Flask之 urls & views

两种写法

from flask import Flask
app = Flask(__name__)


# 方法1：
# @app.route('/index')
def index():
    return 'index'


# 方法2：
app.add_url_rule('/index', view_func=index)


if __name__ == '__main__':
    app.run()

源码分析：

def route(self, rule, **options):
    def decorator(f):
        endpoint = options.pop('endpoint', None)
        self.add_url_rule(rule, endpoint, f, **options)
        return f
    return decorator
    

# 第一步
app.route = app.decorator


# 第二步
route('/index') = decorator('/index')


# 第三步
app.add_url_rule('/index', endpoint=None, func)

---

endpoints 重名报错

源码：

def add_url_rule(self, rule, endpoint=None, view_func=None,
             provide_automatic_options=None, **options):
        
    if endpoint is None:
        # endpoint默认为函数名
        endpoint = _endpoint_from_view_func(view_func)
        
        ###################################################################
        # 被调用函数
        def _endpoint_from_view_func(view_func):
            """Internal helper that returns the default endpoint for a given
            function.  This always is the function name.
            """
            assert view_func is not None, 'expected view func if endpoint ' \
                                          'is not provided.'
            return view_func.__name__
        ####################################################################
        
    options['endpoint'] = endpoint
    
    if view_func is not None:
        # 获取已存在的endpoint对应的func
        old_func = self.view_functions.get(endpoint)
        
        # 若endpoint对应的函数存在且不等于新的函数那么直接报错
        if old_func is not None and old_func != view_func:
            raise AssertionError('View function mapping is overwriting an '
                                 'existing endpoint function: %s' % endpoint)

---

route参数

@app.route和app.add_url_rule参数：
    rule  
        # URL规则
    
    view_func
        # 视图函数名称
    
    defaults=None
        # 默认值,当URL中无参数，函数需要参数时，使用defaults={'k':'v'}为函数提供参数
    
    endpoint=None
        # 名称，用于反向生成URL，即： url_for('名称')
    
    methods=None
        # 允许的请求方式，如：["GET","POST"]
    
    strict_slashes=None
        # 对URL最后的 / 符号是否严格要求，如：
        @app.route('/index',strict_slashes=False)，
            访问 http://www.xx.com/index/ 或 http://www.xx.com/index均可
        @app.route('/index',strict_slashes=True)
            仅访问 http://www.xx.com/index 


    redirect_to=None,           
        # 重定向到指定地址,如：
        @app.route('/index/<int:nid>', redirect_to='/home/<nid>')
        或
        def func(adapter, nid):
            return "/home/888"
        @app.route('/index/<int:nid>', redirect_to=func)
   
   
    subdomain=None,             
        # 子域名访问
        from flask import Flask, views, url_for

        app = Flask(import_name=__name__)
        app.config['SERVER_NAME'] = 'wupeiqi.com:5000'


        @app.route("/", subdomain="admin")
        def static_index():
            """Flask supports static subdomains
            This is available at static.your-domain.tld"""
            return "static.your-domain.tld"


        @app.route("/dynamic", subdomain="<username>")
        def username_index(username):
            """Dynamic subdomains are also supported
            Try going to user1.your-domain.tld/dynamic"""
            return username + ".your-domain.tld"


        if __name__ == '__main__':
            app.run()

---

CBV

from flask import Flask, views

app = Flask(__name__)

def wrapper(func):
    def inner(*args, **kwargs):
        return func(*args, **kwargs)
    return inner


class UserView(views.MethodView):
    # methods = ['GET']
    decorators = [wrapper,]  # 可以添加装饰器函数，调用get和post方法时会自动调用

    def get(self, *args, **kwargs):
        return 'GET'

    def post(self, *args, **kwargs):
        return 'POST'


app.add_url_rule('/user',None,UserView.as_view('user_list'))


if __name__ == '__main__':
    app.run()

---

自定义正则

@app.route('/user/<username>')
@app.route('/post/<int:post_id>')
@app.route('/post/<float:post_id>')
@app.route('/post/<path:path>')
@app.route('/login', methods=['GET', 'POST'])

常用路由系统有以上五种，所有的路由系统都是基于一下对应关系来处理：

DEFAULT_CONVERTERS = {
    'default':          UnicodeConverter,
    'string':           UnicodeConverter,
    'any':              AnyConverter,
    'path':             PathConverter,
    'int':              IntegerConverter,
    'float':            FloatConverter,
    'uuid':             UUIDConverter,
}

from flask import Flask, views, url_for
from werkzeug.routing import BaseConverter

app = Flask(import_name=__name__)


class RegexConverter(BaseConverter):
    """
    自定义URL匹配正则表达式
    """
    def __init__(self, map, regex):
        super(RegexConverter, self).__init__(map)
        self.regex = regex

    def to_python(self, value):
        """
        路由匹配时，匹配成功后传递给视图函数中参数的值
        :param value: 
        :return: 
        """
        return int(value)

    def to_url(self, value):
        """
        使用url_for反向生成URL时，传递的参数经过该方法处理，返回的值用于生成URL中的参数
        :param value: 
        :return: 
        """
        val = super(RegexConverter, self).to_url(value)
        return val


# 添加到flask中
app.url_map.converters['regex'] = RegexConverter


@app.route('/index/<regex("\d+"):nid>')
def index(nid):
    print(url_for('index', nid='888'))
    return 'Index'


if __name__ == '__main__':
    app.run()