ReactJS/Express Axios POST 返回 404，来自 Postman

我不知道我在这里做错了什么。 POST 方法适用于 Postman，但不适用于 React 前端。

users.js (/api/users/login)

// @route   POST api/users/login
// @desc    Login user / Returning JWT Token
// @access  Public
router.post('/login', (req, res, next) => {
  const { errors, isValid } = validateLoginInput(req.body);

  // Check validation
  if (!isValid) {
    return res.status(400).json(errors);
  }

  const email = req.body.email;
  const password = req.body.password;

  // Find user by email
  User.findOne({ email }) // matching email: email
    .then(user => {
      if (!user) {
        errors.email = 'User not found';
        return res.status(404).json(errors);
      }

    // Check Password
    bcrypt.compare(password, user.password)
      .then(isMatch => {
        if(isMatch) {

          // User matched. Create JWT payload
          const payload = {
            id: user.id
          } 

          // Sign Token
          jwt.sign(
            payload,
            keys.secretOrKey, 
            { expiresIn: 3600 }, 
            (err, token) => {
              res.json({
                success: true,
                token: 'Bearer ' + token
              });
          });
        } else {
          errors.password = 'Password incorrect'
          return res.status(400).json(errors);
        }
    });
  }); 
});

登录用户()函数：

export const loginUser = userData => dispatch => {
  axios
    .post("/api/users/login", userData)
    .then(res => {
      // Save to localStorage
      const { token } = res.data;
      // Set token to localStorage
      localStorage.setItem("jwtToken", token); // only stores strings
      // Set token to Auth header
      setAuthToken(token);
      // Decode token to get user data
      const decoded = jwt_decode(token);
      // Set current user
      dispatch(setCurrentUser(decoded));
    })
    .catch(err =>
      dispatch({
        type: GET_ERRORS,
        payload: err.response.data
      })
    );
};

React 组件中的 onSubmit() 函数：

  onSubmit(e) {
    e.preventDefault();

    const userData = {
      email: this.state.email,
      password: this.state.password
    }

    this.props.loginUser(userData);
  }

Network:

Request URL: http://localhost:3000/api/users/login
Request Method: POST
Status Code: 404 Not Found
Remote Address: 127.0.0.1:3000
Referrer Policy: no-referrer-when-downgrade
Connection: keep-alive
Content-Length: 155
Content-Security-Policy: default-src 'self'
Content-Type: text/html; charset=utf-8
Date: Mon, 16 Jul 2018 01:53:03 GMT
Vary: Accept-Encoding
X-Content-Type-Options: nosniff
X-Powered-By: Express
Accept: application/json, text/plain, */*
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9
Connection: keep-alive
Content-Length: 46
Content-Type: application/json;charset=UTF-8
Cookie: io=VtWk-hb742jVakwrAAAE; PHPSESSID=ige5g7257th8hiksjomg2khouu; i18next=en; connect.sid=s%3Aq6FkEveJbDYoKTy386QESFBxGaW8MjKd.qSBAkm2t23Ww4ZtHtcs7%2F1e5tDn528i0C6Hv7U3PwI0
Host: localhost:3000
Origin: http://localhost:3000
Referer: http://localhost:3000/login
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36
{email: "[email protected] /cdn-cgi/l/email-protection", password: "admin"}
email
:
"[email protected] /cdn-cgi/l/email-protection"
password
:
"admin"

server.js 上的端口：

// Initializint the port
const port = process.env.PORT || 5000;

app.listen(port, () => console.log(`Server running on port ${port}`));

我在这里检查了一些类似的问题，其中大部分与标题有关。就我而言，标头是 application/json，所以我认为问题不存在。通过 Postman 到达端点没有问题。

您的反应应用程序与后端应用程序运行在不同的端口上。create-react-app在端口 3000 上运行，正如您所说，您的后端在端口 5000 上运行。

当您的客户端应用程序向服务器发出请求时，它实际上向端口 3000 发出请求，如您在此处看到的。

请求网址：http://localhost:3000/api/users/login http://localhost:3000/api/users/login

这样做是因为您从未在请求​​中指定原始 url，如您在此处看到的post("/api/users/login", userData)，在这种情况下，它默认为请求来自的同一端口，即端口 3000，而端口 3000 实际上没有您请求的 url。

您可以通过在请求中包含原始 url 或向 React 应用程序 package.json 添加代理来解决此问题，如下所示。

https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md#proxying-api-requests-in-development https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md#proxying-api-requests-in-development