CORS 策略已阻止从源“http://localhost:4200”访问“http://localhost:8080/BeginSignup”获取

Question

我正在尝试向我的 Golang AppEngine API 发送 fetch POST 请求。但是，我收到了 CORS 策略错误，我不知道为什么。这是我的代码：

这是从 Angular 调用 API 的代码

private async sendHTTPPut(data: UserInfo, func: string) {
    let requestHeaders = { 'Content-Type': 'application/json', 'Access-Control-Allow-Origin': '*' } as HeadersInit;

    console.log(requestHeaders)

    return await fetch(
        this.endpoint + func,
        {
          method: 'POST',
          headers: requestHeaders,
          body: JSON.stringify(data),
          mode: "cors"
        }
    )
  }

这是处理 CORS 的服务器代码：

func StartApp() {
    router = mux.NewRouter()

    router.HandleFunc("/", hello)
    router.HandleFunc("/hello", hello)
    router.HandleFunc("/AcceptMember", AcceptMember)
    router.HandleFunc("/CreateTeam", CreateTeam)
    router.HandleFunc("/Leave", Leave)
    router.HandleFunc("/InviteMember", InviteMember)
    router.HandleFunc("/BeginSignup", BeginSignup)
    router.HandleFunc("/ProcessSignup", ProcessSignup)
    router.HandleFunc("/CompleteSignup", CompleteSignup)
    // Scoring
    router.HandleFunc("/GetLocalScore", GetLocalScore)

    allowedOrigins := handlers.AllowedOrigins([]string { "* always" })
    allowedHeaders := handlers.AllowedHeaders([]string { "Content-Type" })

    if err := http.ListenAndServe(":8080", handlers.CORS(allowedOrigins, allowedHeaders)(router)); err != nil {
        log.Fatal(err)
    }
}

这是发送到服务器的请求：

Request URL: http://localhost:8080/BeginSignup
Referrer Policy: no-referrer-when-downgrade

Provisional headers are shown
Access-Control-Allow-Origin: *
Content-Type: application/json
Referer: http://localhost:4200/
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36 Edg/85.0.564.68

PAYLOAD
{member: {phoneNum: "0648503047"},…}
member: {phoneNum: "0648503047"}
score: null
team: {teamName: ".None", teamMembers: ["0648503047"], teamLeader: "0648503047"}

这是从服务器发回的响应：

Request URL: http://localhost:8080/BeginSignup
Request Method: OPTIONS
Status Code: 200 OK
Remote Address: [::1]:8080
Referrer Policy: no-referrer-when-downgrade
Content-Length: 0
Date: Mon, 05 Oct 2020 20:34:51 GMT
Accept: */*
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9
Access-Control-Request-Headers: access-control-allow-origin,content-type
Access-Control-Request-Method: POST
Connection: keep-alive
Host: localhost:8080
Origin: http://localhost:4200
Referer: http://localhost:4200/
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-site
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36 Edg/85.0.564.68

Answer 1

我假设您在开发模式下运行 Angular (ng serve)。 在这种情况下，CORS 错误来自角度。

您必须在 src 中添加一个包含不同端点条目的 proxy.conf.json：

{
    "/api/*": {
        "target": "http://localhost:<your-port>",
        "secure": false,
        "logLevel": "debug"
    }
}

并在你的 angular.json 中引用这个文件：

"serve": {
          "builder": "@angular-devkit/build-angular:dev-server",
          "options": {
            "browserTarget": "<your-app>:build",
            "proxyConfig": "src/proxy.conf.json"
          },
          ...
        },