Python | Flask 解决跨域问题
前言
又跨域了
使用步骤
1. 引入库
代码语言：javascript复制pip install flask-cors2. 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
代码语言：javascript复制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：
代码语言：javascript复制: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
代码语言：javascript复制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。
常用的我们可以配置 origins、methods、allow_headers、supports_credentials
所有的配置项如下：
代码语言：javascript复制: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
配置参数说明
参数 | 类型 | Head | 默认 | 说明 |
|---|---|---|---|---|
resources | 字典、迭代器或字符串 | 无 | 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-Headers | None | 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-Credentials | False | 是否允许请求发送cookie |
max_age | timedelta、整数、字符串 | Access-Control-Max-Age | None | 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
参考
- https://flask-cors.readthedocs.io/en/latest/
