django通用视图的DetailView

SingleObjectMixin

主要功能：

1. def get_queryset(self):

   返回query_set里的所有对象
   如果提供的

   queryset

   为空且

   model

   不为空，返回

   self.model._default_manager.all()

   • 提供了

     queryset

     ，返回

     self.queryset.all()

2. get_object(self, queryset=None)

   :根据请求url里的关键字参数pk或者slug过滤query_set来获取单一对象（obj）

   queryset = queryset.filter(pk=pk) 或者 queryset = queryset.filter(**{slug_field: slug})
   obj = queryset.get()
   return obj

3. def get_context_data(self, **kwargs):

   将对象（obj）其插入到渲染模板所需的上下文中

   self.object = self.get_object
   context['object'] = self.object
   # 或者可以自定义对象名,两者是同时存在的：
   context[context_object_name] = self.object

class SingleObjectMixin(ContextMixin):
"""
提供了可以操纵检索单一对象的能力
"""
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):
# 根据pk和slug查找object
# 如果自定义了queryset就使用它，这是子类需要的
# 比如DateDetailView
if queryset is None:
queryset = self.get_queryset()

# 接着试着查询pk
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)

# 接着试着查询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_context_data(self, **kwargs):
"""插入单一对象到上下文字典中"""
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)

BaseDetailView

BaseDetailView

SingleObjectMixin

view

class BaseDetailView(SingleObjectMixin, View):
"""一个展示单一对象的基本视图"""
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)

SingleObjectTemplateResponseMixin

SingleObjectTemplateResponseMixin主要是重写了

get_template_names

app_label + model_name(小写) + template_name_suffix(_detail)

class SingleObjectTemplateResponseMixin(TemplateResponseMixin):
template_name_field = None
template_name_suffix = '_detail'

def get_template_names(self):
# 省略....
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
))

return names

DetailView

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()`.
"""

总结

1. SingleObjectMixin.get_context_data

   获取含有单个对象的上下文(

   context

   )

2. SingleObjectTemplateResponseMixin.render_to_response

   利用上下文进行渲染并返回响应,并重写其

   get_template_names方法

3. BaseDetailView组合SingleObjectMixin和View

   并实现

   get

   请求和分发

4. DetailView

   组合

   SingleObjectTemplateResponseMixin

   和

   BaseDetailView

   实现完整的逻辑处理