来自 React 的 Flask API 调用的 CORS 问题都在 localhost

Question

我正在从 React 调用 Flask API（都在 localhost 上运行）并且遇到了 CORS 问题。 发出请求时，浏览器（Chrome）给出以下错误

Access to XMLHttpRequest at 'http://localhost:5000/sas' from origin 'http://localhost:3000' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: Redirect is not allowed for a preflight request.

设置

Flask 设置如下

from flask_cors import CORS
from flask import Flask, request, Response
from flask_restful import Api, Resource
import json

class SAS(Resource):
    def get(self):
        content = request.json
        js = json.dumps(
            {
                "Response": "Some response"
            }
        )
        resp = Response(js, status=200, mimetype='application/json')
        return resp

app = Flask(__name__)
cors = CORS(app)
api = Api(app)
api.add_resource(SAS, '/sas/')

React中使用axios的调用如下

  buttonPressed = async event => {
    event.preventDefault();
    const response = await axios.get(`http://localhost:5000/sas`, {
      data: {
        user: "user",
        file_name: "user",
        directory_name: "user"
      }
    });
  };

注意：从 Postman 运行请求可以正常工作并显示标头 Access-Control-Allow-Origin = *

知道如何解决这个问题吗？

另外，如果我将 React 前端和 API 作为 dockerized 应用程序运行，我应该不会再看到这个问题了，对吗？在这种情况下，我也会考虑在开发过程中绕过问题

Answer 1

请尝试使用 cross_origin 装饰器，就像在这个最小示例中一样：

from flask import Flask, request, jsonify
from flask_cors import CORS, cross_origin
app = Flask(__name__)
CORS(app, support_credentials=True)

@app.route('/sas', methods=['POST', 'GET', 'OPTIONS'])
@cross_origin(supports_credentials=True)
def index():
    if(request.method=='POST'):
     some_json = request.get_json()
     return jsonify({"key": some_json})
    else:
        return jsonify({"GET": "Nice Get Request"})

if __name__=="__main__":
    app.run(host='0.0.0.0', port=5000)

如果可行，那么我们将在您的代码中实现相同的装饰器。