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 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_origin 和 CORS 提供一些基本相同的参数。

常用的我们可以配置 origins、methods、allow_headers、supports_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

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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