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关于python:Python-Flask-解决跨域问题

jiezi

系列文章目录

前言

我靠，又跨域了

应用步骤

1. 引入库 

pip install flask-cors

2. 配置

flask-cors 有两种用法，一种为全局应用，一种对指定的路由应用

1. 应用 CORS 函数 配置全局路由 

from flask import Flask, request
from flask_cors import CORS

app = Flask(__name__)
CORS(app, supports_credentials=True)

其中 CORS 提供了一些参数帮忙咱们定制一下操作。

罕用的咱们能够配置 origins、methods、allow_headers、supports_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
    """

2. 应用 @cross_origin 来配置单行路由 

from flask import Flask, request
from 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}!'

其中 cross_origin 和 CORS 提供一些基本相同的参数。

罕用的咱们能够配置 origins、methods、allow_headers、supports_credentials

所有的配置项如下：

"""
    This function is the decorator which is used to wrap a Flask route with.
    In the simplest case, simply use the default parameters to allow all
    origins in what is the most permissive configuration. If this method
    modifies state or performs authentication which may be brute-forced, you
    should add some degree of protection, such as Cross Site Forgery
    Request protection.

    :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

配置参数阐明

参数 类型 Head 默认 阐明
resources 字典、迭代器或字符串 无 全副 配置容许跨域的路由接口
origins 列表、字符串或正则表达式 Access-Control-Allow-Origin * 配置容许跨域拜访的源
methods 列表、字符串 Access-Control-Allow-Methods [GET, HEAD, POST, OPTIONS, PUT, PATCH, DELETE] 配置跨域反对的申请形式
expose_headers 列表、字符串 Access-Control-Expose-Headers None 自定义申请响应的 Head 信息
allow_headers 列表、字符串或正则表达式 Access-Control-Request-Headers * 配置容许跨域的申请头
supports_credentials 布尔值 Access-Control-Allow-Credentials False 是否容许申请发送 cookie
max_age timedelta、整数、字符串 Access-Control-Max-Age None 预检申请的无效时长

总结

在 flask 的跨域配置中，咱们能够应用 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

参考

  • https://flask-cors.readthedoc…

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