python video tutorialcolumn introduces Python Flask to solve cross-domain problems.

Directory of series of articles

Table of Contents

• Directory of series of articles
• Preface
• Usage steps
  • 1. Import the library
  • 2. Configuration
    • 1. Use theCORS functionto configure global routing
    • 2. Use@cross_originto configure single-line routing
  • Configuration parameter description
##Summary
• Reference

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Preface

Holy crap, it’s cross-domain again

Usage steps

1. Import the library

pip install flask-cors复制代码

2. Configuration

flask-cors has two usages, one is for global use, and the other is for specified routing

1. Use the

CORS functionConfigure global routing

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

CORSprovides some parameters to help us customize the operation.

We can configure commonly used

origins,methods,allow_headers,supports_credentials

All configuration items are as follows:

: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. Use

@cross_originto configure single-line routing

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

where

cross_originandCORSprovides some essentially the same parameters.

We can configure commonly used

origins,methods,allow_headers,supports_credentials

All configuration items are as follows:

: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

Configuration parameter description

##Parameter resources origins methods expose_headers allow_headers ##supports_credentials Boolean value Access-Control- Allow-Credentials False Whether to allow requests to send cookies timedelta, integer, string In the cross-domain configuration of flask, we can use flask-cors

Type	Head	Default	Description
Dictionary, iterator or string	None	All	Configure routing interfaces that allow cross-domain routing
List, string or regular expression	Access-Control-Allow-Origin	*	Configure origins that allow cross-domain access
List, string	Access-Control-Allow-Methods	[GET, HEAD, POST, OPTIONS, PUT, PATCH, DELETE]	Configure cross-domain support Request method
List, string	Access-Control-Expose-Headers	None	Customize request response Head information
List, string or regular expression	Access-Control-Request-Headers	*	Configure cross-domain request headers
				##max_age
Access-Control-Max-Age	None	Valid duration of preflight request		##Summary

for configuration, where

CORS function

is used for global configuration, and

@cross_originis used to implement Configuration of specific routes.More related free learning recommendations:

python video tutorial

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