Django中的DRY视图

Question

我已经构建了一个应用程序，它有许多类似的视图，应该能够使用相同的基本代码。然而，每种方法在方法中的各种拐点处都有一些独特的特征，这样我就不能找出一种方法来构造这个来真正重用任何代码。相反，我创建了一个剪切粘贴方法，并分别调整每种方法。这部分应用程序是我编写的第一批Python代码中的一部分，并且知道必须有更好的方法来做到这一点，但是我被锁定在这样做和“它工作”，所以我看不到出路。

下面介绍一下基本视图模板基本上是这样的：

def view_entity(request, entity_id=None): 
    if request.method == 'POST': 
     return _post_entity(request, entity_id) 
    else: 
     return _get_entity(request, entity_id) 

def _get_entity(request, entity_id): 
    data = _process_entity(request, entity_id) 
    if 'redirect' in data: 
     return data['redirect'] 
    else: 
     return _render_entity(request, data['form']) 

def _post_entity(request, entity_id): 
    data = _process_entity(request, entity_id) 
    if 'redirect' in data: 
     return data['redirect'] 
    elif data['form'].is_valid(): 
     # custom post processing here 
     instance = data['form'].save() 
     return HttpResponseRedirect(reverse('entity', args=[instance.id])) 
    else: 
     return _render_entity(request, data['form']) 


def _process_entity(request, entity_id): 
    data = {} 

    if entity_id != 'new': # READ/UPDATE 
     # sometimes there's custom code to retrieve the entity 
     e = entity_id and get_object_or_404(Entity.objects, pk=entity_id) 
     # sometimes there's custom code here that deauthorizes e 
     # sometimes extra values are added to data here (e.g. parent entity) 
     if e: 
      if request.method == 'POST': 
       data['form'] = EntityForm(request.POST, instance=e) 
       # sometimes there's a conditional here for CustomEntityForm 
      else: 
       data['form'] = EntityForm(instance=e) 
     else: # user not authorized for this entity 
      return {'redirect': HttpResponseRedirect(reverse('home'))} 
     # sometimes there's custom code here for certain entity types 

    else: # CREATE 
     if request.method == 'POST': 
      data['form'] = EntityForm(request.POST) 
     else: 
      data['form'] = EntityForm() 

    # sometimes extra key/values are added to data here 
    return data 

我甚至没有包括所有可能的变化，但你可以看到，_process_entity方法需要基于大量的个人定制正在处理的实体的类型。这是我无法弄清楚这种干扰方式的主要原因。

任何帮助表示赞赏，谢谢！

Answer 1

所以我最终重构代码到一个基类，我的所有视图继承。我没有最终重构到多个视图（但），而是通过在处理方法中插入钩子来解决定制处理方法的问题。

下面是从DetailView继承了基类的要点：

class MyDetailView(DetailView): 
    context = {} 

    def get(self, request, *args, **kwargs): 
     self._process(request, *args, **kwargs) 

     if 'redirect' in self.context: 
      return HttpResponseRedirect(self.context['redirect']) 

     else: 
      return self._render(request, *args, **kwargs) 

    def post(self, request, *args, **kwargs): 
     self._process(request, *args, **kwargs) 

     if 'redirect' in self.context: 
      return HttpResponseRedirect(self.context['redirect']) 

     elif self.context['form'].is_valid(): 
      self._get_hook('_pre_save')(request, *args, **kwargs) 
      return self._save(request, *args, **kwargs) 

     else: 
      return self._render(request, *args, **kwargs) 

    def _process(self, request, *args, **kwargs): 
     form = getattr(app.forms, '%sForm' % self.model.__name__) 

     if kwargs['pk'] != 'new': # READ/UPDATE 
      self.object = self.get_object(request, *args, **kwargs) 

      self._get_hook('_auth')(request, *args, **kwargs) 

      if not self.object: # user not authorized for this entity 
       return {'redirect': reverse(
        '%s_list' % self.model.__name__.lower())} 

     self.context['form'] = form(
      data=request.POST if request.method == 'POST' else None, 
      instance=self.object if hasattr(self, 'object') else None) 

     self._get_hook('_post_process')(request, *args, **kwargs) 

    def _get_hook(self, hook_name): 
     try: 
      return getattr(self, '%s_hook' % hook_name) 
     except AttributeError, e: 
      def noop(*args, **kwargs): 
       pass 
      return noop 

的关键部分要注意的是_get_hook方法和我使用其他方法中的地方。这样一来，在一些复杂的观点，我可以注入自定义代码：

class ComplexDetailView(MyDetailView): 
    def _post_process_hook(self, request, *args, **kwargs): 
     # here I can add stuff to self.context using 
     # self.model, self.object, request.POST or whatever 

这使我的自定义视图小，因为它们继承了大部分的功能，但我可以添加任何的调整是必要的特定视图。

Answer 2

使用基于类的视图。您可以使用类的继承和其他功能来使您的视图更加可重用。您还可以使用内置的通用视图来简化一些基本任务。

检查class-based views documentation。你也可以阅读这this