# flask实例化
def __init__(
self,
import_name, # 应用程序包的名称
static_url_path=None, # 可用于为web上的静态文件指定不同的路径。默认为“static_folder”文件夹的名称。
static_folder='static', # 包含静态文件的文件夹，这些文件应该在'static_url_path'处提供。默认为应用程序根路径中的“静态”文件夹。
static_host=None, # 添加静态路由时要使用的主机。默认为没有。当使用'host_match_true' 和配置的static_folder 时需要。
host_matching=False,# 设置“url_map.host_matching“属性。默认值为False。
subdomain_matching=False, # 在匹配路由时，考虑与:data: 'SERVER_NAME'相关的子域。默认值为False。
template_folder='templates', # 包含应用程序应该使用的模板的文件夹。默认为应用程序根路径中的“模板”文件夹。
instance_path=None, # 应用程序的可选实例路径。默认情况下，包或模块旁边的文件夹“instance”被认为是实例路径。
instance_relative_config=False, # 如果将用于加载配置的相对文件名设置为“True”，则假定它相对于实例路径，而不是相对于应用程序根目录。
root_path=None # Flask默认情况下会自动计算应用程序根目录的路径。在某些情况下，这是无法实现的(例如，如果包是Python 3命名空间包)，需要手动定义。
):
"""
The flask object implements a WSGI application and acts as the central
object. It is passed the name of the module or package of the
application. Once it is created it will act as a central registry for
the view functions, the URL rules, template configuration and much more.
The name of the package is used to resolve resources from inside the
package or the folder the module is contained in depending on if the
package parameter resolves to an actual python package (a folder with
an :file:`__init__.py` file inside) or a standard module (just a ``.py`` file).
For more information about resource loading, see :func:`open_resource`.
Usually you create a :class:`Flask` instance in your main module or
in the :file:`__init__.py` file of your package like this::
from flask import Flask
app = Flask(__name__)
.. admonition:: About the First Parameter
The idea of the first parameter is to give Flask an idea of what
belongs to your application. This name is used to find resources
on the filesystem, can be used by extensions to improve debugging
information and a lot more.
So it's important what you provide there. If you are using a single
module, `__name__` is always the correct value. If you however are
using a package, it's usually recommended to hardcode the name of
your package there.
For example if your application is defined in :file:`yourapplication/app.py`
you should create it with one of the two versions below::
app = Flask('yourapplication')
app = Flask(__name__.split('.')[0])
Why is that? The application will work even with `__name__`, thanks
to how resources are looked up. However it will make debugging more
painful. Certain extensions can make assumptions based on the
import name of your application. For example the Flask-SQLAlchemy
extension will look for the code in your application that triggered
an SQL query in debug mode. If the import name is not properly set
up, that debugging information is lost. (For example it would only
pick up SQL queries in `yourapplication.app` and not
`yourapplication.views.frontend`)
.. versionadded:: 0.7
The `static_url_path`, `static_folder`, and `template_folder`
parameters were added.
.. versionadded:: 0.8
The `instance_path` and `instance_relative_config` parameters were
added.
.. versionadded:: 0.11
The `root_path` parameter was added.
.. versionadded:: 1.0
The ``host_matching`` and ``static_host`` parameters were added.
.. versionadded:: 1.0
The ``subdomain_matching`` parameter was added. Subdomain
matching needs to be enabled manually now. Setting
:data:`SERVER_NAME` does not implicitly enable it.
:param import_name: the name of the application package
:param static_url_path: can be used to specify a different path for the
static files on the web. Defaults to the name
of the `static_folder` folder.
:param static_folder: the folder with static files that should be served
at `static_url_path`. Defaults to the ``'static'``
folder in the root path of the application.
:param static_host: the host to use when adding the static route.
Defaults to None. Required when using ``host_matching=True``
with a ``static_folder`` configured.
:param host_matching: set ``url_map.host_matching`` attribute.
Defaults to False.
:param subdomain_matching: consider the subdomain relative to
:data:`SERVER_NAME` when matching routes. Defaults to False.
:param template_folder: the folder that contains the templates that should
be used by the application. Defaults to
``'templates'`` folder in the root path of the
application.
:param instance_path: An alternative instance path for the application.
By default the folder ``'instance'`` next to the
package or module is assumed to be the instance
path.
:param instance_relative_config: if set to ``True`` relative filenames
for loading the config are assumed to
be relative to the instance path instead
of the application root.
:param root_path: Flask by default will automatically calculate the path
to the root of the application. In certain situations
this cannot be achieved (for instance if the package
is a Python 3 namespace package) and needs to be
manually defined.
"""
# 路由
def route(self, rule, **options):
"""A decorator that is used to register a view function for a
given URL rule. This does the same thing as :meth:`add_url_rule`
but is intended for decorator usage::
@app.route('/')
def index():
return 'Hello World'
For more information refer to :ref:`url-route-registrations`.
:param rule: the URL rule as string
:param endpoint: the endpoint for the registered URL rule. Flask
itself assumes the name of the view function as
endpoint
:param options: the options to be forwarded to the underlying
:class:`~werkzeug.routing.Rule` object. A change
to Werkzeug is handling of method options. methods
is a list of methods this rule should be limited
to (``GET``, ``POST`` etc.). By default a rule
just listens for ``GET`` (and implicitly ``HEAD``).
Starting with Flask 0.6, ``OPTIONS`` is implicitly
added and handled by the standard request handling.
"""
def decorator(f):
endpoint = options.pop('endpoint', None)
self.add_url_rule(rule, endpoint, f, **options)
return f
return decorator
# 执行run
def run(self, host=None, port=None, debug=None,
load_dotenv=True, **options):
"""Runs the application on a local development server.
Do not use ``run()`` in a production setting. It is not intended to
meet security and performance requirements for a production server.
Instead, see :ref:`deployment` for WSGI server recommendations.
If the :attr:`debug` flag is set the server will automatically reload
for code changes and show a debugger in case an exception happened.
If you want to run the application in debug mode, but disable the
code execution on the interactive debugger, you can pass
``use_evalex=False`` as parameter. This will keep the debugger's
traceback screen active, but disable code execution.
It is not recommended to use this function for development with
automatic reloading as this is badly supported. Instead you should
be using the :command:`flask` command line script's ``run`` support.
.. admonition:: Keep in Mind
Flask will suppress any server error with a generic error page
unless it is in debug mode. As such to enable just the
interactive debugger without the code reloading, you have to
invoke :meth:`run` with ``debug=True`` and ``use_reloader=False``.
Setting ``use_debugger`` to ``True`` without being in debug mode
won't catch any exceptions because there won't be any to
catch.
:param host: the hostname to listen on. Set this to ``'0.0.0.0'`` to
have the server available externally as well. Defaults to
``'127.0.0.1'`` or the host in the ``SERVER_NAME`` config variable
if present.
:param port: the port of the webserver. Defaults to ``5000`` or the
port defined in the ``SERVER_NAME`` config variable if present.
:param debug: if given, enable or disable debug mode. See
:attr:`debug`.
:param load_dotenv: Load the nearest :file:`.env` and :file:`.flaskenv`
files to set environment variables. Will also change the working
directory to the directory containing the first file found.
:param options: the options to be forwarded to the underlying Werkzeug
server. See :func:`werkzeug.serving.run_simple` for more
information.
.. versionchanged:: 1.0
If installed, python-dotenv will be used to load environment
variables from :file:`.env` and :file:`.flaskenv` files.
If set, the :envvar:`FLASK_ENV` and :envvar:`FLASK_DEBUG`
environment variables will override :attr:`env` and
:attr:`debug`.
Threaded mode is enabled by default.
.. versionchanged:: 0.10
The default port is now picked from the ``SERVER_NAME``
variable.
"""
@app.route('/user/<username>')
def show_user_profile(username):
# show the user profile for that user
return 'User %s' % username
@app.route('/post/<int:post_id>')
def show_post(post_id):
# show the post with the given id, the id is an integer
return 'Post %d' % post_id
所以，这对你来说意味着什么？除非你要做类似单元测试的东西，否则你基本上可以完全无视它。你会发现依赖于一段请求对象的代码，因没有请求对象无法正常运行。解决方案是，自行创建一个请求对象并且把它绑定到环境中。单元测试的最简单的解决方案是：用test_request_context() 环境管理器。结合 with 声明，绑定一个测试请求，这样你才能与之交互。
from flask import request
with app.test_request_context('/hello', method='POST'):
# now you can do something with the request until the
# end of the with block, such as basic assertions:
assert request.path == '/hello'
assert request.method == 'POST'
'''
另一种可能是：传递整个 WSGI 环境给 request_context() 方法
'''
from flask import request
with app.request_context(environ):
assert request.method == 'POST'
8-2 Request对象
当前请求的 HTTP 方法可通过 method 属性来访问。
通过:attr:~flask.request.form 属性来访问表单数据（ POST 或 PUT 请求提交的数据）。
from flask import request
@app.route('/login', methods=['POST', 'GET'])
def login():
error = None
if request.method == 'POST':
if valid_login(request.form['username'],
request.form['password']):
return log_the_user_in(request.form['username'])
else:
error = 'Invalid username/password'
# the code below is executed if the request method
# was GET or the credentials were invalid
return render_template('login.html', error=error)
注意：当访问 form 属性中的不存在的键会发生什么？会抛出一个特殊的KeyError异常。
你可以像捕获标准的KeyError一样来捕获它。 如果你不这么做，它会显示一个 HTTP 400 Bad Request 错误页面。所以，多数情况下你并不需要干预这个行为。
8-2-1 args属性 - 访问URL提交的参数（/…?key=value）
searchword = request.args.get('q', '')
注意！！推荐用 get 来访问 URL 参数或捕获 KeyError ，因为用户可能会修改 URL，向他们展现一个 400 bad request 页面会影响用户体验。
九、文件上传
确保在 HTML 表单中设置enctype="multipart/form-data" 属性，不然你的浏览器根本不会发送文件。
from flask import request
from werkzeug import secure_filename
@app.route('/upload', methods=['GET', 'POST'])
def upload_file():
if request.method == 'POST':
f = request.files['the_file']
f.save('/var/www/uploads/' + secure_filename(f.filename))
...
十、Cookies
cookies - 访问Cookies
请求对象的cookies 属性是一个内容为客户端提交的所有 Cookies 的字典。如果你想使用会话，请不要直接使用 Cookies
获取 cookies.get(' cookies’s name ')
from flask import request
@app.route('/')
def index():
username = request.cookies.get('username')
# use cookies.get(key) instead of cookies[key] to not get a
# KeyError if the cookie is missing.
set_cookies - 设置Cookies
from flask import make_response
@app.route('/')
def index():
resp = make_response(render_template(...))
resp.set_cookie('username', 'the username')
return resp
