预检未通过控制检查访问控制允许来源不存在

Question

我在 React 中有一个简单的客户端运行。我正在尝试使用 Axios 向我在本地运行的 Go 服务器发出 GET 请求。 React 代码在端口 3000 上运行，Go 服务器在 4000 上。

如果我将 GET 请求本身粘贴到浏览器中 window 它工作正常：http://localhost:4000/numberconverter?number=10&oldBase=10&newBase=2

我做了一些研究并找到了，但是插件和 Chrome 选项没有帮助。这不是我做过的唯一研究，但似乎是最有希望的。我发现的大部分内容都不涉及 Go 服务器。

我也找到了this post，但是那也没有解决我的问题。如果我取消注释服务器中的代码，它仍然会失败。

如果我将允许的方法更改为：

writer.Header().Set("Access-Control-Allow-Methods", "GET, POST, PATCH, PUT, DELETE, OPTIONS")

失败并出现 405 错误。服务器打印出来：

&{0xc4200f4000 0xc42000a500 {} 0x10ec430 true false false false 0xc4200143c0 {0xc420100000 map[Access-Control-Allow-Origin:[*] Access-Control-Allow-Methods:[GET, POST, PATCH, PUT, DELETE, OPTIONS] Content-Type:[text/plain; charset=utf-8] X-Content-Type-Options:[nosniff]] false false} map[Access-Control-Allow-Origin:[*] Access-Control-Allow-Methods:[GET, POST, PATCH, PUT, DELETE, OPTIONS] Content-Type:[text/plain; charset=utf-8] X-Content-Type-Options:[nosniff]] true 19 -1 405 false false [] 0 [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0] 0xc4200620e0 0}

我想我的问题是这是服务器端还是客户端的问题以及我该如何解决这个问题？

客户：

import React, {Component} from 'react';
import axios from 'axios';

class Converter extends Component {
    constructor(props) {
        super(props);
        this.state = {
            // number: 0,
            // base: 10,
            // newBase: 10
        };
        this.convertButtonPressed = this.convertButtonPressed.bind(this);
        this.handleChange = this.handleChange.bind(this);
    }

    handleChange(event) {
        const target = event.target;
        const value = target.value;
        const name = target.name;

        this.setState({
        [name]: value
        });
    }

    convertButtonPressed(event) {
        axios({
            method: 'GET',
            baseURL: 'http://localhost:4000/',
            url: '/numberconverter',
            headers: {
                'Access-Control-Allow-Origin': '*',
                'Access-Control-Allow-Methods': 'GET, POST, PATCH, PUT, DELETE, OPTIONS',
                'Access-Control-Allow-Headers': 'Origin, Content-Type, X-Auth-Token'
            },
            params: {
            number: this.state.number,
            oldBase: this.state.base,
            newBase: this.state.newBase
            }
        });
    }

    render() {
        return (
        <div className="App">
            <p>Number Converter</p>
            <div>
            Number:
            <input name="number" onChange={this.handleChange} type="text" placeholder="Number"></input><br />
            Base:
            <input name="base" onChange={this.handleChange} type="text" placeholder="Base"></input><br />
            New Base:
            <input name="newBase" onChange={this.handleChange} type="text" placeholder="New Base"></input><br />
            </div>
            <button onClick={this.convertButtonPressed}>Convert</button>
        </div>
        );
    }
}

export default Converter;

服务器：

package rest

// Example:
// http://localhost:3000/numberconverter?number=500000&oldBase=10&newBase=16

import (
    "fmt"
    "log"
    "net/http"

    "../converter"
)

// Start starts the server
func Start() {
    //muxRouter := http.NewServeMux()
    //muxRouter.HandleFunc("/numberconverter", numberconverter)
    //http.Handle("/", muxRouter)
    http.HandleFunc("/numberconverter", numberconverter)
    log.Fatal(http.ListenAndServe(":4000", nil))
}

func numberconverter(writer http.ResponseWriter, response *http.Request) {
    //writer.Header().Set("Access-Control-Allow-Origin", "*")
    //writer.Header().Set("Access-Control-Allow-Methods", "*")
    //writer.Header().Set("Content-Type", "text/html; charset=utf-8")

    // Check if the method is a get
    if response.Method != http.MethodGet {
        http.Error(writer, http.StatusText(405), 405)
        fmt.Println(writer)
        return
    }

    number := response.FormValue("number")
    oldBase := response.FormValue("oldBase")
    newBase := response.FormValue("newBase")
    result := converter.ConvertStringNumberToNewBase(number, oldBase, newBase)
    fmt.Fprintf(writer, "%s base %s is %s in base %s", number, oldBase, result, newBase)
}

Answer 1

一旦我在 React 代码中注释掉 headers，GET 请求就起作用了。感谢 sideshowbarker 的回答。非常感谢。

convertButtonPressed(event) {
    axios({
        method: 'GET',
        baseURL: 'http://localhost:4000/',
        url: '/numberconverter',
        // headers: {
        //     'Access-Control-Allow-Origin': '*',
        //     'Access-Control-Allow-Methods': 'GET, POST, PATCH, PUT, DELETE, OPTIONS',
        //     'Access-Control-Allow-Headers': 'Origin, Content-Type, X-Auth-Token'
        // },
        params: {
          number: this.state.number,
          oldBase: this.state.base,
          newBase: this.state.newBase
        }
      });
}

预检未通过控制检查访问控制允许来源不存在

Preflight Doesn't Pass Control Check Access-Control-Allow-Origin Not Present

rest

go

cors

preflight

reactjs