Flask 解决跨域问题

使用步骤

引入库

pip install flask-cors

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, 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

2.使用 @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}!'

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

参考

https://flask-cors.readthedocs.io/en/latest/