# -*- coding: utf-8 -*-
"""
flask.views
~~~~~~~~~~~
This module provides class-based views inspired by the ones in Django.
#参考Djnago的View类做法，继承View类实现视图函数
"""
from ._compat import with_metaclass
from .globals import request
http_method_funcs = frozenset(
["get", "post", "head", "options", "delete", "put", "trace", "patch"]
)
class View(object):
"""
#用as_view()的例子
class MyView(View):
methods = ['GET']
def dispatch_request(self, name):
return 'Hello %s!' % name
app.add_url_rule('/hello/<name>', view_func=MyView.as_view('myview'))
添加装饰器的例子
class SecretView(View):
methods = ['GET']
decorators = [superuser_required]
def dispatch_request(self):
...
"""
methods = None #接受的请求方法(list)
provide_automatic_options = None
decorators = () #自己添加的装饰器函数，装饰as_view()的返回值
def dispatch_request(self):
#子类重载方法实现实际的视图函数
raise NotImplementedError()#不重载方法报错
#as_view实现函数
@classmethod
def as_view(cls, name, *class_args, **class_kwargs):
def view(*args, **kwargs):
self = view.view_class(*class_args, **class_kwargs)
return self.dispatch_request(*args, **kwargs)
if cls.decorators:
view.__name__ = name
view.__module__ = cls.__module__
for decorator in cls.decorators:
view = decorator(view)
view.view_class = cls
view.__name__ = name
view.__doc__ = cls.__doc__
view.__module__ = cls.__module__
view.methods = cls.methods
view.provide_automatic_options = cls.provide_automatic_options
return view
class MethodViewType(type):
"""Metaclass for :class:`MethodView` that determines what methods the view
defines.
"""
def __init__(cls, name, bases, d):
super(MethodViewType, cls).__init__(name, bases, d)
if "methods" not in d:
methods = set()
for base in bases:
if getattr(base, "methods", None):
methods.update(base.methods)
for key in http_method_funcs:
if hasattr(cls, key):
methods.add(key.upper())
if methods:
cls.methods = methods
class MethodView(with_metaclass(MethodViewType, View)):
"""A class-based view that dispatches request methods to the corresponding
class methods. For example, if you implement a ``get`` method, it will be
used to handle ``GET`` requests. ::
class CounterAPI(MethodView):
def get(self):
return session.get('counter', 0)
def post(self):
session['counter'] = session.get('counter', 0) + 1
return 'OK'
app.add_url_rule('/counter', view_func=CounterAPI.as_view('counter'))
"""
def dispatch_request(self, *args, **kwargs):
meth = getattr(self, request.method.lower(), None)
# If the request method is HEAD and we don't have a handler for it
# retry with GET.
if meth is None and request.method == "HEAD":
meth = getattr(self, "get", None)
assert meth is not None, "Unimplemented method %r" % request.method
return meth(*args, **kwargs)
