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    Python Flask大刀解决跨域问题

    coldplay.xixicoldplay.xixi2020-10-14 17:39:01转载325

    python视频教程栏目为大家介绍Python Flask解决跨域问题。

    系列文章目录

    Table of Contents


    前言

    我靠,又跨域了

    使用步骤

    1. 引入库

    pip install flask-cors复制代码

    2. 配置

    flask-cors 有两种用法,一种为全局使用,一种对指定的路由使用

    1. 使用 CORS函数 配置全局路由

    from flask import Flask, requestfrom flask_cors import CORS
    
    app = Flask(__name__)
    CORS(app, supports_credentials=True)复制代码

    其中 CORS 提供了一些参数帮助我们定制一下操作。

    常用的我们可以配置 originsmethodsallow_headerssupports_credentials

    所有的配置项如下:

    :param resources:
        The series of regular expression and (optionally) associated CORS
        options to be applied to the given resource path.
    
        If the argument is a dictionary, it's keys must be regular expressions,
        and the values must be a dictionary of kwargs, identical to the kwargs
        of this function.
    
        If the argument is a list, it is expected to be a list of regular
        expressions, for which the app-wide configured options are applied.
    
        If the argument is a string, it is expected to be a regular expression
        for which the app-wide configured options are applied.
    
        Default : Match all and apply app-level configuration
    
    :type resources: dict, iterable or string
    
    :param origins:
        The origin, or list of origins to allow requests from.
        The origin(s) may be regular expressions, case-sensitive strings,
        or else an asterisk
    
        Default : '*'
    :type origins: list, string or regex
    
    :param methods:
        The method or list of methods which the allowed origins are allowed to
        access for non-simple requests.
    
        Default : [GET, HEAD, POST, OPTIONS, PUT, PATCH, DELETE]
    :type methods: list or string
    
    :param expose_headers:
        The header or list which are safe to expose to the API of a CORS API
        specification.
    
        Default : None
    :type expose_headers: list or string
    
    :param allow_headers:
        The header or list of header field names which can be used when this
        resource is accessed by allowed origins. The header(s) may be regular
        expressions, case-sensitive strings, or else an asterisk.
    
        Default : '*', allow all headers
    :type allow_headers: list, string or regex
    
    :param supports_credentials:
        Allows users to make authenticated requests. If true, injects the
        `Access-Control-Allow-Credentials` header in responses. This allows
        cookies and credentials to be submitted across domains.
    
        :note: This option cannot be used in conjuction with a '*' origin
    
        Default : False
    :type supports_credentials: bool
    
    :param max_age:
        The maximum time for which this CORS request maybe cached. This value
        is set as the `Access-Control-Max-Age` header.
    
        Default : None
    :type max_age: timedelta, integer, string or None
    
    :param send_wildcard: If True, and the origins parameter is `*`, a wildcard
        `Access-Control-Allow-Origin` header is sent, rather than the
        request's `Origin` header.
    
        Default : False
    :type send_wildcard: bool
    
    :param vary_header:
        If True, the header Vary: Origin will be returned as per the W3
        implementation guidelines.
    
        Setting this header when the `Access-Control-Allow-Origin` is
        dynamically generated (e.g. when there is more than one allowed
        origin, and an Origin than '*' is returned) informs CDNs and other
        caches that the CORS headers are dynamic, and cannot be cached.
    
        If False, the Vary header will never be injected or altered.
    
        Default : True
    :type vary_header: bool复制代码

    2. 使用 @cross_origin 来配置单行路由

    from flask import Flask, requestfrom flask_cors import cross_origin
    
    app = Flask(__name__)@app.route('/')@cross_origin(supports_credentials=True)def hello():
        name = request.args.get("name", "World")    return f'Hello, {name}!'复制代码

    其中 cross_originCORS 提供一些基本相同的参数。

    常用的我们可以配置 originsmethodsallow_headerssupports_credentials

    所有的配置项如下:

    :param origins:
        The origin, or list of origins to allow requests from.
        The origin(s) may be regular expressions, case-sensitive strings,
        or else an asterisk
    
        Default : '*'
    :type origins: list, string or regex
    
    :param methods:
        The method or list of methods which the allowed origins are allowed to
        access for non-simple requests.
    
        Default : [GET, HEAD, POST, OPTIONS, PUT, PATCH, DELETE]
    :type methods: list or string
    
    :param expose_headers:
        The header or list which are safe to expose to the API of a CORS API
        specification.
    
        Default : None
    :type expose_headers: list or string
    
    :param allow_headers:
        The header or list of header field names which can be used when this
        resource is accessed by allowed origins. The header(s) may be regular
        expressions, case-sensitive strings, or else an asterisk.
    
        Default : '*', allow all headers
    :type allow_headers: list, string or regex
    
    :param supports_credentials:
        Allows users to make authenticated requests. If true, injects the
        `Access-Control-Allow-Credentials` header in responses. This allows
        cookies and credentials to be submitted across domains.
    
        :note: This option cannot be used in conjuction with a '*' origin
    
        Default : False
    :type supports_credentials: bool
    
    :param max_age:
        The maximum time for which this CORS request maybe cached. This value
        is set as the `Access-Control-Max-Age` header.
    
        Default : None
    :type max_age: timedelta, integer, string or None
    
    :param send_wildcard: If True, and the origins parameter is `*`, a wildcard
        `Access-Control-Allow-Origin` header is sent, rather than the
        request's `Origin` header.
    
        Default : False
    :type send_wildcard: bool
    
    :param vary_header:
        If True, the header Vary: Origin will be returned as per the W3
        implementation guidelines.
    
        Setting this header when the `Access-Control-Allow-Origin` is
        dynamically generated (e.g. when there is more than one allowed
        origin, and an Origin than '*' is returned) informs CDNs and other
        caches that the CORS headers are dynamic, and cannot be cached.
    
        If False, the Vary header will never be injected or altered.
    
        Default : True
    :type vary_header: bool
    
    :param automatic_options:
        Only applies to the `cross_origin` decorator. If True, Flask-CORS will
        override Flask's default OPTIONS handling to return CORS headers for
        OPTIONS requests.
    
        Default : True
    :type automatic_options: bool复制代码

    配置参数说明

    参数类型Head默认说明
    resources字典、迭代器或字符串全部配置允许跨域的路由接口
    origins列表、字符串或正则表达式Access-Control-Allow-Origin*配置允许跨域访问的源
    methods列表、字符串Access-Control-Allow-Methods[GET, HEAD, POST, OPTIONS, PUT, PATCH, DELETE]配置跨域支持的请求方式
    expose_headers列表、字符串Access-Control-Expose-HeadersNone自定义请求响应的Head信息
    allow_headers列表、字符串或正则表达式Access-Control-Request-Headers*配置允许跨域的请求头
    supports_credentials布尔值Access-Control-Allow-CredentialsFalse是否允许请求发送cookie
    max_agetimedelta、整数、字符串Access-Control-Max-AgeNone预检请求的有效时长

    总结

    在 flask 的跨域配置中,我们可以使用 flask-cors 来进行配置,其中 CORS 函数 用来做全局的配置, @cross_origin 来实现特定路由的配置。

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