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第八章 FBVS & CBVS

如何选择 function - views 和 class - views

见流程图：

urlconf 中不要包含 views 的逻辑

Bad example :
from django.conf.urls import url
from django.views.generic import DetailView
from tastings.models import Tasting
urlpatterns = [
  url(r"^(?P<pk>\d+)/$",
    DetailView.as_view(
    model=Tasting,
    template_name="tastings/detail.html"),
    name="detail"),
  url(r"^(?P<pk>\d+)/results/$",
    DetailView.as_view(
    model=Tasting,
    template_name="tastings/results.html"),
    name="results"),
]

优点:

• 在 views 避免了重复的代码
• 松耦合
• url 集中处理路由问题
• views 可以得到 class-based views 的所有优点
• 更加灵活

使用url name space 更好的管理 url

url(r'^detail/', include('tastings.urls', namespace='tastings')),

通过 tastings:detail 调用。

url设计原则：

• url 尽量短小，明显
• 更容易搜索，更新，重构

不要在url 中使用 string的 views路径

url(r'^$', 'polls.views.index', name='index'),

• 当views 有错误时，导致调试困难
• Instructors have to explain to beginners the need for an empty string at the beginning of the urlpatterns variable。

将业务逻辑移除 views 便于管理复用

尽量不要使用locals() 作为 Views Context

• 有可能会污染 template 变量环境
• 当变量较多时，消耗不必要的资源

第九章 Function-based views 最佳实践

编写function-based views 建议

• 保持views 的最小代码量
• 在views 中不要重复的代码
• views 中保留着表现逻辑，业务逻辑尽可能的在models、form层。
• 使用 function-based views 编写自定义的 错误处理（403, 404, and 500 error handlers.）
• 避免负责逻辑的嵌套。

通过 request、response 对象来传递属性值。

function-based views 可以更好的利用装饰器

第十章 Class-based views 最佳实践

编写class-based views 建议

• 保持views 的最小代码量
• 在views 中不要重复的代码
• views 中保留着表现逻辑，业务逻辑尽可能的在models、form层。
• 不要使用class-based views，使用 function-based views 编写自定义的 错误处理（403, 404, and 500 error handlers.）
• 使 mixins 最小化。

mixins 使用排序： python-object, mixins , base-views

class FruityFlavorView(FreshFruitMixin, TemplateView):
template_name = "fruity_flavor.html"

什么时候使用什么视图

Name	Purpose	Two Scoops Example
View	Base view or handy view that can be used foranything.	See section 10.6, `Using Justdjango.views.generic.View'.
RedirectView	Redirect user to another URL	Send users who visit /log-in/' to/login/'.
TemplateView	Display a Django HTML template.	The `/about/' page of our site.
ListView	List objects	List of ice cream flavors.
DetailView	Display an object	Details on an ice cream flavor.
FormView	Submit a form	The site's contact or email form.
CreateView	Create an object	Create a new ice cream flavor.
UpdateView	Update an object	Update an existing ice cream flavor.
DeleteView	Delete an object	Delete an unpleasant ice cream flavorlike Vanilla Steak.
Generic date views	For display of objects that occur over a rangeof time.	Blogs are a common reason to usethem. For Two Scoops, we could create a public history of when flavors havebeen added to the database.

使用 LoginRequiredMixin 来进行用户认证

class FlavorDetailView(LoginRequiredMixin, DetailView):
    model = Flavor

将多个视图都需要重写的方法放入到 mixin 中，以保证视图的简单清晰

from django.contrib import messages
from django.views.generic import CreateView, UpdateView, DetailView
from braces.views import LoginRequiredMixin
from .models import Flavor

class FlavorActionMixin(object):
    fields = ('title', 'slug', 'scoops_remaining')

    @property
    def success_msg(self):
        return NotImplemented
    
    def form_valid(self, form):
        messages.info(self.request, self.success_msg)
        return super(FlavorActionMixin, self).form_valid(form)

class FlavorCreateView(LoginRequiredMixin, FlavorActionMixin,
CreateView):
    model = Flavor
    success_msg = "Flavor created!"

class FlavorUpdateView(LoginRequiredMixin, FlavorActionMixin,
UpdateView):
    model = Flavor
    success_msg = "Flavor updated!"

ps： 感觉本书views 这里讲的比较乱, 部分class-based views 可参见另一篇博文： Django class views (opens new window)