Django 阅读源码笔记 - Hypers第一周

os.environ["DJANGO_SETTINGS_MODULE"] = "settings"

from django.core.management import execute_from_command_line

execute_from_command_line(sys.argv)

run() - django/core/management/commands/runserver.py

inner_run()

1. handler = self.get_handler(*args, **options)

WSGIHandler:

1) get_handler()

2) get_internal_wsgi_application() - django/core/servers/basehttp.py

from django.conf import settings

3) return WSGIHandler() - django/core/wsgi.py

2. run(self.addr, int(self.port), handler, ipv6=self.use_ipv6, threading=threading)

WSGIServer:

django/core/servers/basehttp.py

1) run(self.addr, int(self.port), handler, ipv6=self.use_ipv6, threading=threading)

httpd_cls --> 获得一个WSGIServer类型

httpd = httpd_cls(server_address, WSGIRequestHandler, ipv6=ipv6) --> WSGIServer

2) httpd.serve_forever() # while 循环接收Request请求

select model

获得 r, w, e --> read, write, error 描述符 --> [], [], []

r, w, e = [<django.core.servers.basehttp.WSGIServer object], [], []

if self in r:

self._handle_request_noblock()

self.process_request(request, client_address)

1) t = threading.Thread(target = self.process_request_thread, args = (request, client_address))

# 新建了一个线程去处理 request.

process_request_thread()

self.finish_request(request, client_address)

线程调用finish_request # call WSGIHandler:

BaseServer --> finish_request() --> self.RequestHandlerClass(request, client_address, self)

# python2.7/SocketServer.py

BaseRequestHandler --> self.handle() # python2.7/SocketServer.py

WSGIRequestHandler --> handler.run(self.server.get_app())

# self.server: WSGIServer; handler: ServerHandler; self.server.get_app(): StaticFilesHandler

BaseHandler --> self.result = application(self.environ, self.start_response)

# application: StaticFilesHandler

StaticFilesHandler(WSGIHandler) --> return self.application(environ, start_response)

# Explicitly shutdown. socket.close() merely releases the socket and waits for GC to perform the actual close.

self.shutdown_request(request)

调用 WSGIHandler(base.BaseHandler)的 __call__ 方法 - (django/core/wsgi.py)

Step 1:

1). self.load_middleware() -> Populate middleware lists from settings

2). signals.request_started.send(...) -> fires the dispatcher signal `request_started`

3). request = self.request_class(environ) -> 实例WSGIRequest(http.HttpRequest)

4). response = self.get_response(request) -> Step2

Returns an HttpResponse object for the given HttpRequest

Step 2: Request Middleware

the middleware methods applied here simply do some processing and decide whether to add, remove or supplement attributes of the request.

```python

for middleware_method in self._request_middleware:

response = middleware_method(request)

```

Step 3: 用 RegexURLResolver 处理 requested URL

生成了一个 URL resolver, 在指定的url.py里根据 regex 遍历找到对应的view.

option1: 如果是include的话, 继续找

option2: 找到了的话返回这三个东西:

1. matched item

2. a list of non-named matched groups from the URL (to be used as positional arguments for the view)

3. kwargs. eg. {'template_name': 'registration/login.html'}

`callback, callback_args, callback_kwargs = resolver_match`

这三个 View 的参数: 1. view的reference 2. args 3. kwargs

Step 4: Apply view middleware (类似Request Middleware)

for middleware_method in self._view_middleware:

response = middleware_method(request, callback, callback_args, callback_kwargs)

view的三个条件:

1) 必须可以被调用的.

2) 输入: 第一个positional参数必须为django.http.HttpRequest.

3) 输出: 返回必须为一个django.http.HttpResponse OR raise 一个异常.

Step 5: Exception Middleware

如果在view的执行中遇到异常, 就会执行_exception_middleware list 里的 所有 instance.

Step 6: Template Response

如果response有render属性的话:

1. 调用template的response middleware

2. Render response: 返回TemplateResponse,

content = template.render(context, self._request)

>>> context = Context({"my_name": "Dolores"})

>>> template.render(context)

"My name is Dolores."

Step 7: Apply response middleware, regardless of the response

Step 8:

(执行完 handler 的 get_response 方法)

对 Response 设header, cache, etc.

生成一个HttpResponse, 它的两个参数:

1. content: 一般是TemplateResponse的content (render生成的HTML代码).

2. mime_type: A value for the Content-Type header of the response. --> response_headers