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from django.core.exceptions import ImproperlyConfigured
from django.db import models
from django.http import Http404
from django.utils.translation import gettext as _
from django.views.generic.base import ContextMixin, TemplateResponseMixin, View
class SingleObjectMixin(ContextMixin):
"""
Provide the ability to retrieve a single object for further manipulation.
"""
model = None
queryset = None
slug_field = "slug"
context_object_name = None
slug_url_kwarg = "slug"
pk_url_kwarg = "pk"
query_pk_and_slug = False
def get_object(self, queryset=None):
"""
Return the object the view is displaying.
Require `self.queryset` and a `pk` or `slug` argument in the URLconf.
Subclasses can override this to return any object.
"""
# Use a custom queryset if provided; this is required for subclasses
# like DateDetailView
if queryset is None:
queryset = self.get_queryset()
# Next, try looking up by primary key.
pk = self.kwargs.get(self.pk_url_kwarg)
slug = self.kwargs.get(self.slug_url_kwarg)
if pk is not None:
queryset = queryset.filter(pk=pk)
# Next, try looking up by slug.
if slug is not None and (pk is None or self.query_pk_and_slug):
slug_field = self.get_slug_field()
queryset = queryset.filter(**{slug_field: slug})
# If none of those are defined, it's an error.
if pk is None and slug is None:
raise AttributeError(
"Generic detail view %s must be called with either an object "
"pk or a slug in the URLconf." % self.__class__.__name__
)
try:
# Get the single item from the filtered queryset
obj = queryset.get()
except queryset.model.DoesNotExist:
raise Http404(
_("No %(verbose_name)s found matching the query")
% {"verbose_name": queryset.model._meta.verbose_name}
)
return obj
def get_queryset(self):
"""
Return the `QuerySet` that will be used to look up the object.
This method is called by the default implementation of get_object() and
may not be called if get_object() is overridden.
"""
if self.queryset is None:
if self.model:
return self.model._default_manager.all()
else:
raise ImproperlyConfigured(
"%(cls)s is missing a QuerySet. Define "
"%(cls)s.model, %(cls)s.queryset, or override "
"%(cls)s.get_queryset()." % {"cls": self.__class__.__name__}
)
return self.queryset.all()
def get_slug_field(self):
"""Get the name of a slug field to be used to look up by slug."""
return self.slug_field
def get_context_object_name(self, obj):
"""Get the name to use for the object."""
if self.context_object_name:
return self.context_object_name
elif isinstance(obj, models.Model):
return obj._meta.model_name
else:
return None
def get_context_data(self, **kwargs):
"""Insert the single object into the context dict."""
context = {}
if self.object:
context["object"] = self.object
context_object_name = self.get_context_object_name(self.object)
if context_object_name:
context[context_object_name] = self.object
context.update(kwargs)
return super().get_context_data(**context)
class BaseDetailView(SingleObjectMixin, View):
"""
Base view for displaying a single object.
This requires subclassing to provide a response mixin.
"""
def get(self, request, *args, **kwargs):
self.object = self.get_object()
context = self.get_context_data(object=self.object)
return self.render_to_response(context)
class SingleObjectTemplateResponseMixin(TemplateResponseMixin):
template_name_field = None
template_name_suffix = "_detail"
def get_template_names(self):
"""
Return a list of template names to be used for the request. May not be
called if render_to_response() is overridden. Return a list containing
``template_name``, if set on the value. Otherwise, return a list
containing:
* the contents of the ``template_name_field`` field on the
object instance that the view is operating upon (if available)
* ``<app_label>/<model_name><template_name_suffix>.html``
"""
try:
names = super().get_template_names()
except ImproperlyConfigured:
# If template_name isn't specified, it's not a problem --
# we just start with an empty list.
names = []
# If self.template_name_field is set, grab the value of the field
# of that name from the object; this is the most specific template
# name, if given.
if self.object and self.template_name_field:
name = getattr(self.object, self.template_name_field, None)
if name:
names.insert(0, name)
# The least-specific option is the default <app>/<model>_detail.html;
# only use this if the object in question is a model.
if isinstance(self.object, models.Model):
object_meta = self.object._meta
names.append(
"%s/%s%s.html"
% (
object_meta.app_label,
object_meta.model_name,
self.template_name_suffix,
)
)
elif getattr(self, "model", None) is not None and issubclass(
self.model, models.Model
):
names.append(
"%s/%s%s.html"
% (
self.model._meta.app_label,
self.model._meta.model_name,
self.template_name_suffix,
)
)
# If we still haven't managed to find any template names, we should
# re-raise the ImproperlyConfigured to alert the user.
if not names:
raise ImproperlyConfigured(
"SingleObjectTemplateResponseMixin requires a definition "
"of 'template_name', 'template_name_field', or 'model'; "
"or an implementation of 'get_template_names()'."
)
return names
class DetailView(SingleObjectTemplateResponseMixin, BaseDetailView):
"""
Render a "detail" view of an object.
By default this is a model instance looked up from `self.queryset`, but the
view will support display of *any* object by overriding `self.get_object()`.
"""
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