221 lines
7.8 KiB
Python
221 lines
7.8 KiB
Python
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from django.core.exceptions import ImproperlyConfigured
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from django.core.paginator import InvalidPage, Paginator
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from django.db.models import QuerySet
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from django.http import Http404
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from django.utils.translation import gettext as _
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from django.views.generic.base import ContextMixin, TemplateResponseMixin, View
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class MultipleObjectMixin(ContextMixin):
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"""A mixin for views manipulating multiple objects."""
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allow_empty = True
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queryset = None
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model = None
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paginate_by = None
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paginate_orphans = 0
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context_object_name = None
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paginator_class = Paginator
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page_kwarg = "page"
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ordering = None
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def get_queryset(self):
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"""
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Return the list of items for this view.
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The return value must be an iterable and may be an instance of
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`QuerySet` in which case `QuerySet` specific behavior will be enabled.
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"""
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if self.queryset is not None:
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queryset = self.queryset
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if isinstance(queryset, QuerySet):
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queryset = queryset.all()
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elif self.model is not None:
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queryset = self.model._default_manager.all()
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else:
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raise ImproperlyConfigured(
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"%(cls)s is missing a QuerySet. Define "
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"%(cls)s.model, %(cls)s.queryset, or override "
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"%(cls)s.get_queryset()." % {"cls": self.__class__.__name__}
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)
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ordering = self.get_ordering()
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if ordering:
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if isinstance(ordering, str):
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ordering = (ordering,)
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queryset = queryset.order_by(*ordering)
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return queryset
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def get_ordering(self):
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"""Return the field or fields to use for ordering the queryset."""
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return self.ordering
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def paginate_queryset(self, queryset, page_size):
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"""Paginate the queryset, if needed."""
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paginator = self.get_paginator(
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queryset,
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page_size,
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orphans=self.get_paginate_orphans(),
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allow_empty_first_page=self.get_allow_empty(),
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)
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page_kwarg = self.page_kwarg
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page = self.kwargs.get(page_kwarg) or self.request.GET.get(page_kwarg) or 1
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try:
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page_number = int(page)
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except ValueError:
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if page == "last":
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page_number = paginator.num_pages
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else:
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raise Http404(
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_("Page is not “last”, nor can it be converted to an int.")
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)
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try:
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page = paginator.page(page_number)
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return (paginator, page, page.object_list, page.has_other_pages())
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except InvalidPage as e:
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raise Http404(
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_("Invalid page (%(page_number)s): %(message)s")
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% {"page_number": page_number, "message": str(e)}
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)
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def get_paginate_by(self, queryset):
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"""
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Get the number of items to paginate by, or ``None`` for no pagination.
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"""
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return self.paginate_by
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def get_paginator(
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self, queryset, per_page, orphans=0, allow_empty_first_page=True, **kwargs
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):
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"""Return an instance of the paginator for this view."""
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return self.paginator_class(
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queryset,
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per_page,
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orphans=orphans,
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allow_empty_first_page=allow_empty_first_page,
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**kwargs,
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)
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def get_paginate_orphans(self):
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"""
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Return the maximum number of orphans extend the last page by when
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paginating.
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"""
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return self.paginate_orphans
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def get_allow_empty(self):
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"""
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Return ``True`` if the view should display empty lists and ``False``
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if a 404 should be raised instead.
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"""
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return self.allow_empty
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def get_context_object_name(self, object_list):
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"""Get the name of the item to be used in the context."""
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if self.context_object_name:
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return self.context_object_name
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elif hasattr(object_list, "model"):
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return "%s_list" % object_list.model._meta.model_name
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else:
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return None
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def get_context_data(self, *, object_list=None, **kwargs):
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"""Get the context for this view."""
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queryset = object_list if object_list is not None else self.object_list
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page_size = self.get_paginate_by(queryset)
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context_object_name = self.get_context_object_name(queryset)
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if page_size:
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paginator, page, queryset, is_paginated = self.paginate_queryset(
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queryset, page_size
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)
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context = {
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"paginator": paginator,
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"page_obj": page,
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"is_paginated": is_paginated,
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"object_list": queryset,
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}
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else:
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context = {
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"paginator": None,
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"page_obj": None,
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"is_paginated": False,
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"object_list": queryset,
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}
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if context_object_name is not None:
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context[context_object_name] = queryset
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context.update(kwargs)
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return super().get_context_data(**context)
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class BaseListView(MultipleObjectMixin, View):
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"""A base view for displaying a list of objects."""
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def get(self, request, *args, **kwargs):
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self.object_list = self.get_queryset()
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allow_empty = self.get_allow_empty()
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if not allow_empty:
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# When pagination is enabled and object_list is a queryset,
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# it's better to do a cheap query than to load the unpaginated
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# queryset in memory.
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if self.get_paginate_by(self.object_list) is not None and hasattr(
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self.object_list, "exists"
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):
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is_empty = not self.object_list.exists()
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else:
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is_empty = not self.object_list
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if is_empty:
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raise Http404(
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_("Empty list and “%(class_name)s.allow_empty” is False.")
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% {
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"class_name": self.__class__.__name__,
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}
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)
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context = self.get_context_data()
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return self.render_to_response(context)
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class MultipleObjectTemplateResponseMixin(TemplateResponseMixin):
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"""Mixin for responding with a template and list of objects."""
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template_name_suffix = "_list"
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def get_template_names(self):
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"""
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Return a list of template names to be used for the request. Must return
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a list. May not be called if render_to_response is overridden.
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"""
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try:
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names = super().get_template_names()
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except ImproperlyConfigured:
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# If template_name isn't specified, it's not a problem --
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# we just start with an empty list.
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names = []
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# If the list is a queryset, we'll invent a template name based on the
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# app and model name. This name gets put at the end of the template
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# name list so that user-supplied names override the automatically-
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# generated ones.
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if hasattr(self.object_list, "model"):
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opts = self.object_list.model._meta
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names.append(
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"%s/%s%s.html"
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% (opts.app_label, opts.model_name, self.template_name_suffix)
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)
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elif not names:
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raise ImproperlyConfigured(
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"%(cls)s requires either a 'template_name' attribute "
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"or a get_queryset() method that returns a QuerySet."
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% {
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"cls": self.__class__.__name__,
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}
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)
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return names
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class ListView(MultipleObjectTemplateResponseMixin, BaseListView):
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"""
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Render some list of objects, set by `self.model` or `self.queryset`.
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`self.queryset` can actually be any iterable of items, not just a queryset.
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"""
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