choose_item = self.request.GET.get('choose_item')

            bookpage = False
            imagepage = False

            if choose_collection == 'All' and user_input == '' and choose_item == 'book':
                mydata = Item.objects.raw('SELECT  * FROM   ephemera_item WHERE ephemera_item.material_type LIKE %s', ['book']);    
                bookpage = True
            elif choose_collection == 'All' and user_input == '' and choose_item == 'image':
                mydata = Item.objects.raw('SELECT  * FROM   ephemera_item WHERE ephemera_item.material_type LIKE %s', ['image']);  
                imagepage = True

             paginator = Paginator(mydata, self.paginate_by)            
             page = self.request.GET.get('page')

            if bookpage:
                try:
                    book_qs = paginator.page(page)
                except PageNotAnInteger:
                    book_qs = paginator.page(1)
                except EmptyPage:
                    book_qs = paginator.page(paginator.num_pages)
                context['book_qs'] = book_qs

            elif imagepage:
                try:
                    image_qs = paginator.page(page)
                except PageNotAnInteger:
                    image_qs = paginator.page(1)
                except EmptyPage:
                    image_qs = paginator.page(paginator.num_pages)
                context['image_qs'] = image_qs

            return context