javascript - 无法在 firebase 重定向结果中使用 Redux props

Question

我正在尝试在 React + Redux + Firebase 中构建 Google 身份验证。我想在谷歌身份验证后创建用户。但在 Firebase 上重定向后，this.props.createUser() 无法正常工作。

TypeError: Cannot read property 'props' of undefined

app/src/components/home.js

import React, { Component } from "react";
import { connect } from "react-redux";
import firebase from "../config/firebase";
import { createUser } from "../actions";

class Home extends Component {
  constructor(props) {
    super(props);

    this.state = {
      user: null
    };
  }

  async componentWillMount() {
    console.log("this", this.props);
    firebase.auth().onAuthStateChanged(user => {
      this.setState({ user });

      if (user) {
        this.props.history.push("/user/settings");
      }
    });

    firebase
      .auth()
      .getRedirectResult()
      .then(function(result) {
        if (result.credential) {
          var token = result.credential.accessToken;
          console.log("token", token);
        }
        var user = result.user;
        // Successfully got a user but type error in below
        this.props.createUser(user);
      })
      .catch(function(error) {
        console.log("error", error);
      });
  }

  onLogin = () => {
    const provider = new firebase.auth.GoogleAuthProvider();
    firebase.auth().signInWithRedirect(provider);
  };

  render() {
    return (
      <button className="btn btnPrimary" onClick={this.onLogin}>
        <span>Google Signin</span>
      </button>
    );
  }
}

function mapStateToProps({ user }) {
  return { user: user };
}

export default connect(mapStateToProps, { createUser })(Home);

app/src/actions/index.js

import firebase from "../config/firebase";

export function createUser(user) {
  console.log('user', user)
}

Answer 1

由于您使用 function 关键字声明回调，因此函数内的 this 指的是函数本身，而不是您在其上声明 componentWillMount 的类 方法。

最简单的解决方案是使用粗箭头表示法，就像您在其他地方所做的那样:

firebase
  .auth()
  .getRedirectResult()
  .then((result) => {
    if (result.credential) {
      var token = result.credential.accessToken;
      console.log("token", token);
    }
    var user = result.user;
    // Successfully got a user but type error in below
    this.props.createUser(user);
  })

另请参阅有关问题原因的答案以及其他解决方案:How to access the correct `this` inside a callback?